gpiozero¶

A simple interface to GPIO devices with Raspberry Pi, developed and maintained by Ben Nuttall and Dave Jones.

About¶

Component interfaces are provided to allow a frictionless way to get started with physical computing:

from gpiozero import LED
from time import sleep

led = LED(17)

while True:
    led.on()
    sleep(1)
    led.off()
    sleep(1)

With very little code, you can quickly get going connecting your components together:

from gpiozero import LED, Button
from signal import pause

led = LED(17)
button = Button(3)

button.when_pressed = led.on
button.when_released = led.off

pause()

You can advance to using the declarative paradigm along with provided to describe the behaviour of devices and their interactions:

from gpiozero import OutputDevice, MotionSensor, LightSensor
from gpiozero.tools import booleanized, all_values
from signal import pause

garden = OutputDevice(17)
motion = MotionSensor(4)
light = LightSensor(5)

garden.source = all_values(booleanized(light, 0, 0.1), motion)

pause()

See the chapter on Source/Values for more information.

The library includes interfaces to many simple everyday components, as well as some more complex things like sensors, analogue-to-digital converters, full colour LEDs, robotics kits and more. See the Recipes chapter of the documentation for ideas on how to get started.

Pin factories¶

GPIO Zero builds on a number of underlying pin libraries, including RPi.GPIO and pigpio, each with their own benefits. You can select a particular pin library to be used, either for the whole script or per-device, according to your needs. See the section on changing the pin factory.

A “mock pin” interface is also provided for testing purposes. Read more about this in the section on mock pins.

Installation¶

GPIO Zero is installed by default in the Raspberry Pi OS desktop image, available from raspberrypi.org. To install on Raspberry Pi OS Lite or other operating systems, including for PCs using remote GPIO, see the Installing chapter.

Documentation¶

Comprehensive documentation is available at https://gpiozero.readthedocs.io/. Please refer to the Contributing and Development chapters in the documentation for information on contributing to the project.

Issues and questions¶

If you have a feature request or bug report, please open an issue on GitHub. If you have a question or need help, this may be better suited to our GitHub discussion board, the Raspberry Pi Stack Exchange or the Raspberry Pi Forums.

Python 2 support¶

Warning

Version 1.6.0 of GPIO Zero is the last to support Python 2. The next release will be Version 2.0.0 and will support Python 3 only.

Contributors¶

See the contributors page on GitHub for more info.

Table of Contents¶

Installing GPIO Zero¶

GPIO Zero is installed by default in the Raspberry Pi OS desktop image, and the Raspberry Pi Desktop image for PC/Mac, both available from raspberrypi.org. Follow these guides to installing on Raspberry Pi OS Lite and other operating systems, including for PCs using the remote GPIO feature.

Raspberry Pi¶

GPIO Zero is packaged in the apt repositories of Raspberry Pi OS, Debian and Ubuntu. It is also available on PyPI.

apt¶

First, update your repositories list:

pi@raspberrypi:~$ sudo apt update

Then install the package for Python 3:

pi@raspberrypi:~$ sudo apt install python3-gpiozero

or Python 2:

pi@raspberrypi:~$ sudo apt install python-gpiozero

pip¶

If you’re using another operating system on your Raspberry Pi, you may need to use pip to install GPIO Zero instead. Install pip using get-pip and then type:

pi@raspberrypi:~$ sudo pip3 install gpiozero

or for Python 2:

pi@raspberrypi:~$ sudo pip install gpiozero

To install GPIO Zero in a virtual environment, see the Development page.

PC/Mac¶

In order to use GPIO Zero’s remote GPIO feature from a PC or Mac, you’ll need to install GPIO Zero on that computer using pip. See the Configuring Remote GPIO page for more information.

Documentation¶

This documentation is also available for offline installation like so:

pi@raspberrypi:~$ sudo apt install python-gpiozero-doc

This will install the HTML version of the documentation under the /usr/share/doc/python-gpiozero-doc/html path. To view the offline documentation you have several options:

You can open the documentation directly by visiting file:///usr/share/doc/python-gpiozero-doc/html/index.html in your browser. However, be aware that using file:// URLs sometimes breaks certain elements. To avoid this, you can view the docs from an http:// style URL by starting a trivial HTTP server with Python, like so:

$ python3 -m http.server -d /usr/share/doc/python-gpiozero-doc/html

Then visit http://localhost:8000/ in your browser.

Alternatively, the package also integrates into Debian’s doc-base system, so you can install one of the doc-base clients (dochelp, dwww, dhelp, doc-central, etc.) and use its interface to locate this document.

If you want to view the documentation offline on a different device, such as an eReader, there are Epub and PDF versions of the documentation available for download from the ReadTheDocs site. Simply click on the “Read the Docs” box at the bottom-left corner of the page (under the table of contents) and select “PDF” or “Epub” from the “Downloads” section.

Basic Recipes¶

The following recipes demonstrate some of the capabilities of the GPIO Zero library. Please note that all recipes are written assuming Python 3. Recipes may work under Python 2, but no guarantees!

Importing GPIO Zero¶

In Python, libraries and functions used in a script must be imported by name at the top of the file, with the exception of the functions built into Python by default.

For example, to use the Button interface from GPIO Zero, it should be explicitly imported:

from gpiozero import Button

Now Button is available directly in your script:

button = Button(2)

Alternatively, the whole GPIO Zero library can be imported:

import gpiozero

In this case, all references to items within GPIO Zero must be prefixed:

button = gpiozero.Button(2)

Pin Numbering¶

This library uses Broadcom (BCM) pin numbering for the GPIO pins, as opposed to physical (BOARD) numbering. Unlike in the RPi.GPIO library, this is not configurable. However, translation from other schemes can be used by providing prefixes to pin numbers (see below).

Any pin marked “GPIO” in the diagram below can be used as a pin number. For example, if an LED was attached to “GPIO17” you would specify the pin number as 17 rather than 11:

If you wish to use physical (BOARD) numbering you can specify the pin number as “BOARD11”. If you are familiar with the wiringPi pin numbers (another physical layout) you could use “WPI0” instead. Finally, you can specify pins as “header:number”, e.g. “J8:11” meaning physical pin 11 on header J8 (the GPIO header on modern Pis). Hence, the following lines are all equivalent:

>>> led = LED(17)
>>> led = LED("GPIO17")
>>> led = LED("BCM17")
>>> led = LED("BOARD11")
>>> led = LED("WPI0")
>>> led = LED("J8:11")

Note that these alternate schemes are merely translations. If you request the state of a device on the command line, the associated pin number will always be reported in the Broadcom (BCM) scheme:

>>> led = LED("BOARD11")
>>> led
<gpiozero.LED object on pin GPIO17, active_high=True, is_active=False>

Throughout this manual we will use the default integer pin numbers, in the Broadcom (BCM) layout shown above.

LED¶

Turn an LED on and off repeatedly:

from gpiozero import LED
from time import sleep

red = LED(17)

while True:
    red.on()
    sleep(1)
    red.off()
    sleep(1)

Alternatively:

from gpiozero import LED
from signal import pause

red = LED(17)

red.blink()

pause()

Note

Reaching the end of a Python script will terminate the process and GPIOs may be reset. Keep your script alive with signal.pause(). See How do I keep my script running? for more information.

LED with variable brightness¶

Any regular LED can have its brightness value set using PWM (pulse-width-modulation). In GPIO Zero, this can be achieved using PWMLED using values between 0 and 1:

from gpiozero import PWMLED
from time import sleep

led = PWMLED(17)

while True:
    led.value = 0  # off
    sleep(1)
    led.value = 0.5  # half brightness
    sleep(1)
    led.value = 1  # full brightness
    sleep(1)

Similarly to blinking on and off continuously, a PWMLED can pulse (fade in and out continuously):

from gpiozero import PWMLED
from signal import pause

led = PWMLED(17)

led.pulse()

pause()

Button¶

Check if a Button is pressed:

from gpiozero import Button

button = Button(2)

while True:
    if button.is_pressed:
        print("Button is pressed")
    else:
        print("Button is not pressed")

Wait for a button to be pressed before continuing:

from gpiozero import Button

button = Button(2)

button.wait_for_press()
print("Button was pressed")

Run a function every time the button is pressed:

from gpiozero import Button
from signal import pause

def say_hello():
    print("Hello!")

button = Button(2)

button.when_pressed = say_hello

pause()

Note

Note that the line button.when_pressed = say_hello does not run the function say_hello, rather it creates a reference to the function to be called when the button is pressed. Accidental use of button.when_pressed = say_hello() would set the when_pressed action to None (the return value of this function) which would mean nothing happens when the button is pressed.

Similarly, functions can be attached to button releases:

from gpiozero import Button
from signal import pause

def say_hello():
    print("Hello!")

def say_goodbye():
    print("Goodbye!")

button = Button(2)

button.when_pressed = say_hello
button.when_released = say_goodbye

pause()

Button controlled LED¶

Turn on an LED when a Button is pressed:

from gpiozero import LED, Button
from signal import pause

led = LED(17)
button = Button(2)

button.when_pressed = led.on
button.when_released = led.off

pause()

Alternatively:

from gpiozero import LED, Button
from signal import pause

led = LED(17)
button = Button(2)

led.source = button

pause()

Button controlled camera¶

Using the button press to trigger PiCamera to take a picture using button.when_pressed = camera.capture would not work because the capture() method requires an output parameter. However, this can be achieved using a custom function which requires no parameters:

from gpiozero import Button
from picamera import PiCamera
from datetime import datetime
from signal import pause

button = Button(2)
camera = PiCamera()

def capture():
    timestamp = datetime.now().isoformat()
    camera.capture('/home/pi/%s.jpg' % timestamp)

button.when_pressed = capture

pause()

Another example could use one button to start and stop the camera preview, and another to capture:

from gpiozero import Button
from picamera import PiCamera
from datetime import datetime
from signal import pause

left_button = Button(2)
right_button = Button(3)
camera = PiCamera()

def capture():
    timestamp = datetime.now().isoformat()
    camera.capture('/home/pi/%s.jpg' % timestamp)

left_button.when_pressed = camera.start_preview
left_button.when_released = camera.stop_preview
right_button.when_pressed = capture

pause()

Shutdown button¶

The Button class also provides the ability to run a function when the button has been held for a given length of time. This example will shut down the Raspberry Pi when the button is held for 2 seconds:

from gpiozero import Button
from subprocess import check_call
from signal import pause

def shutdown():
    check_call(['sudo', 'poweroff'])

shutdown_btn = Button(17, hold_time=2)
shutdown_btn.when_held = shutdown

pause()

LEDBoard¶

A collection of LEDs can be accessed using LEDBoard:

from gpiozero import LEDBoard
from time import sleep
from signal import pause

leds = LEDBoard(5, 6, 13, 19, 26)

leds.on()
sleep(1)
leds.off()
sleep(1)
leds.value = (1, 0, 1, 0, 1)
sleep(1)
leds.blink()

pause()

Using LEDBoard with pwm=True allows each LED’s brightness to be controlled:

from gpiozero import LEDBoard
from signal import pause

leds = LEDBoard(5, 6, 13, 19, 26, pwm=True)

leds.value = (0.2, 0.4, 0.6, 0.8, 1.0)

pause()

See more LEDBoard examples in the advanced LEDBoard recipes.

LEDBarGraph¶

A collection of LEDs can be treated like a bar graph using LEDBarGraph:

from gpiozero import LEDBarGraph
from time import sleep
from __future__ import division  # required for python 2

graph = LEDBarGraph(5, 6, 13, 19, 26, 20)

graph.value = 1  # (1, 1, 1, 1, 1, 1)
sleep(1)
graph.value = 1/2  # (1, 1, 1, 0, 0, 0)
sleep(1)
graph.value = -1/2  # (0, 0, 0, 1, 1, 1)
sleep(1)
graph.value = 1/4  # (1, 0, 0, 0, 0, 0)
sleep(1)
graph.value = -1  # (1, 1, 1, 1, 1, 1)
sleep(1)

Note values are essentially rounded to account for the fact LEDs can only be on or off when pwm=False (the default).

However, using LEDBarGraph with pwm=True allows more precise values using LED brightness:

from gpiozero import LEDBarGraph
from time import sleep
from __future__ import division  # required for python 2

graph = LEDBarGraph(5, 6, 13, 19, 26, pwm=True)

graph.value = 1/10  # (0.5, 0, 0, 0, 0)
sleep(1)
graph.value = 3/10  # (1, 0.5, 0, 0, 0)
sleep(1)
graph.value = -3/10  # (0, 0, 0, 0.5, 1)
sleep(1)
graph.value = 9/10  # (1, 1, 1, 1, 0.5)
sleep(1)
graph.value = 95/100  # (1, 1, 1, 1, 0.75)
sleep(1)

LEDCharDisplay¶

A common 7-segment display can be used to represent a variety of characters using LEDCharDisplay (which actually supports an arbitrary number of segments):

from gpiozero import LEDCharDisplay
from time import sleep

display = LEDCharDisplay(21, 20, 16, 22, 23, 24, 12, dp=25)

for char in '321GO':
    display.value = char
    sleep(1)

display.off()

Alternatively:

from gpiozero import LEDCharDisplay
from signal import pause

display = LEDCharDisplay(21, 20, 16, 22, 23, 24, 12, dp=25)
display.source_delay = 1
display.source = '321GO '

pause()

See a multi-character example in the advanced recipes chapter.

Traffic Lights¶

A full traffic lights system.

Using a TrafficLights kit like Pi-Stop:

from gpiozero import TrafficLights
from time import sleep

lights = TrafficLights(2, 3, 4)

lights.green.on()

while True:
    sleep(10)
    lights.green.off()
    lights.amber.on()
    sleep(1)
    lights.amber.off()
    lights.red.on()
    sleep(10)
    lights.amber.on()
    sleep(1)
    lights.green.on()
    lights.amber.off()
    lights.red.off()

Alternatively:

from gpiozero import TrafficLights
from time import sleep
from signal import pause

lights = TrafficLights(2, 3, 4)

def traffic_light_sequence():
    while True:
        yield (0, 0, 1) # green
        sleep(10)
        yield (0, 1, 0) # amber
        sleep(1)
        yield (1, 0, 0) # red
        sleep(10)
        yield (1, 1, 0) # red+amber
        sleep(1)

lights.source = traffic_light_sequence()

pause()

Using LED components:

from gpiozero import LED
from time import sleep

red = LED(2)
amber = LED(3)
green = LED(4)

green.on()
amber.off()
red.off()

while True:
    sleep(10)
    green.off()
    amber.on()
    sleep(1)
    amber.off()
    red.on()
    sleep(10)
    amber.on()
    sleep(1)
    green.on()
    amber.off()
    red.off()

Push button stop motion¶

Capture a picture with the camera module every time a button is pressed:

from gpiozero import Button
from picamera import PiCamera

button = Button(2)
camera = PiCamera()

camera.start_preview()
frame = 1
while True:
    button.wait_for_press()
    camera.capture('/home/pi/frame%03d.jpg' % frame)
    frame += 1

See Push Button Stop Motion for a full resource.

Reaction Game¶

When you see the light come on, the first person to press their button wins!

from gpiozero import Button, LED
from time import sleep
import random

led = LED(17)

player_1 = Button(2)
player_2 = Button(3)

time = random.uniform(5, 10)
sleep(time)
led.on()

while True:
    if player_1.is_pressed:
        print("Player 1 wins!")
        break
    if player_2.is_pressed:
        print("Player 2 wins!")
        break

led.off()

See Quick Reaction Game for a full resource.

GPIO Music Box¶

Each button plays a different sound!

from gpiozero import Button
import pygame.mixer
from pygame.mixer import Sound
from signal import pause

pygame.mixer.init()

button_sounds = {
    Button(2): Sound("samples/drum_tom_mid_hard.wav"),
    Button(3): Sound("samples/drum_cymbal_open.wav"),
}

for button, sound in button_sounds.items():
    button.when_pressed = sound.play

pause()

See GPIO Music Box for a full resource.

All on when pressed¶

While the button is pressed down, the buzzer and all the lights come on.

FishDish:

from gpiozero import FishDish
from signal import pause

fish = FishDish()

fish.button.when_pressed = fish.on
fish.button.when_released = fish.off

pause()

Ryanteck TrafficHat:

from gpiozero import TrafficHat
from signal import pause

th = TrafficHat()

th.button.when_pressed = th.on
th.button.when_released = th.off

pause()

Using LED, Buzzer, and Button components:

from gpiozero import LED, Buzzer, Button
from signal import pause

button = Button(2)
buzzer = Buzzer(3)
red = LED(4)
amber = LED(5)
green = LED(6)

things = [red, amber, green, buzzer]

def things_on():
    for thing in things:
        thing.on()

def things_off():
    for thing in things:
        thing.off()

button.when_pressed = things_on
button.when_released = things_off

pause()

Full color LED¶

Making colours with an RGBLED:

from gpiozero import RGBLED
from time import sleep
from __future__ import division  # required for python 2

led = RGBLED(red=9, green=10, blue=11)

led.red = 1  # full red
sleep(1)
led.red = 0.5  # half red
sleep(1)

led.color = (0, 1, 0)  # full green
sleep(1)
led.color = (1, 0, 1)  # magenta
sleep(1)
led.color = (1, 1, 0)  # yellow
sleep(1)
led.color = (0, 1, 1)  # cyan
sleep(1)
led.color = (1, 1, 1)  # white
sleep(1)

led.color = (0, 0, 0)  # off
sleep(1)

# slowly increase intensity of blue
for n in range(100):
    led.blue = n/100
    sleep(0.1)

Motion sensor¶

Light an LED when a MotionSensor detects motion:

from gpiozero import MotionSensor, LED
from signal import pause

pir = MotionSensor(4)
led = LED(16)

pir.when_motion = led.on
pir.when_no_motion = led.off

pause()

Light sensor¶

Have a LightSensor detect light and dark:

from gpiozero import LightSensor

sensor = LightSensor(18)

while True:
    sensor.wait_for_light()
    print("It's light! :)")
    sensor.wait_for_dark()
    print("It's dark :(")

Run a function when the light changes:

from gpiozero import LightSensor, LED
from signal import pause

sensor = LightSensor(18)
led = LED(16)

sensor.when_dark = led.on
sensor.when_light = led.off

pause()

Or make a PWMLED change brightness according to the detected light level:

from gpiozero import LightSensor, PWMLED
from signal import pause

sensor = LightSensor(18)
led = PWMLED(16)

led.source = sensor

pause()

Distance sensor¶

Note

In the diagram above, the wires leading from the sensor to the breadboard can be omitted; simply plug the sensor directly into the breadboard facing the edge (unfortunately this is difficult to illustrate in the diagram without the sensor’s diagram obscuring most of the breadboard!)

Have a DistanceSensor detect the distance to the nearest object:

from gpiozero import DistanceSensor
from time import sleep

sensor = DistanceSensor(23, 24)

while True:
    print('Distance to nearest object is', sensor.distance, 'm')
    sleep(1)

Run a function when something gets near the sensor:

from gpiozero import DistanceSensor, LED
from signal import pause

sensor = DistanceSensor(23, 24, max_distance=1, threshold_distance=0.2)
led = LED(16)

sensor.when_in_range = led.on
sensor.when_out_of_range = led.off

pause()

Rotary encoder¶

Note

In this recipe, I’ve used a common anode RGB LED. Often, Pi projects use common cathode RGB LEDs because they’re slightly easier to think about electrically. However, in this case all three components can be found in an illuminated rotary encoder which incorporates a common anode RGB LED, and a momentary push button. This is also the reason for the button being wired active-low, contrary to most other examples in this documentation.

For the sake of clarity, the diagram shows the three separate components, but this same circuit will work equally well with this commonly available illuminated rotary encoder instead.

Have a rotary encoder, an RGB LED, and button act as a color picker.

from threading import Event
from colorzero import Color
from gpiozero import RotaryEncoder, RGBLED, Button

rotor = RotaryEncoder(16, 20, wrap=True, max_steps=180)
rotor.steps = -180
led = RGBLED(22, 23, 24, active_high=False)
btn = Button(21, pull_up=False)
led.color = Color('#f00')
done = Event()

def change_hue():
    # Scale the rotor steps (-180..180) to 0..1
    hue = (rotor.steps + 180) / 360
    led.color = Color(h=hue, s=1, v=1)

def show_color():
    print('Hue {led.color.hue.deg:.1f}° = {led.color.html}'.format(led=led))

def stop_script():
    print('Exiting')
    done.set()

print('Select a color by turning the knob')
rotor.when_rotated = change_hue
print('Push the button to see the HTML code for the color')
btn.when_released = show_color
print('Hold the button to exit')
btn.when_held = stop_script
done.wait()

Servo¶

Control a servo between its minimum, mid-point and maximum positions in sequence:

from gpiozero import Servo
from time import sleep

servo = Servo(17)

while True:
    servo.min()
    sleep(2)
    servo.mid()
    sleep(2)
    servo.max()
    sleep(2)

Use a button to control the servo between its minimum and maximum positions:

from gpiozero import Servo, Button

servo = Servo(17)
btn = Button(14)

while True:
    servo.min()
    btn.wait_for_press()
    servo.max()
    btn.wait_for_press()

Automate the servo to continuously slowly sweep:

from gpiozero import Servo
from gpiozero.tools import sin_values
from signal import pause

servo = Servo(17)

servo.source = sin_values()
servo.source_delay = 0.1

pause()

Use AngularServo so you can specify an angle:

from gpiozero import AngularServo
from time import sleep

servo = AngularServo(17, min_angle=-90, max_angle=90)

while True:
    servo.angle = -90
    sleep(2)
    servo.angle = -45
    sleep(2)
    servo.angle = 0
    sleep(2)
    servo.angle = 45
    sleep(2)
    servo.angle = 90
    sleep(2)

Motors¶

Spin a Motor around forwards and backwards:

from gpiozero import Motor
from time import sleep

motor = Motor(forward=4, backward=14)

while True:
    motor.forward()
    sleep(5)
    motor.backward()
    sleep(5)

Robot¶

Make a Robot drive around in (roughly) a square:

from gpiozero import Robot
from time import sleep

robot = Robot(left=(4, 14), right=(17, 18))

for i in range(4):
    robot.forward()
    sleep(10)
    robot.right()
    sleep(1)

Make a robot with a distance sensor that runs away when things get within 20cm of it:

from gpiozero import Robot, DistanceSensor
from signal import pause

sensor = DistanceSensor(23, 24, max_distance=1, threshold_distance=0.2)
robot = Robot(left=(4, 14), right=(17, 18))

sensor.when_in_range = robot.backward
sensor.when_out_of_range = robot.stop
pause()

Button controlled robot¶

Use four GPIO buttons as forward/back/left/right controls for a robot:

from gpiozero import Robot, Button
from signal import pause

robot = Robot(left=(4, 14), right=(17, 18))

left = Button(26)
right = Button(16)
fw = Button(21)
bw = Button(20)

fw.when_pressed = robot.forward
fw.when_released = robot.stop

left.when_pressed = robot.left
left.when_released = robot.stop

right.when_pressed = robot.right
right.when_released = robot.stop

bw.when_pressed = robot.backward
bw.when_released = robot.stop

pause()

Keyboard controlled robot¶

Use up/down/left/right keys to control a robot:

import curses
from gpiozero import Robot

robot = Robot(left=(4, 14), right=(17, 18))

actions = {
    curses.KEY_UP:    robot.forward,
    curses.KEY_DOWN:  robot.backward,
    curses.KEY_LEFT:  robot.left,
    curses.KEY_RIGHT: robot.right,
}

def main(window):
    next_key = None
    while True:
        curses.halfdelay(1)
        if next_key is None:
            key = window.getch()
        else:
            key = next_key
            next_key = None
        if key != -1:
            # KEY PRESSED
            curses.halfdelay(3)
            action = actions.get(key)
            if action is not None:
                action()
            next_key = key
            while next_key == key:
                next_key = window.getch()
            # KEY RELEASED
            robot.stop()

curses.wrapper(main)

Note

This recipe uses the standard curses module. This module requires that Python is running in a terminal in order to work correctly, hence this recipe will not work in environments like IDLE.

If you prefer a version that works under IDLE, the following recipe should suffice:

from gpiozero import Robot
from evdev import InputDevice, list_devices, ecodes

robot = Robot(left=(4, 14), right=(17, 18))

# Get the list of available input devices
devices = [InputDevice(device) for device in list_devices()]
# Filter out everything that's not a keyboard. Keyboards are defined as any
# device which has keys, and which specifically has keys 1..31 (roughly Esc,
# the numeric keys, the first row of QWERTY plus a few more) and which does
# *not* have key 0 (reserved)
must_have = {i for i in range(1, 32)}
must_not_have = {0}
devices = [
    dev
    for dev in devices
    for keys in (set(dev.capabilities().get(ecodes.EV_KEY, [])),)
    if must_have.issubset(keys)
    and must_not_have.isdisjoint(keys)
]
# Pick the first keyboard
keyboard = devices[0]

keypress_actions = {
    ecodes.KEY_UP: robot.forward,
    ecodes.KEY_DOWN: robot.backward,
    ecodes.KEY_LEFT: robot.left,
    ecodes.KEY_RIGHT: robot.right,
}

for event in keyboard.read_loop():
    if event.type == ecodes.EV_KEY and event.code in keypress_actions:
        if event.value == 1:  # key pressed
            keypress_actions[event.code]()
        if event.value == 0:  # key released
            robot.stop()

Note

This recipe uses the third-party evdev module. Install this library with sudo pip3 install evdev first. Be aware that evdev will only work with local input devices; this recipe will not work over SSH.

Motion sensor robot¶

Make a robot drive forward when it detects motion:

from gpiozero import Robot, MotionSensor
from signal import pause

robot = Robot(left=(4, 14), right=(17, 18))
pir = MotionSensor(5)

pir.when_motion = robot.forward
pir.when_no_motion = robot.stop

pause()

Alternatively:

from gpiozero import Robot, MotionSensor
from gpiozero.tools import zip_values
from signal import pause

robot = Robot(left=(4, 14), right=(17, 18))
pir = MotionSensor(5)

robot.source = zip_values(pir, pir)

pause()

Potentiometer¶

Continually print the value of a potentiometer (values between 0 and 1) connected to a MCP3008 analog to digital converter:

from gpiozero import MCP3008

pot = MCP3008(channel=0)

while True:
    print(pot.value)

Present the value of a potentiometer on an LED bar graph using PWM to represent states that won’t “fill” an LED:

from gpiozero import LEDBarGraph, MCP3008
from signal import pause

graph = LEDBarGraph(5, 6, 13, 19, 26, pwm=True)
pot = MCP3008(channel=0)

graph.source = pot

pause()

Measure temperature with an ADC¶

Wire a TMP36 temperature sensor to the first channel of an MCP3008 analog to digital converter:

from gpiozero import MCP3008
from time import sleep

def convert_temp(gen):
    for value in gen:
        yield (value * 3.3 - 0.5) * 100

adc = MCP3008(channel=0)

for temp in convert_temp(adc.values):
    print('The temperature is', temp, 'C')
    sleep(1)

Full color LED controlled by 3 potentiometers¶

Wire up three potentiometers (for red, green and blue) and use each of their values to make up the colour of the LED:

from gpiozero import RGBLED, MCP3008

led = RGBLED(red=2, green=3, blue=4)
red_pot = MCP3008(channel=0)
green_pot = MCP3008(channel=1)
blue_pot = MCP3008(channel=2)

while True:
    led.red = red_pot.value
    led.green = green_pot.value
    led.blue = blue_pot.value

Alternatively, the following example is identical, but uses the source property rather than a while loop:

from gpiozero import RGBLED, MCP3008
from gpiozero.tools import zip_values
from signal import pause

led = RGBLED(2, 3, 4)
red_pot = MCP3008(0)
green_pot = MCP3008(1)
blue_pot = MCP3008(2)

led.source = zip_values(red_pot, green_pot, blue_pot)

pause()

Timed heat lamp¶

If you have a pet (e.g. a tortoise) which requires a heat lamp to be switched on for a certain amount of time each day, you can use an Energenie Pi-mote to remotely control the lamp, and the TimeOfDay class to control the timing:

from gpiozero import Energenie, TimeOfDay
from datetime import time
from signal import pause

lamp = Energenie(1)
daytime = TimeOfDay(time(8), time(20))

daytime.when_activated = lamp.on
daytime.when_deactivated = lamp.off

pause()

Internet connection status indicator¶

You can use a pair of green and red LEDs to indicate whether or not your internet connection is working. Simply use the PingServer class to identify whether a ping to google.com is successful. If successful, the green LED is lit, and if not, the red LED is lit:

from gpiozero import LED, PingServer
from gpiozero.tools import negated
from signal import pause

green = LED(17)
red = LED(18)

google = PingServer('google.com')

google.when_activated = green.on
google.when_deactivated = green.off
red.source = negated(green)

pause()

CPU Temperature Bar Graph¶

You can read the Raspberry Pi’s own CPU temperature using the built-in CPUTemperature class, and display this on a “bar graph” of LEDs:

from gpiozero import LEDBarGraph, CPUTemperature
from signal import pause

cpu = CPUTemperature(min_temp=50, max_temp=90)
leds = LEDBarGraph(2, 3, 4, 5, 6, 7, 8, pwm=True)

leds.source = cpu

pause()

More recipes¶

Continue to:

Advanced Recipes¶

The following recipes demonstrate some of the capabilities of the GPIO Zero library. Please note that all recipes are written assuming Python 3. Recipes may work under Python 2, but no guarantees!

LEDBoard¶

You can iterate over the LEDs in a LEDBoard object one-by-one:

from gpiozero import LEDBoard
from time import sleep

leds = LEDBoard(5, 6, 13, 19, 26)

for led in leds:
    led.on()
    sleep(1)
    led.off()

LEDBoard also supports indexing. This means you can access the individual LED objects using leds[i] where i is an integer from 0 up to (not including) the number of LEDs:

from gpiozero import LEDBoard
from time import sleep

leds = LEDBoard(2, 3, 4, 5, 6, 7, 8, 9)

leds[0].on()  # first led on
sleep(1)
leds[7].on()  # last led on
sleep(1)
leds[-1].off()  # last led off
sleep(1)

This also means you can use slicing to access a subset of the LEDs:

from gpiozero import LEDBoard
from time import sleep

leds = LEDBoard(2, 3, 4, 5, 6, 7, 8, 9)

for led in leds[3:]:  # leds 3 and onward
    led.on()
sleep(1)
leds.off()

for led in leds[:2]:  # leds 0 and 1
    led.on()
sleep(1)
leds.off()

for led in leds[::2]:  # even leds (0, 2, 4...)
    led.on()
sleep(1)
leds.off()

for led in leds[1::2]:  # odd leds (1, 3, 5...)
    led.on()
sleep(1)
leds.off()

LEDBoard objects can have their LED objects named upon construction. This means the individual LEDs can be accessed by their name:

from gpiozero import LEDBoard
from time import sleep

leds = LEDBoard(red=2, green=3, blue=4)

leds.red.on()
sleep(1)
leds.green.on()
sleep(1)
leds.blue.on()
sleep(1)

LEDBoard objects can also be nested within other LEDBoard objects:

from gpiozero import LEDBoard
from time import sleep

leds = LEDBoard(red=LEDBoard(top=2, bottom=3), green=LEDBoard(top=4, bottom=5))

leds.red.on() ## both reds on
sleep(1)
leds.green.on()  # both greens on
sleep(1)
leds.off()  # all off
sleep(1)
leds.red.top.on()  # top red on
sleep(1)
leds.green.bottom.on()  # bottom green on
sleep(1)

Multi-character 7-segment display¶

The 7-segment display demonstrated in the previous chapter is often available in multi-character variants (typically 4 characters long). Such displays are multiplexed meaning that the LED pins are typically the same as for the single character display but are shared across all characters. Each character in turn then has its own common line which can be tied to ground (in the case of a common cathode display) to enable that particular character. By activating each character in turn very quickly, the eye can be fooled into thinking four different characters are being displayed simultaneously.

In such circuits you should not attempt to sink all the current from a single character (which may have up to 8 LEDs, in the case of a decimal-point, active) into a single GPIO. Rather, use some appropriate transistor (or similar component, e.g. an opto-coupler) to tie the digit’s cathode to ground, and control that component from a GPIO.

This circuit demonstrates a 4-character 7-segment (actually 8-segment, with decimal-point) display, controlled by the Pi’s GPIOs with 4 2N-3904 NPN transistors to control the digits.

Warning

You are strongly advised to check the data-sheet for your particular multi-character 7-segment display. The pin-outs of these displays vary significantly and are very likely to be different to that shown on the breadboard above. For this reason, the schematic for this circuit is provided below; adapt it to your particular display.

The following code can be used to scroll a message across the display:

from itertools import cycle
from collections import deque
from gpiozero import LEDMultiCharDisplay
from signal import pause

display = LEDMultiCharDisplay(
    LEDCharDisplay(22, 23, 24, 25, 21, 20, 16, dp=12), 26, 19, 13, 6)

def scroller(message, chars=4):
    d = deque(maxlen=chars)
    for c in cycle(message):
        d.append(c)
        if len(d) == chars:
            yield ''.join(d)

display.source_delay = 0.2
display.source = scroller('GPIO 2ER0    ')
pause()

Who’s home indicator¶

Using a number of green-red LED pairs, you can show the status of who’s home, according to which IP addresses you can ping successfully. Note that this assumes each person’s mobile phone has a reserved IP address on the home router.

from gpiozero import PingServer, LEDBoard
from gpiozero.tools import negated
from signal import pause

status = LEDBoard(
    mum=LEDBoard(red=14, green=15),
    dad=LEDBoard(red=17, green=18),
    alice=LEDBoard(red=21, green=22)
)

statuses = {
    PingServer('192.168.1.5'): status.mum,
    PingServer('192.168.1.6'): status.dad,
    PingServer('192.168.1.7'): status.alice,
}

for server, leds in statuses.items():
    leds.green.source = server
    leds.green.source_delay = 60
    leds.red.source = negated(leds.green)

pause()

Alternatively, using the STATUS Zero board:

from gpiozero import PingServer, StatusZero
from gpiozero.tools import negated
from signal import pause

status = StatusZero('mum', 'dad', 'alice')

statuses = {
    PingServer('192.168.1.5'): status.mum,
    PingServer('192.168.1.6'): status.dad,
    PingServer('192.168.1.7'): status.alice,
}

for server, leds in statuses.items():
    leds.green.source = server
    leds.green.source_delay = 60
    leds.red.source = negated(leds.green)

pause()

Travis build LED indicator¶

Use LEDs to indicate the status of a Travis build. A green light means the tests are passing, a red light means the build is broken:

from travispy import TravisPy
from gpiozero import LED
from gpiozero.tools import negated
from time import sleep
from signal import pause

def build_passed(repo):
    t = TravisPy()
    r = t.repo(repo)
    while True:
        yield r.last_build_state == 'passed'

red = LED(12)
green = LED(16)

green.source = build_passed('gpiozero/gpiozero')
green.source_delay = 60 * 5  # check every 5 minutes
red.source = negated(green)

pause()

Note this recipe requires travispy. Install with sudo pip3 install travispy.

Button controlled robot¶

Alternatively to the examples in the simple recipes, you can use four buttons to program the directions and add a fifth button to process them in turn, like a Bee-Bot or Turtle robot.

from gpiozero import Button, Robot
from time import sleep
from signal import pause

robot = Robot((17, 18), (22, 23))

left = Button(2)
right = Button(3)
forward = Button(4)
backward = Button(5)
go = Button(6)

instructions = []

def add_instruction(btn):
    instructions.append({
        left:     (-1, 1),
        right:    (1, -1),
        forward:  (1, 1),
        backward: (-1, -1),
    }[btn])

def do_instructions():
    instructions.append((0, 0))
    robot.source_delay = 0.5
    robot.source = instructions
    sleep(robot.source_delay * len(instructions))
    del instructions[:]

go.when_pressed = do_instructions
for button in (left, right, forward, backward):
    button.when_pressed = add_instruction

pause()

Robot controlled by 2 potentiometers¶

Use two potentiometers to control the left and right motor speed of a robot:

from gpiozero import Robot, MCP3008
from gpiozero.tools import zip_values
from signal import pause

robot = Robot(left=(4, 14), right=(17, 18))

left_pot = MCP3008(0)
right_pot = MCP3008(1)

robot.source = zip_values(left_pot, right_pot)

pause()

To include reverse direction, scale the potentiometer values from 0->1 to -1->1:

from gpiozero import Robot, MCP3008
from gpiozero.tools import scaled
from signal import pause

robot = Robot(left=(4, 14), right=(17, 18))

left_pot = MCP3008(0)
right_pot = MCP3008(1)

robot.source = zip(scaled(left_pot, -1, 1), scaled(right_pot, -1, 1))

pause()

Note

Please note the example above requires Python 3. In Python 2, zip() doesn’t support lazy evaluation so the script will simply hang.

BlueDot LED¶

BlueDot is a Python library an Android app which allows you to easily add Bluetooth control to your Raspberry Pi project. A simple example to control a LED using the BlueDot app:

from bluedot import BlueDot
from gpiozero import LED

bd = BlueDot()
led = LED(17)

while True:
    bd.wait_for_press()
    led.on()
    bd.wait_for_release()
    led.off()

Note this recipe requires bluedot and the associated Android app. See the BlueDot documentation for installation instructions.

BlueDot robot¶

You can create a Bluetooth controlled robot which moves forward when the dot is pressed and stops when it is released:

from bluedot import BlueDot
from gpiozero import Robot
from signal import pause

bd = BlueDot()
robot = Robot(left=(4, 14), right=(17, 18))

def move(pos):
    if pos.top:
        robot.forward(pos.distance)
    elif pos.bottom:
        robot.backward(pos.distance)
    elif pos.left:
        robot.left(pos.distance)
    elif pos.right:
        robot.right(pos.distance)

bd.when_pressed = move
bd.when_moved = move
bd.when_released = robot.stop

pause()

Or a more advanced example including controlling the robot’s speed and precise direction:

from gpiozero import Robot
from bluedot import BlueDot
from signal import pause

def pos_to_values(x, y):
    left = y if x > 0 else y + x
    right = y if x < 0 else y - x
    return (clamped(left), clamped(right))

def clamped(v):
    return max(-1, min(1, v))

def drive():
    while True:
        if bd.is_pressed:
            x, y = bd.position.x, bd.position.y
            yield pos_to_values(x, y)
        else:
            yield (0, 0)

robot = Robot(left=(4, 14), right=(17, 18))
bd = BlueDot()

robot.source = drive()

pause()

Controlling the Pi’s own LEDs¶

On certain models of Pi (specifically the model A+, B+, and 2B) it’s possible to control the power and activity LEDs. This can be useful for testing GPIO functionality without the need to wire up your own LEDs (also useful because the power and activity LEDs are “known good”).

Firstly you need to disable the usual triggers for the built-in LEDs. This can be done from the terminal with the following commands:

$ echo none | sudo tee /sys/class/leds/led0/trigger
$ echo gpio | sudo tee /sys/class/leds/led1/trigger

Now you can control the LEDs with gpiozero like so:

from gpiozero import LED
from signal import pause

power = LED(35) # /sys/class/leds/led1
activity = LED(47) # /sys/class/leds/led0

activity.blink()
power.blink()
pause()

To revert the LEDs to their usual purpose you can either reboot your Pi or run the following commands:

$ echo mmc0 | sudo tee /sys/class/leds/led0/trigger
$ echo input | sudo tee /sys/class/leds/led1/trigger

Note

On the Pi Zero you can control the activity LED with this recipe, but there’s no separate power LED to control (it’s also worth noting the activity LED is active low, so set active_high=False when constructing your LED component).

On the original Pi 1 (model A or B), the activity LED can be controlled with GPIO16 (after disabling its trigger as above) but the power LED is hard-wired on.

On the Pi 3 the LEDs are controlled by a GPIO expander which is not accessible from gpiozero (yet).

Configuring Remote GPIO¶

GPIO Zero supports a number of different pin implementations (low-level pin libraries which deal with the GPIO pins directly). By default, the RPi.GPIO library is used (assuming it is installed on your system), but you can optionally specify one to use. For more information, see the API - Pins documentation page.

One of the pin libraries supported, pigpio, provides the ability to control GPIO pins remotely over the network, which means you can use GPIO Zero to control devices connected to a Raspberry Pi on the network. You can do this from another Raspberry Pi, or even from a PC.

See the Remote GPIO Recipes page for examples on how remote pins can be used.

Preparing the Raspberry Pi¶

If you’re using Raspberry Pi OS (desktop - not Lite) then you have everything you need to use the remote GPIO feature. If you’re using Raspberry Pi OS Lite, or another distribution, you’ll need to install pigpio:

$ sudo apt install pigpio

Alternatively, pigpio is available from abyz.me.uk.

You’ll need to enable remote connections, and launch the pigpio daemon on the Raspberry Pi.

Enable remote connections¶

On the Raspberry Pi OS desktop image, you can enable Remote GPIO in the Raspberry Pi configuration tool:

Alternatively, enter sudo raspi-config on the command line, and enable Remote GPIO. This is functionally equivalent to the desktop method.

This will allow remote connections (until disabled) when the pigpio daemon is launched using systemctl (see below). It will also launch the pigpio daemon for the current session. Therefore, nothing further is required for the current session, but after a reboot, a systemctl command will be required.

Command-line: systemctl¶

To automate running the daemon at boot time, run:

$ sudo systemctl enable pigpiod

To run the daemon once using systemctl, run:

$ sudo systemctl start pigpiod

Command-line: pigpiod¶

Another option is to launch the pigpio daemon manually:

$ sudo pigpiod

This is for single-session-use and will not persist after a reboot. However, this method can be used to allow connections from a specific IP address, using the -n flag. For example:

$ sudo pigpiod -n localhost # allow localhost only
$ sudo pigpiod -n 192.168.1.65 # allow 192.168.1.65 only
$ sudo pigpiod -n localhost -n 192.168.1.65 # allow localhost and 192.168.1.65 only

Note

Note that running sudo pigpiod will not honour the Remote GPIO configuration setting (i.e. without the -n flag it will allow remote connections even if the remote setting is disabled), but sudo systemctl enable pigpiod or sudo systemctl start pigpiod will not allow remote connections unless configured accordingly.

Preparing the control computer¶

If the control computer (the computer you’re running your Python code from) is a Raspberry Pi running Raspberry Pi OS (or a PC running Raspberry Pi Desktop x86), then you have everything you need. If you’re using another Linux distribution, Mac OS or Windows then you’ll need to install the pigpio Python library on the PC.

Raspberry Pi¶

First, update your repositories list:

$ sudo apt update

Then install GPIO Zero and the pigpio library for Python 3:

$ sudo apt install python3-gpiozero python3-pigpio

or Python 2:

$ sudo apt install python-gpiozero python-pigpio

Alternatively, install with pip:

$ sudo pip3 install gpiozero pigpio

or for Python 2:

$ sudo pip install gpiozero pigpio

Linux¶

First, update your distribution’s repositories list. For example:

$ sudo apt update

Then install pip for Python 3:

$ sudo apt install python3-pip

or Python 2:

$ sudo apt install python-pip

(Alternatively, install pip with get-pip.)

Next, install GPIO Zero and pigpio for Python 3:

$ sudo pip3 install gpiozero pigpio

or Python 2:

$ sudo pip install gpiozero pigpio

Mac OS¶

First, install pip. If you installed Python 3 using brew, you will already have pip. If not, install pip with get-pip.

Next, install GPIO Zero and pigpio with pip:

$ pip3 install gpiozero pigpio

Or for Python 2:

$ pip install gpiozero pigpio

Windows¶

Modern Python installers for Windows bundle pip with Python. If pip is not installed, you can follow this guide. Next, install GPIO Zero and pigpio with pip:

C:\Users\user1> pip install gpiozero pigpio

Environment variables¶

The simplest way to use devices with remote pins is to set the PIGPIO_ADDR environment variable to the IP address of the desired Raspberry Pi. You must run your Python script or launch your development environment with the environment variable set using the command line. For example, one of the following:

$ PIGPIO_ADDR=192.168.1.3 python3 hello.py
$ PIGPIO_ADDR=192.168.1.3 python3
$ PIGPIO_ADDR=192.168.1.3 ipython3
$ PIGPIO_ADDR=192.168.1.3 idle3 &

If you are running this from a PC (not a Raspberry Pi) with gpiozero and the pigpio Python library installed, this will work with no further configuration. However, if you are running this from a Raspberry Pi, you will also need to ensure the default pin factory is set to PiGPIOFactory. If RPi.GPIO is installed, this will be selected as the default pin factory, so either uninstall it, or use the GPIOZERO_PIN_FACTORY environment variable to override it:

$ GPIOZERO_PIN_FACTORY=pigpio PIGPIO_ADDR=192.168.1.3 python3 hello.py

This usage will set the pin factory to PiGPIOFactory with a default host of 192.168.1.3. The pin factory can be changed inline in the code, as seen in the following sections.

With this usage, you can write gpiozero code like you would on a Raspberry Pi, with no modifications needed. For example:

from gpiozero import LED
from time import sleep

red = LED(17)

while True:
    red.on()
    sleep(1)
    red.off()
    sleep(1)

When run with:

$ PIGPIO_ADDR=192.168.1.3 python3 led.py

will flash the LED connected to pin 17 of the Raspberry Pi with the IP address 192.168.1.3. And:

$ PIGPIO_ADDR=192.168.1.4 python3 led.py

will flash the LED connected to pin 17 of the Raspberry Pi with the IP address 192.168.1.4, without any code changes, as long as the Raspberry Pi has the pigpio daemon running.

Note

When running code directly on a Raspberry Pi, any pin factory can be used (assuming the relevant library is installed), but when a device is used remotely, only PiGPIOFactory can be used, as pigpio is the only pin library which supports remote GPIO.

Pin factories¶

An alternative (or additional) method of configuring gpiozero objects to use remote pins is to create instances of PiGPIOFactory objects, and use them when instantiating device objects. For example, with no environment variables set:

from gpiozero import LED
from gpiozero.pins.pigpio import PiGPIOFactory
from time import sleep

factory = PiGPIOFactory(host='192.168.1.3')
led = LED(17, pin_factory=factory)

while True:
    led.on()
    sleep(1)
    led.off()
    sleep(1)

This allows devices on multiple Raspberry Pis to be used in the same script:

from gpiozero import LED
from gpiozero.pins.pigpio import PiGPIOFactory
from time import sleep

factory3 = PiGPIOFactory(host='192.168.1.3')
factory4 = PiGPIOFactory(host='192.168.1.4')
led_1 = LED(17, pin_factory=factory3)
led_2 = LED(17, pin_factory=factory4)

while True:
    led_1.on()
    led_2.off()
    sleep(1)
    led_1.off()
    led_2.on()
    sleep(1)

You can, of course, continue to create gpiozero device objects as normal, and create others using remote pins. For example, if run on a Raspberry Pi, the following script will flash an LED on the controller Pi, and also on another Pi on the network:

from gpiozero import LED
from gpiozero.pins.pigpio import PiGPIOFactory
from time import sleep

remote_factory = PiGPIOFactory(host='192.168.1.3')
led_1 = LED(17)  # local pin
led_2 = LED(17, pin_factory=remote_factory)  # remote pin

while True:
    led_1.on()
    led_2.off()
    sleep(1)
    led_1.off()
    led_2.on()
    sleep(1)

Alternatively, when run with the environment variables GPIOZERO_PIN_FACTORY=pigpio PIGPIO_ADDR=192.168.1.3 set, the following script will behave exactly the same as the previous one:

from gpiozero import LED
from gpiozero.pins.rpigpio import RPiGPIOFactory
from time import sleep

local_factory = RPiGPIOFactory()
led_1 = LED(17, pin_factory=local_factory)  # local pin
led_2 = LED(17)  # remote pin

while True:
    led_1.on()
    led_2.off()
    sleep(1)
    led_1.off()
    led_2.on()
    sleep(1)

Of course, multiple IP addresses can be used:

from gpiozero import LED
from gpiozero.pins.pigpio import PiGPIOFactory
from time import sleep

factory3 = PiGPIOFactory(host='192.168.1.3')
factory4 = PiGPIOFactory(host='192.168.1.4')

led_1 = LED(17)  # local pin
led_2 = LED(17, pin_factory=factory3)  # remote pin on one pi
led_3 = LED(17, pin_factory=factory4)  # remote pin on another pi

while True:
    led_1.on()
    led_2.off()
    led_3.on()
    sleep(1)
    led_1.off()
    led_2.on()
    led_3.off()
    sleep(1)

Note that these examples use the LED class, which takes a pin argument to initialise. Some classes, particularly those representing HATs and other add-on boards, do not require their pin numbers to be specified. However, it is still possible to use remote pins with these devices, either using environment variables, or the pin_factory keyword argument:

import gpiozero
from gpiozero import TrafficHat
from gpiozero.pins.pigpio import PiGPIOFactory
from time import sleep

gpiozero.Device.pin_factory = PiGPIOFactory(host='192.168.1.3')
th = TrafficHat()  # traffic hat on 192.168.1.3 using remote pins

This also allows you to swap between two IP addresses and create instances of multiple HATs connected to different Pis:

import gpiozero
from gpiozero import TrafficHat
from gpiozero.pins.pigpio import PiGPIOFactory
from time import sleep

remote_factory = PiGPIOFactory(host='192.168.1.3')

th_1 = TrafficHat()  # traffic hat using local pins
th_2 = TrafficHat(pin_factory=remote_factory)  # traffic hat on 192.168.1.3 using remote pins

You could even use a HAT which is not supported by GPIO Zero (such as the Sense HAT) on one Pi, and use remote pins to control another over the network:

from gpiozero import MotionSensor
from gpiozero.pins.pigpio import PiGPIOFactory
from sense_hat import SenseHat

remote_factory = PiGPIOFactory(host='192.198.1.4')
pir = MotionSensor(4, pin_factory=remote_factory)  # remote motion sensor
sense = SenseHat()  # local sense hat

while True:
    pir.wait_for_motion()
    sense.show_message(sense.temperature)

Note that in this case, the Sense HAT code must be run locally, and the GPIO remotely.

Remote GPIO usage¶

Continue to:

Remote GPIO Recipes¶

The following recipes demonstrate some of the capabilities of the remote GPIO feature of the GPIO Zero library. Before you start following these examples, please read up on preparing your Pi and your host PC to work with Configuring Remote GPIO.

Please note that all recipes are written assuming Python 3. Recipes may work under Python 2, but no guarantees!

LED + Button¶

Let a Button on one Raspberry Pi control the LED of another:

from gpiozero import Button, LED
from gpiozero.pins.pigpio import PiGPIOFactory
from signal import pause

factory = PiGPIOFactory(host='192.168.1.3')

button = Button(2)
led = LED(17, pin_factory=factory)

led.source = button

pause()

LED + 2 Buttons¶

The LED will come on when both buttons are pressed:

from gpiozero import Button, LED
from gpiozero.pins.pigpio import PiGPIOFactory
from gpiozero.tools import all_values
from signal import pause

factory3 = PiGPIOFactory(host='192.168.1.3')
factory4 = PiGPIOFactory(host='192.168.1.4')

led = LED(17)
button_1 = Button(17, pin_factory=factory3)
button_2 = Button(17, pin_factory=factory4)

led.source = all_values(button_1, button_2)

pause()

Multi-room motion alert¶

Install a Raspberry Pi with a MotionSensor in each room of your house, and have an class:LED indicator showing when there’s motion in each room:

from gpiozero import LEDBoard, MotionSensor
from gpiozero.pins.pigpio import PiGPIOFactory
from gpiozero.tools import zip_values
from signal import pause

ips = ['192.168.1.3', '192.168.1.4', '192.168.1.5', '192.168.1.6']
remotes = [PiGPIOFactory(host=ip) for ip in ips]

leds = LEDBoard(2, 3, 4, 5)  # leds on this pi
sensors = [MotionSensor(17, pin_factory=r) for r in remotes]  # remote sensors

leds.source = zip_values(*sensors)

pause()

Multi-room doorbell¶

Install a Raspberry Pi with a Buzzer attached in each room you want to hear the doorbell, and use a push Button as the doorbell:

from gpiozero import LEDBoard, MotionSensor
from gpiozero.pins.pigpio import PiGPIOFactory
from signal import pause

ips = ['192.168.1.3', '192.168.1.4', '192.168.1.5', '192.168.1.6']
remotes = [PiGPIOFactory(host=ip) for ip in ips]

button = Button(17)  # button on this pi
buzzers = [Buzzer(pin, pin_factory=r) for r in remotes]  # buzzers on remote pins

for buzzer in buzzers:
    buzzer.source = button

pause()

This could also be used as an internal doorbell (tell people it’s time for dinner from the kitchen).

Remote button robot¶

Similarly to the simple recipe for the button controlled Robot, this example uses four buttons to control the direction of a robot. However, using remote pins for the robot means the control buttons can be separate from the robot:

from gpiozero import Button, Robot
from gpiozero.pins.pigpio import PiGPIOFactory
from signal import pause

factory = PiGPIOFactory(host='192.168.1.17')
robot = Robot(left=(4, 14), right=(17, 18), pin_factory=factory)  # remote pins

# local buttons
left = Button(26)
right = Button(16)
fw = Button(21)
bw = Button(20)

fw.when_pressed = robot.forward
fw.when_released = robot.stop

left.when_pressed = robot.left
left.when_released = robot.stop

right.when_pressed = robot.right
right.when_released = robot.stop

bw.when_pressed = robot.backward
bw.when_released = robot.stop

pause()

Light sensor + Sense HAT¶

The Sense HAT (not supported by GPIO Zero) includes temperature, humidity and pressure sensors, but no light sensor. Remote GPIO allows an external LightSensor to be used as well. The Sense HAT LED display can be used to show different colours according to the light levels:

from gpiozero import LightSensor
from gpiozero.pins.pigpio import PiGPIOFactory
from sense_hat import SenseHat

remote_factory = PiGPIOFactory(host='192.168.1.4')
light = LightSensor(4, pin_factory=remote_factory)  # remote motion sensor
sense = SenseHat()  # local sense hat

blue = (0, 0, 255)
yellow = (255, 255, 0)

while True:
    if light.value > 0.5:
        sense.clear(yellow)
    else:
        sense.clear(blue)

Note that in this case, the Sense HAT code must be run locally, and the GPIO remotely.

Pi Zero USB OTG¶

The Raspberry Pi Zero and Pi Zero W feature a USB OTG port, allowing users to configure the device as (amongst other things) an Ethernet device. In this mode, it is possible to control the Pi Zero’s GPIO pins over USB from another computer using the remote GPIO feature.

GPIO expander method - no SD card required¶

The GPIO expander method allows you to boot the Pi Zero over USB from the PC, without an SD card. Your PC sends the required boot firmware to the Pi over the USB cable, launching a mini version of Raspberry Pi OS and booting it in RAM. The OS then starts the pigpio daemon, allowing “remote” access over the USB cable.

At the time of writing, this is only possible using either the Raspberry Pi Desktop x86 OS, or Ubuntu (or a derivative), or from another Raspberry Pi. Usage from Windows and Mac OS is not supported at present.

Raspberry Pi Desktop x86 setup¶

Download an ISO of the Raspberry Pi Desktop OS from raspberrypi.org
Write the image to a USB stick or burn to a DVD.
Live boot your PC or Mac into the OS (select “Run with persistence” and your computer will be back to normal afterwards).

Raspberry Pi setup (using Raspberry Pi OS)¶

Update your package list and install the usbbootgui package:

$ sudo apt update
$ sudo apt install usbbootgui

Ubuntu setup¶

Add the Raspberry Pi PPA to your system:

$ sudo add-apt-repository ppa:rpi-distro/ppa

2. If you have previously installed gpiozero or pigpio with pip, uninstall these first:

$ sudo pip3 uninstall gpiozero pigpio

Install the required packages from the PPA:

$ sudo apt install usbbootgui pigpio python3-gpiozero python3-pigpio

Access the GPIOs¶

Once your PC or Pi has the USB Boot GUI tool installed, connecting a Pi Zero will automatically launch a prompt to select a role for the device. Select “GPIO expansion board” and continue:

It will take 30 seconds or so to flash it, then the dialogue will disappear.

Raspberry Pi OS will name your Pi Zero connection usb0. On Ubuntu, this will likely be something else. You can ping it using the address fe80::1% followed by the connection string. You can look this up using ifconfig.

Set the GPIOZERO_PIN_FACTORY and PIGPIO_ADDR environment variables on your PC so GPIO Zero connects to the “remote” Pi Zero:

$ export GPIOZERO_PIN_FACTORY=pigpio
$ export PIGPIO_ADDR=fe80::1%usb0

Now any GPIO Zero code you run on the PC will use the GPIOs of the attached Pi Zero:

Alternatively, you can set the pin factory in-line, as explained in Configuring Remote GPIO.

Read more on the GPIO expander in blog posts on raspberrypi.org and bennuttall.com.

Legacy method - SD card required¶

The legacy method requires the Pi Zero to have an SD card with Raspberry Pi OS inserted.

Start by creating a Raspberry Pi OS (desktop or lite) SD card, and then configure the boot partition like so:

Edit config.txt and add dtoverlay=dwc2 on a new line, then save the file.
Create an empty file called ssh (no file extension) and save it in the boot partition.
Edit cmdline.txt` and insert modules-load=dwc2,g_ether after rootwait.

(See guides on blog.gbaman.info and learn.adafruit.com for more detailed instructions)

Then connect the Pi Zero to your computer using a micro USB cable (connecting it to the USB port, not the power port). You’ll see the indicator LED flashing as the Pi Zero boots. When it’s ready, you will be able to ping and SSH into it using the hostname raspberrypi.local. SSH into the Pi Zero, install pigpio and run the pigpio daemon.

Then, drop out of the SSH session and you can run Python code on your computer to control devices attached to the Pi Zero, referencing it by its hostname (or IP address if you know it), for example:

$ GPIOZERO_PIN_FACTORY=pigpio PIGPIO_ADDR=raspberrypi.local python3 led.py

Source/Values¶

GPIO Zero provides a method of using the declarative programming paradigm to connect devices together: feeding the values of one device into another, for example the values of a button into an LED:

from gpiozero import LED, Button
from signal import pause

led = LED(17)
button = Button(2)

led.source = button

pause()

which is equivalent to:

from gpiozero import LED, Button
from time import sleep

led = LED(17)
button = Button(2)

while True:
    led.value = button.value
    sleep(0.01)

except that the former is updated in a background thread, which enables you to do other things at the same time.

Every device has a value property (the device’s current value). Input devices (like buttons) can only have their values read, but output devices (like LEDs) can also have their value set to alter the state of the device:

>>> led = PWMLED(17)
>>> led.value  # LED is initially off
0.0
>>> led.on()  # LED is now on
>>> led.value
1.0
>>> led.value = 0  # LED is now off

Every device also has a values property (a generator continuously yielding the device’s current value). All output devices have a source property which can be set to any iterator. The device will iterate over the values of the device provided, setting the device’s value to each element at a rate specified in the source_delay property (the default is 0.01 seconds).

The most common use case for this is to set the source of an output device to match the values of an input device, like the example above. A more interesting example would be a potentiometer controlling the brightness of an LED:

from gpiozero import PWMLED, MCP3008
from signal import pause

led = PWMLED(17)
pot = MCP3008()

led.source = pot

pause()

The way this works is that the input device’s values property is used to feed values into the output device. Prior to v1.5, the source had to be set directly to a device’s values property:

from gpiozero import PWMLED, MCP3008
from signal import pause

led = PWMLED(17)
pot = MCP3008()

led.source = pot.values

pause()

Note

Although this method is still supported, the recommended way is now to set the source to a device object.

It is also possible to set an output device’s source to another output device, to keep them matching. In this example, the red LED is set to match the button, and the green LED is set to match the red LED, so both LEDs will be on when the button is pressed:

from gpiozero import LED, Button
from signal import pause

red = LED(14)
green = LED(15)
button = Button(17)

red.source = button
green.source = red

pause()

Processing values¶

The device’s values can also be processed before they are passed to the source:

For example, writing a generator function to pass the opposite of the Button value into the LED:

from gpiozero import Button, LED
from signal import pause

def opposite(device):
    for value in device.values:
        yield not value

led = LED(4)
btn = Button(17)

led.source = opposite(btn)

pause()

Alternatively, a custom generator can be used to provide values from an artificial source:

For example, writing a generator function to randomly yield 0 or 1:

from gpiozero import LED
from random import randint
from signal import pause

def rand():
    while True:
        yield randint(0, 1)

led = LED(17)
led.source = rand()

pause()

If the iterator is infinite (i.e. an infinite generator), the elements will be processed until the source is changed or set to None.

If the iterator is finite (e.g. a list), this will terminate once all elements are processed (leaving the device’s value at the final element):

from gpiozero import LED
from signal import pause

led = LED(17)
led.source_delay = 1
led.source = [1, 0, 1, 1, 1, 0, 0, 1, 0, 1]

pause()

Source Tools¶

GPIO Zero provides a set of ready-made functions for dealing with source/values, called source tools. These are available by importing from gpiozero.tools.

Some of these source tools are artificial sources which require no input:

In this example, random values between 0 and 1 are passed to the LED, giving it a flickering candle effect:

from gpiozero import PWMLED
from gpiozero.tools import random_values
from signal import pause

led = PWMLED(4)
led.source = random_values()
led.source_delay = 0.1

pause()

Note that in the above example, source_delay is used to make the LED iterate over the random values slightly slower. source_delay can be set to a larger number (e.g. 1 for a one second delay) or set to 0 to disable any delay.

Some tools take a single source and process its values:

In this example, the LED is lit only when the button is not pressed:

from gpiozero import Button, LED
from gpiozero.tools import negated
from signal import pause

led = LED(4)
btn = Button(17)

led.source = negated(btn)

pause()

Note

Note that source tools which take one or more value parameters support passing either ValuesMixin derivatives, or iterators, including a device’s values property.

Some tools combine the values of multiple sources:

In this example, the LED is lit only if both buttons are pressed (like an AND gate):

from gpiozero import Button, LED
from gpiozero.tools import all_values
from signal import pause

button_a = Button(2)
button_b = Button(3)
led = LED(17)

led.source = all_values(button_a, button_b)

pause()

Similarly, any_values() with two buttons would simulate an OR gate.

While most devices have a value range between 0 and 1, some have a range between -1 and 1 (e.g. Motor, Servo and TonalBuzzer). Some source tools output values between -1 and 1, which are ideal for these devices, for example passing sin_values() in:

from gpiozero import Motor, Servo, TonalBuzzer
from gpiozero.tools import sin_values
from signal import pause

motor = Motor(2, 3)
servo = Servo(4)
buzzer = TonalBuzzer(5)

motor.source = sin_values()
servo.source = motor
buzzer.source = motor

pause()

In this example, all three devices are following the sine wave. The motor value ramps up from 0 (stopped) to 1 (full speed forwards), then back down to 0 and on to -1 (full speed backwards) in a cycle. Similarly, the servo moves from its mid point to the right, then towards the left; and the buzzer starts with its mid tone, gradually raises its frequency, to its highest tone, then down towards its lowest tone. Note that setting source_delay will alter the speed at which the device iterates through the values. Alternatively, the tool cos_values() could be used to start from -1 and go up to 1, and so on.

Internal devices¶

GPIO Zero also provides several internal devices which represent facilities provided by the operating system itself. These can be used to react to things like the time of day, or whether a server is available on the network. These classes include a values property which can be used to feed values into a device’s source. For example, a lamp connected to an Energenie socket can be controlled by a TimeOfDay object so that it is on between the hours of 8am and 8pm:

from gpiozero import Energenie, TimeOfDay
from datetime import time
from signal import pause

lamp = Energenie(1)
daytime = TimeOfDay(time(8), time(20))

daytime.when_activated = lamp.on
daytime.when_deactivated = lamp.off

pause()

Using the DiskUsage class with LEDBarGraph can show your Pi’s disk usage percentage on a bar graph:

from gpiozero import DiskUsage, LEDBarGraph
from signal import pause

disk = DiskUsage()
graph = LEDBarGraph(2, 3, 4, 5, 6, 7, 8)

graph.source = disk

pause()

Demonstrating a garden light system whereby the light comes on if it’s dark and there’s motion is simple enough, but it requires using the booleanized() source tool to convert the light sensor from a float value into a boolean:

from gpiozero import LED, MotionSensor, LightSensor
from gpiozero.tools import booleanized, all_values
from signal import pause

garden = LED(2)
motion = MotionSensor(4)
light = LightSensor(5)

garden.source = all_values(booleanized(light, 0, 0.1), motion)

pause()

Composite devices¶

The value of a composite device made up of the nested values of its devices. For example, the value of a Robot object is a 2-tuple containing its left and right motor values:

>>> from gpiozero import Robot
>>> robot = Robot(left=(14, 15), right=(17, 18))
>>> robot.value
RobotValue(left_motor=0.0, right_motor=0.0)
>>> tuple(robot.value)
(0.0, 0.0)
>>> robot.forward()
>>> tuple(robot.value)
(1.0, 1.0)
>>> robot.backward()
>>> tuple(robot.value)
(-1.0, -1.0)
>>> robot.value = (1, 1)  # robot is now driven forwards

Use two potentiometers to control the left and right motor speed of a robot:

from gpiozero import Robot, MCP3008
from gpiozero.tools import zip_values
from signal import pause

robot = Robot(left=(4, 14), right=(17, 18))

left_pot = MCP3008(0)
right_pot = MCP3008(1)

robot.source = zip_values(left_pot, right_pot)

pause()

To include reverse direction, scale the potentiometer values from 0->1 to -1->1:

from gpiozero import Robot, MCP3008
from gpiozero.tools import scaled
from signal import pause

robot = Robot(left=(4, 14), right=(17, 18))

left_pot = MCP3008(0)
right_pot = MCP3008(1)

robot.source = zip(scaled(left_pot, -1, 1), scaled(right_pot, -1, 1))

pause()

Note that this example uses the built-in zip() rather than the tool zip_values() as the scaled() tool yields values which do not need converting, just zipping. Also note that this use of zip() will not work in Python 2, instead use izip.

Command-line Tools¶

The gpiozero package contains a database of information about the various revisions of Raspberry Pi. This is queried by the pinout command-line tool to output details of the GPIO pins available.

Note

Note that only the Python 3 version of the Debian package includes the pinout command line tool, so as not to create a conflict if both versions are installed. If you only installed the python-gpiozero apt package, the pinout tool will not be available. Instead, you can additionally install the python3-gpiozero package, or alternatively install gpiozero using pip.

pinout¶

Synopsis¶

pinout [-h] [-r REVISION] [-c] [-m] [-x]

Description¶

A utility for querying Raspberry Pi GPIO pin-out information. Running pinout on its own will output a board diagram, and GPIO header diagram for the current Raspberry Pi. It is also possible to manually specify a revision of Pi, or (by Configuring Remote GPIO) to output information about a remote Pi.

Options¶

-h, --help¶: show this help message and exit

-r REVISION, --revision REVISION¶: RPi revision. Default is to autodetect revision of current device

-c, --color¶: Force colored output (by default, the output will include ANSI color codes if run in a color-capable terminal). See also --monochrome

-m, --monochrome¶: Force monochrome output. See also --color

-x, --xyz¶: Open pinout.xyz in the default web browser

Examples¶

To output information about the current Raspberry Pi:

$ pinout

For a Raspberry Pi model 3B, this will output something like the following:

,--------------------------------.
| oooooooooooooooooooo J8     +====
| 1ooooooooooooooooooo        | USB
|                             +====
|      Pi Model 3B V1.1          |
|      +----+                 +====
| |D|  |SoC |                 | USB
| |S|  |    |                 +====
| |I|  +----+                    |
|                   |C|     +======
|                   |S|     |   Net
| pwr        |HDMI| |I||A|  +======
`-| |--------|    |----|V|-------'

Revision           : a02082
SoC                : BCM2837
RAM                : 1024Mb
Storage            : MicroSD
USB ports          : 4 (excluding power)
Ethernet ports     : 1
Wi-fi              : True
Bluetooth          : True
Camera ports (CSI) : 1
Display ports (DSI): 1

J8:
   3V3  (1) (2)  5V
 GPIO2  (3) (4)  5V
 GPIO3  (5) (6)  GND
 GPIO4  (7) (8)  GPIO14
   GND  (9) (10) GPIO15
GPIO17 (11) (12) GPIO18
GPIO27 (13) (14) GND
GPIO22 (15) (16) GPIO23
   3V3 (17) (18) GPIO24
GPIO10 (19) (20) GND
 GPIO9 (21) (22) GPIO25
GPIO11 (23) (24) GPIO8
   GND (25) (26) GPIO7
 GPIO0 (27) (28) GPIO1
 GPIO5 (29) (30) GND
 GPIO6 (31) (32) GPIO12
GPIO13 (33) (34) GND
GPIO19 (35) (36) GPIO16
GPIO26 (37) (38) GPIO20
   GND (39) (40) GPIO21

By default, if stdout is a console that supports color, ANSI codes will be used to produce color output. Output can be forced to be --monochrome:

$ pinout --monochrome

Or forced to be --color, in case you are redirecting to something capable of supporting ANSI codes:

$ pinout --color | less -SR

To manually specify the revision of Pi you want to query, use --revision. The tool understands both old-style revision codes (such as for the model B):

$ pinout -r 000d

Or new-style revision codes (such as for the Pi Zero W):

$ pinout -r 9000c1

You can also use the tool with Configuring Remote GPIO to query remote Raspberry Pi’s:

$ GPIOZERO_PIN_FACTORY=pigpio PIGPIO_ADDR=other_pi pinout

Or run the tool directly on a PC using the mock pin implementation (although in this case you’ll almost certainly want to specify the Pi revision manually):

$ GPIOZERO_PIN_FACTORY=mock pinout -r a22042

Environment Variables¶

GPIOZERO_PIN_FACTORY¶: The library to use when communicating with the GPIO pins. Defaults to attempting to load RPi.GPIO, then RPIO, then pigpio, and finally uses a native Python implementation. Valid values include “rpigpio”, “rpio”, “pigpio”, “native”, and “mock”. The latter is most useful on non-Pi platforms as it emulates a Raspberry Pi model 3B (by default).

PIGPIO_ADDR¶: The hostname of the Raspberry Pi the pigpio library should attempt to connect to (if the pigpio pin factory is being used). Defaults to localhost.

PIGPIO_PORT¶: The port number the pigpio library should attempt to connect to (if the pigpio pin factory is being used). Defaults to 8888.

Frequently Asked Questions¶

How do I keep my script running?¶

The following script looks like it should turn an LED on:

from gpiozero import LED

led = LED(17)
led.on()

And it does, if you’re using the Python or IPython shell, or the IDLE, Thonny or Mu editors. However, if you saved this script as a Python file and ran it, it would flash on briefly, then the script would end and it would turn off.

The following file includes an intentional pause() to keep the script alive:

from gpiozero import LED
from signal import pause

led = LED(17)
led.on()

pause()

Now the script will stay running, leaving the LED on, until it is terminated manually (e.g. by pressing Ctrl+C). Similarly, when setting up callbacks on button presses or other input devices, the script needs to be running for the events to be detected:

from gpiozero import Button
from signal import pause

def hello():
    print("Hello")

button = Button(2)
button.when_pressed = hello

pause()

What’s the difference between when_pressed, is_pressed and wait_for_press?¶

gpiozero provides a range of different approaches to reading input devices. Sometimes you want to ask if a button’s pressed, sometimes you want to do something until it’s pressed, and sometimes you want something to happen when it’s been pressed, regardless of what else is going on.

In a simple example where the button is the only device in play, all of the options would be equally effective. But as soon as you introduce an extra element, like another GPIO device, you might need to choose the right approach depending on your use case.

is_pressed is an attribute which reveals whether the button is currently pressed by returning True or False:

while True:
    if btn.is_pressed:
        print("Pressed")
    else:
        print("Not pressed")

wait_for_press() as a method which blocks the code from continuing until the button is pressed. Also see wait_for_release():

while True:
    print("Released. Waiting for press..")
    btn.wait_for_press()
    print("Pressed. Waiting for release...")
    btn.wait_for_release()

when_pressed is an attribute which assigns a callback function to the event of the button being pressed. Every time the button is pressed, the callback function is executed in a separate thread. Also see when_released:
```
def pressed():
    print("Pressed")

def released():
    print("Released")

btn.when_pressed = pressed
btn.when_released = released
```

This pattern of options is common among many devices. All input devices and internal devices have is_active, when_activated, when_deactivated, wait_for_active and wait_for_inactive, and many provide aliases (such as “pressed” for “activated”).

Also see a more advanced approach in the Source/Values page.

My event handler isn’t being called¶

When assigning event handlers, don’t call the function you’re assigning. For example:

from gpiozero import Button

def pushed():
    print("Don't push the button!")

b = Button(17)
b.when_pressed = pushed()

In the case above, when assigning to when_pressed, the thing that is assigned is the result of calling the pushed function. Because pushed doesn’t explicitly return anything, the result is None. Hence this is equivalent to doing:

b.when_pressed = None

This doesn’t raise an error because it’s perfectly valid: it’s what you assign when you don’t want the event handler to do anything. Instead, you want to do the following:

b.when_pressed = pushed

This will assign the function to the event handler without calling it. This is the crucial difference between my_function (a reference to a function) and my_function() (the result of calling a function).

Note

Note that as of v1.5, setting a callback to None when it was previously None will raise a CallbackSetToNone warning, with the intention of alerting users when callbacks are set to None accidentally. However, if this is intentional, the warning can be suppressed. See the warnings module for reference.

Why do I get PinFactoryFallback warnings when I import gpiozero?¶

You are most likely working in a virtual Python environment and have forgotten to install a pin driver library like RPi.GPIO. GPIO Zero relies upon lower level pin drivers to handle interfacing to the GPIO pins on the Raspberry Pi, so you can eliminate the warning simply by installing GPIO Zero’s first preference:

$ pip install rpi.gpio

When GPIO Zero is imported it attempts to find a pin driver by importing them in a preferred order (detailed in API - Pins). If it fails to load its first preference (RPi.GPIO) it notifies you with a warning, then falls back to trying its second preference and so on. Eventually it will fall back all the way to the native implementation. This is a pure Python implementation built into GPIO Zero itself. While this will work for most things it’s almost certainly not what you want (it doesn’t support PWM, and it’s quite slow at certain things).

If you want to use a pin driver other than the default, and you want to suppress the warnings you’ve got a couple of options:

Explicitly specify what pin driver you want via the GPIOZERO_PIN_FACTORY environment variable. For example:
```
$ GPIOZERO_PIN_FACTORY=pigpio python3
```
In this case no warning is issued because there’s no fallback; either the specified factory loads or it fails in which case an ImportError will be raised.
Suppress the warnings and let the fallback mechanism work:
```
>>> import warnings
>>> warnings.simplefilter('ignore')
>>> import gpiozero
```
Refer to the warnings module documentation for more refined ways to filter out specific warning classes.

How can I tell what version of gpiozero I have installed?¶

The gpiozero library relies on the setuptools package for installation services. You can use the setuptools pkg_resources API to query which version of gpiozero is available in your Python environment like so:

>>> from pkg_resources import require
>>> require('gpiozero')
[gpiozero 1.6.0 (/usr/lib/python3/dist-packages)]
>>> require('gpiozero')[0].version
'1.6.0'

If you have multiple versions installed (e.g. from pip and apt) they will not show up in the list returned by the pkg_resources.require() method. However, the first entry in the list will be the version that import gpiozero will import.

If you receive the error “No module named pkg_resources”, you need to install pip. This can be done with the following command in Raspberry Pi OS:

$ sudo apt install python3-pip

Alternatively, install pip with get-pip.

Why do I get “command not found” when running pinout?¶

The gpiozero library is available as a Debian package for Python 2 and Python 3, but the pinout tool cannot be made available by both packages, so it’s only included with the Python 3 version of the package. To make sure the pinout tool is available, the “python3-gpiozero” package must be installed:

$ sudo apt install python3-gpiozero

Alternatively, installing gpiozero using pip will install the command line tool, regardless of Python version:

$ sudo pip3 install gpiozero

or:

$ sudo pip install gpiozero

The pinout command line tool incorrectly identifies my Raspberry Pi model¶

If your Raspberry Pi model is new, it’s possible it wasn’t known about at the time of the gpiozero release you are using. Ensure you have the latest version installed (remember, the pinout tool usually comes from the Python 3 version of the package as noted in the previous FAQ).

If the Pi model you are using isn’t known to gpiozero, it may have been added since the last release. You can check the GitHub issues to see if it’s been reported before, or check the commits on GitHub since the last release to see if it’s been added. The model determination can be found in gpiozero/pins/data.py.

What’s the gpiozero equivalent of GPIO.cleanup()?¶

Many people ask how to do the equivalent of the cleanup function from RPi.GPIO. In gpiozero, at the end of your script, cleanup is run automatically, restoring your GPIO pins to the state they were found.

To explicitly close a connection to a pin, you can manually call the close() method on a device object:

>>> led = LED(2)
>>> led.on()
>>> led
<gpiozero.LED object on pin GPIO2, active_high=True, is_active=True>
>>> led.close()
>>> led
<gpiozero.LED object closed>

This means that you can reuse the pin for another device, and that despite turning the LED on (and hence, the pin high), after calling close() it is restored to its previous state (LED off, pin low).

Read more about Migrating from RPi.GPIO.

How do I use button.when_pressed and button.when_held together?¶

The Button class provides a when_held property which is used to set a callback for when the button is held down for a set amount of time (as determined by the hold_time property). If you want to set when_held as well as when_pressed, you’ll notice that both callbacks will fire. Sometimes, this is acceptable, but often you’ll want to only fire the when_pressed callback when the button has not been held, only pressed.

The way to achieve this is to not set a callback on when_pressed, and instead use when_released to work out whether it had been held or just pressed:

from gpiozero import Button

Button.was_held = False

def held(btn):
    btn.was_held = True
    print("button was held not just pressed")

def released(btn):
    if not btn.was_held:
        pressed()
    btn.was_held = False

def pressed():
    print("button was pressed not held")

btn = Button(2)

btn.when_held = held
btn.when_released = released

Why do I get “ImportError: cannot import name” when trying to import from gpiozero?¶

It’s common to see people name their first gpiozero script gpiozero.py. Unfortunately, this will cause your script to try to import itself, rather than the gpiozero library from the libraries path. You’ll see an error like this:

Traceback (most recent call last):
  File "gpiozero.py", line 1, in <module>
    from gpiozero import LED
  File "/home/pi/gpiozero.py", line 1, in <module>
    from gpiozero import LED
ImportError: cannot import name 'LED'

Simply rename your script to something else, and run it again. Be sure not to name any of your scripts the same name as a Python module you may be importing, such as picamera.py.

Why do I get an AttributeError trying to set attributes on a device object?¶

If you try to add an attribute to a gpiozero device object after its initialization, you’ll find you can’t:

>>> from gpiozero import Button
>>> btn = Button(2)
>>> btn.label = 'alarm'
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python3/dist-packages/gpiozero/devices.py", line 118, in __setattr__
    self.__class__.__name__, name))
AttributeError: 'Button' object has no attribute 'label'

This is in order to prevent users accidentally setting new attributes by mistake. Because gpiozero provides functionality through setting attributes via properties, such as callbacks on buttons (and often there is no immediate feedback when setting a property), this could lead to bugs very difficult to find. Consider the following example:

from gpiozero import Button

def hello():
    print("hello")

btn = Button(2)

btn.pressed = hello

This is perfectly valid Python code, and no errors would occur, but the program would not behave as expected: pressing the button would do nothing, because the property for setting a callback is when_pressed not pressed. But without gpiozero preventing this non-existent attribute from being set, the user would likely struggle to see the mistake.

If you really want to set a new attribute on a device object, you need to create it in the class before initializing your object:

>>> from gpiozero import Button
>>> Button.label = ''
>>> btn = Button(2)
>>> btn.label = 'alarm'
>>> def press(btn):
...:    print(btn.label, "was pressed")
>>> btn.when_pressed = press

Why is it called GPIO Zero? Does it only work on Pi Zero?¶

gpiozero works on all Raspberry Pi models, not just the Pi Zero.

The “zero” is part of a naming convention for “zero-boilerplate” education friendly libraries, which started with Pygame Zero, and has been followed by NetworkZero, guizero and more.

These libraries aim to remove barrier to entry and provide a smooth learning curve for beginners by making it easy to get started and easy to build up to more advanced projects.

Migrating from RPi.GPIO¶

If you are familiar with the RPi.GPIO library, you will be used to writing code which deals with pins and the state of pins. You will see from the examples in this documentation that we generally refer to things like LEDs and Buttons rather than input pins and output pins.

GPIO Zero provides classes which represent devices, so instead of having a pin number and telling it to go high, you have an LED and you tell it to turn on, and instead of having a pin number and asking if it’s high or low, you have a button and ask if it’s pressed. There is also no boilerplate code to get started — you just import the parts you need.

GPIO Zero provides many device classes, each with specific methods and properties bespoke to that device. For example, the functionality for an HC-SR04 Distance Sensor can be found in the DistanceSensor class.

As well as specific device classes, we provide base classes InputDevice and OutputDevice. One main difference between these and the equivalents in RPi.GPIO is that they are classes, not functions, which means that you initialize one to begin, and provide its pin number, but then you never need to use the pin number again, as it’s stored by the object.

GPIO Zero was originally just a layer on top of RPi.GPIO, but we later added support for various other underlying pin libraries. RPi.GPIO is currently the default pin library used. Read more about this in Changing the pin factory.

Output devices¶

Turning an LED on in RPi.GPIO:

import RPi.GPIO as GPIO

GPIO.setmode(GPIO.BCM)
GPIO.setwarnings(False)

GPIO.setup(2, GPIO.OUT)

GPIO.output(2, GPIO.HIGH)

Turning an LED on in GPIO Zero:

from gpiozero import LED

led = LED(2)

led.on()

The LED class also supports threaded blinking through the blink() method.

OutputDevice is the base class for output devices, and can be used in a similar way to output devices in RPi.GPIO.

See a full list of supported output devices. Other output devices have similar property and method names. There is commonality in naming at base level, such as OutputDevice.is_active, which is aliased in a device class, such as LED.is_lit.

Input devices¶

Reading a button press in RPi.GPIO:

import RPi.GPIO as GPIO

GPIO.setmode(GPIO.BCM)
GPIO.setwarnings(False)

GPIO.setup(4, GPIO.IN, GPIO.PUD_UP)

if not GPIO.input(4):
    print("button is pressed")

Reading a button press in GPIO Zero:

from gpiozero import Button

btn = Button(4)

if btn.is_pressed:
    print("button is pressed")

Note that in the RPi.GPIO example, the button is set up with the option GPIO.PUD_UP which means “pull-up”, and therefore when the button is not pressed, the pin is high. When the button is pressed, the pin goes low, so the condition requires negation (if not). If the button was configured as pull-down, the logic is reversed and the condition would become if GPIO.input(4):

import RPi.GPIO as GPIO

GPIO.setmode(GPIO.BCM)
GPIO.setwarnings(False)

GPIO.setup(4, GPIO.IN, GPIO.PUD_DOWN)

if GPIO.input(4):
    print("button is pressed")

In GPIO Zero, the default configuration for a button is pull-up, but this can be configured at initialization, and the rest of the code stays the same:

from gpiozero import Button

btn = Button(4, pull_up=False)

if btn.is_pressed:
    print("button is pressed")

RPi.GPIO also supports blocking edge detection.

Wait for a pull-up button to be pressed in RPi.GPIO:

import RPi.GPIO as GPIO

GPIO.setmode(GPIO.BCM)
GPIO.setwarnings(False)

GPIO.setup(4, GPIO.IN, GPIO.PUD_UP)

GPIO.wait_for_edge(4, GPIO.FALLING):
print("button was pressed")

The equivalent in GPIO Zero:

from gpiozero import Buttons

btn = Button(4)

btn.wait_for_press()
print("button was pressed")

Again, if the button is pulled down, the logic is reversed. Instead of waiting for a falling edge, we’re waiting for a rising edge:

import RPi.GPIO as GPIO

GPIO.setmode(GPIO.BCM)
GPIO.setwarnings(False)

GPIO.setup(4, GPIO.IN, GPIO.PUD_UP)

GPIO.wait_for_edge(4, GPIO.FALLING):
print("button was pressed")

Again, in GPIO Zero, the only difference is in the initialization:

from gpiozero import Buttons

btn = Button(4, pull_up=False)

btn.wait_for_press()
print("button was pressed")

RPi.GPIO has threaded callbacks. You create a function (which must take one argument), and pass it in to add_event_detect, along with the pin number and the edge direction:

import RPi.GPIO as GPIO

GPIO.setmode(GPIO.BCM)
GPIO.setwarnings(False)

def pressed(pin):
    print("button was pressed")

def released(pin):
    print("button was released")

GPIO.setup(4, GPIO.IN, GPIO.PUD_UP)

GPIO.add_event_detect(4, GPIO.FALLING, pressed)
GPIO.add_event_detect(4, GPIO.RISING, released)

In GPIO Zero, you assign the when_pressed and when_released properties to set up callbacks on those actions:

from gpiozero import Buttons

def pressed():
    print("button was pressed")

def released():
    print("button was released")

btn = Button(4)

btn.when_pressed = pressed
btn.when_released = released

when_held is also provided, where the length of time considered a “hold” is configurable.

The callback functions don’t have to take any arguments, but if they take one, the button object is passed in, allowing you to determine which button called the function.

InputDevice is the base class for input devices, and can be used in a similar way to input devices in RPi.GPIO.

See a full list of input devices. Other input devices have similar property and method names. There is commonality in naming at base level, such as InputDevice.is_active, which is aliased in a device class, such as Button.is_pressed and LightSensor.light_detected.

Composite devices, boards and accessories¶

Some devices require connections to multiple pins, for example a distance sensor, a combination of LEDs or a HAT. Some GPIO Zero devices comprise multiple device connections within one object, such as RGBLED, LEDBoard, DistanceSensor, Motor and Robot.

With RPi.GPIO, you would have one output pin for the trigger, and one input pin for the echo. You would time the echo and calculate the distance. With GPIO Zero, you create a single DistanceSensor object, specifying the trigger and echo pins, and you would read the DistanceSensor.distance property which automatically calculates the distance within the implementation of the class.

The Motor class controls two output pins to drive the motor forwards or backwards. The Robot class controls four output pins (two motors) in the right combination to drive a robot forwards or backwards, and turn left and right.

The LEDBoard class takes an arbitrary number of pins, each controlling a single LED. The resulting LEDBoard object can be used to control all LEDs together (all on / all off), or individually by index. Also the object can be iterated over to turn LEDs on in order. See examples of this (including slicing) in the advanced recipes.

PWM (Pulse-width modulation)¶

Both libraries support software PWM control on any pin. Depending on the pin library used, GPIO Zero can also support hardware PWM (using RPIOPin or PiGPIOPin).

A simple example of using PWM is to control the brightness of an LED.

In RPi.GPIO:

import RPi.GPIO as GPIO
from time import sleep

GPIO.setmode(GPIO.BCM)
GPIO.setwarnings(False)

GPIO.setup(2, GPIO.OUT)
pwm = GPIO.PWM(2, 100)
pwm.start(0)

for dc in range(101):
    pwm.changeDutyCycle(dc)
    sleep(0.01)

In GPIO Zero:

from gpiozero import PWMLED
from time import sleep

led = PWMLED(2)

for b in range(101):
    led.value = b / 100.0
    sleep(0.01)

PWMLED has a blink() method which can be used the same was as LED’s blink() method, but its PWM capabilities allow for fade_in and fade_out options to be provided. There is also the pulse() method which provides a neat way to have an LED fade in and out repeatedly.

Other devices can make use of PWM, such as motors (for variable speed) and servos. See the Motor, Servo and AngularServo classes for information on those. Motor and Robot default to using PWM, but it can be disabled with pwm=False at initialization. Servos cannot be used without PWM. Devices containing LEDs default to not using PWM, but pwm=True can be specified and any LED objects within the device will be initialized as PWMLED objects.

Cleanup¶

Pin state cleanup is explicit in RPi.GPIO, and is done manually with GPIO.cleanup() but in GPIO Zero, cleanup is automatically performed on every pin used, at the end of the script. Manual cleanup is possible by use of the close() method on the device.

Note that cleanup only occurs at the point of normal termination of the script. If the script exits due to a program error, cleanup will not be performed. To ensure that cleanup is performed after an exception is raised, the exception must be handled, for example:

from gpiozero import Button

btn = Button(4)

while True:
    try:
        if btn.is_pressed:
            print("Pressed")
    except KeyboardInterrupt:
        print("Ending program")

Read more in the relevant FAQ: What’s the gpiozero equivalent of GPIO.cleanup()?

Pi Information¶

RPi.GPIO provides information about the Pi you’re using. The equivalent in GPIO Zero is the function pi_info():

>>> from gpiozero import pi_info
>>> pi = pi_info()
>>> pi
PiBoardInfo(revision='a02082', model='3B', pcb_revision='1.2', released='2016Q1', soc='BCM2837', manufacturer='Sony', memory=1024, storage='MicroSD', usb=4, ethernet=1, wifi=True, bluetooth=True, csi=1, dsi=1, headers=..., board=...)
>>> pi.soc
'BCM2837'
>>> pi.wifi
True

Read more about what PiBoardInfo provides.

More¶

GPIO Zero provides more than just GPIO device support, it includes some support for SPI devices including a range of analog to digital converters.

Device classes which are compatible with other GPIO devices, but have no relation to GPIO pins, such as CPUTemperature, TimeOfDay, PingServer and LoadAverage are also provided.

GPIO Zero features support for multiple pin libraries. The default is to use RPi.GPIO to control the pins, but you can choose to use another library, such as pigpio, which supports network controlled GPIO. See Changing the pin factory and Configuring Remote GPIO for more information.

It is possible to run GPIO Zero on your PC, both for remote GPIO and for testing purposes, using Mock pins.

Another feature of this library is configuring devices to be connected together in a logical way, for example in one line you can say that an LED and button are “paired”, i.e. the button being pressed turns the LED on. Read about this in Source/Values.

FAQs¶

Note the following FAQs which may catch out users too familiar with RPi.GPIO:

Contributing¶

Contributions to the library are welcome! Here are some guidelines to follow.

Suggestions¶

Please make suggestions for additional components or enhancements to the codebase by opening an issue explaining your reasoning clearly.

Bugs¶

Please submit bug reports by opening an issue explaining the problem clearly using code examples.

Documentation¶

The documentation source lives in the docs folder. Contributions to the documentation are welcome but should be easy to read and understand.

Commit messages and pull requests¶

Commit messages should be concise but descriptive, and in the form of a patch description, i.e. instructional not past tense (“Add LED example” not “Added LED example”).

Commits which close (or intend to close) an issue should include the phrase “fix #123” or “close #123” where #123 is the issue number, as well as include a short description, for example: “Add LED example, close #123”, and pull requests should aim to match or closely match the corresponding issue title.

Copyrights on submissions are owned by their authors (we don’t bother with copyright assignments), and we assume that authors are happy for their code to be released under the project’s license. Do feel free to add your name to the list of contributors in README.rst at the top level of the project in your pull request! Don’t worry about adding your name to the copyright headers in whatever files you touch; these are updated automatically from the git metadata before each release.

Backwards compatibility¶

Since this library reached v1.0 we aim to maintain backwards-compatibility thereafter. Changes which break backwards-compatibility will not be accepted.

Python 2/3¶

The library is 100% compatible with both Python 2.7 and Python 3 from version 3.2 onwards. Since Python 2 is now past its end-of-life, the 1.6.0 release (2021-03-14) is the last to support Python 2.

Development¶

The main GitHub repository for the project can be found at:

https://github.com/gpiozero/gpiozero

For anybody wishing to hack on the project, we recommend starting off by getting to grips with some simple device classes. Pick something like LED and follow its heritage backward to DigitalOutputDevice. Follow that back to OutputDevice and you should have a good understanding of simple output devices along with a grasp of how GPIO Zero relies fairly heavily upon inheritance to refine the functionality of devices. The same can be done for input devices, and eventually more complex devices (composites and SPI based).

Development installation¶

If you wish to develop GPIO Zero itself, we recommend obtaining the source by cloning the GitHub repository and then use the “develop” target of the Makefile which will install the package as a link to the cloned repository allowing in-place development (it also builds a tags file for use with vim/emacs with Exuberant’s ctags utility). The following example demonstrates this method within a virtual Python environment:

$ sudo apt install lsb-release build-essential git exuberant-ctags \
    virtualenvwrapper python-virtualenv python3-virtualenv \
    python-dev python3-dev

After installing virtualenvwrapper you’ll need to restart your shell before commands like mkvirtualenv will operate correctly. Once you’ve restarted your shell, continue:

$ cd
$ mkvirtualenv -p /usr/bin/python3 gpiozero
$ workon gpiozero
(gpiozero) $ git clone https://github.com/gpiozero/gpiozero.git
(gpiozero) $ cd gpiozero
(gpiozero) $ make develop

You will likely wish to install one or more pin implementations within the virtual environment (if you don’t, GPIO Zero will use the “native” pin implementation which is usable at this stage, but doesn’t support facilities like PWM):

(gpiozero) $ pip install rpi.gpio pigpio

If you are working on SPI devices you may also wish to install the spidev package to provide hardware SPI capabilities (again, GPIO Zero will work without this, but a big-banging software SPI implementation will be used instead which limits bandwidth):

(gpiozero) $ pip install spidev

To pull the latest changes from git into your clone and update your installation:

$ workon gpiozero
(gpiozero) $ cd ~/gpiozero
(gpiozero) $ git pull
(gpiozero) $ make develop

To remove your installation, destroy the sandbox and the clone:

(gpiozero) $ deactivate
$ rmvirtualenv gpiozero
$ rm -rf ~/gpiozero

Building the docs¶

If you wish to build the docs, you’ll need a few more dependencies. Inkscape is used for conversion of SVGs to other formats, Graphviz is used for rendering certain charts, and TeX Live is required for building PDF output. The following command should install all required dependencies:

$ sudo apt install texlive-latex-recommended texlive-latex-extra \
    texlive-fonts-recommended texlive-xetex graphviz inkscape \
    python3-sphinx python3-sphinx-rtd-theme latexmk xindy

Once these are installed, you can use the “doc” target to build the documentation:

$ workon gpiozero
(gpiozero) $ cd ~/gpiozero
(gpiozero) $ make doc

The HTML output is written to build/html while the PDF output goes to build/latex.

Test suite¶

If you wish to run the GPIO Zero test suite, follow the instructions in Development installation above and then make the “test” target within the sandbox. You’ll also need to install some pip packages:

$ workon gpiozero
(gpiozero) $ pip install coverage mock pytest
(gpiozero) $ cd ~/gpiozero
(gpiozero) $ make test

The test suite expects pins 22 and 27 (by default) to be wired together in order to run the “real” pin tests. The pins used by the test suite can be overridden with the environment variables GPIOZERO_TEST_PIN (defaults to 22) and GPIOZERO_TEST_INPUT_PIN (defaults to 27).

Warning

When wiring GPIOs together, ensure a load (like a 1KΩ resistor) is placed between them. Failure to do so may lead to blown GPIO pins (your humble author has a fried GPIO27 as a result of such laziness, although it did take many runs of the test suite before this occurred!).

The test suite is also setup for usage with the tox utility, in which case it will attempt to execute the test suite with all supported versions of Python. If you are developing under Ubuntu you may wish to look into the Dead Snakes PPA in order to install old/new versions of Python; the tox setup should work with the version of tox shipped with Ubuntu Xenial, but more features (like parallel test execution) are available with later versions.

On the subject of parallel test execution, this is also supported in the tox setup, including the “real” pin tests (a file-system level lock is used to ensure different interpreters don’t try to access the physical pins simultaneously).

For example, to execute the test suite under tox, skipping interpreter versions which are not installed:

$ tox -s

To execute the test suite under all installed interpreter versions in parallel, using as many parallel tasks as there are CPUs, then displaying a combined report of coverage from all environments:

$ tox -p auto -s
$ coverage combine --rcfile coverage.cfg
$ coverage report --rcfile coverage.cfg

Mock pins¶

The test suite largely depends on the existence of the mock pin factory MockFactory, which is also useful for manual testing, for example in the Python shell or another REPL. See the section on Mock pins in the API - Pins chapter for more information.

API - Input Devices¶

These input device component interfaces have been provided for simple use of everyday components. Components must be wired up correctly before use in code.

Note

All GPIO pin numbers use Broadcom (BCM) numbering by default. See the Pin Numbering section for more information.

Regular Classes¶

The following classes are intended for general use with the devices they represent. All classes in this section are concrete (not abstract).

Button¶

class gpiozero.Button(pin, *, pull_up=True, active_state=None, bounce_time=None, hold_time=1, hold_repeat=False, pin_factory=None)[source]¶

Extends DigitalInputDevice and represents a simple push button or switch.

Connect one side of the button to a ground pin, and the other to any GPIO pin. Alternatively, connect one side of the button to the 3V3 pin, and the other to any GPIO pin, then set pull_up to False in the Button constructor.

The following example will print a line of text when the button is pushed:

from gpiozero import Button

button = Button(4)
button.wait_for_press()
print("The button was pressed!")

Parameters:

pin (int or str) – The GPIO pin which the button is connected to. See Pin Numbering for valid pin numbers. If this is None a GPIODeviceError will be raised.
pull_up (bool or None) – If True (the default), the GPIO pin will be pulled high by default. In this case, connect the other side of the button to ground. If False, the GPIO pin will be pulled low by default. In this case, connect the other side of the button to 3V3. If None, the pin will be floating, so it must be externally pulled up or down and the active_state parameter must be set accordingly.
active_state (bool or None) – See description under InputDevice for more information.
bounce_time (float or None) – If None (the default), no software bounce compensation will be performed. Otherwise, this is the length of time (in seconds) that the component will ignore changes in state after an initial change.
hold_time (float) – The length of time (in seconds) to wait after the button is pushed, until executing the when_held handler. Defaults to 1.
hold_repeat (bool) – If True, the when_held handler will be repeatedly executed as long as the device remains active, every hold_time seconds. If False (the default) the when_held handler will be only be executed once per hold.
pin_factory (Factory or None) – See API - Pins for more information (this is an advanced feature which most users can ignore).

wait_for_press(timeout=None)¶

Pause the script until the device is activated, or the timeout is reached.

Parameters:	timeout (float or None) – Number of seconds to wait before proceeding. If this is `None` (the default), then wait indefinitely until the device is active.

wait_for_release(timeout=None)¶

Pause the script until the device is deactivated, or the timeout is reached.

Parameters:	timeout (float or None) – Number of seconds to wait before proceeding. If this is `None` (the default), then wait indefinitely until the device is inactive.

held_time¶: The length of time (in seconds) that the device has been held for. This is counted from the first execution of the when_held event rather than when the device activated, in contrast to active_time. If the device is not currently held, this is None.

hold_repeat¶: If True, when_held will be executed repeatedly with hold_time seconds between each invocation.

hold_time¶: The length of time (in seconds) to wait after the device is activated, until executing the when_held handler. If hold_repeat is True, this is also the length of time between invocations of when_held.

is_held¶: When True, the device has been active for at least hold_time seconds.

is_pressed¶: Returns True if the device is currently active and False otherwise. This property is usually derived from value. Unlike value, this is always a boolean.

pin¶: The Pin that the device is connected to. This will be None if the device has been closed (see the close() method). When dealing with GPIO pins, query pin.number to discover the GPIO pin (in BCM numbering) that the device is connected to.

pull_up¶: If True, the device uses a pull-up resistor to set the GPIO pin “high” by default.

value¶: Returns 1 if the button is currently pressed, and 0 if it is not.

when_held¶

The function to run when the device has remained active for hold_time seconds.

This can be set to a function which accepts no (mandatory) parameters, or a Python function which accepts a single mandatory parameter (with as many optional parameters as you like). If the function accepts a single mandatory parameter, the device that activated will be passed as that parameter.

Set this property to None (the default) to disable the event.

when_pressed¶

The function to run when the device changes state from inactive to active.

This can be set to a function which accepts no (mandatory) parameters, or a Python function which accepts a single mandatory parameter (with as many optional parameters as you like). If the function accepts a single mandatory parameter, the device that activated it will be passed as that parameter.

Set this property to None (the default) to disable the event.

when_released¶

The function to run when the device changes state from active to inactive.

This can be set to a function which accepts no (mandatory) parameters, or a Python function which accepts a single mandatory parameter (with as many optional parameters as you like). If the function accepts a single mandatory parameter, the device that deactivated it will be passed as that parameter.

Set this property to None (the default) to disable the event.

LineSensor (TRCT5000)¶

class gpiozero.LineSensor(pin, *, queue_len=5, sample_rate=100, threshold=0.5, partial=False, pin_factory=None)[source]¶

Extends SmoothedInputDevice and represents a single pin line sensor like the TCRT5000 infra-red proximity sensor found in the CamJam #3 EduKit.

A typical line sensor has a small circuit board with three pins: VCC, GND, and OUT. VCC should be connected to a 3V3 pin, GND to one of the ground pins, and finally OUT to the GPIO specified as the value of the pin parameter in the constructor.

The following code will print a line of text indicating when the sensor detects a line, or stops detecting a line:

from gpiozero import LineSensor
from signal import pause

sensor = LineSensor(4)
sensor.when_line = lambda: print('Line detected')
sensor.when_no_line = lambda: print('No line detected')
pause()

Parameters:

pin (int or str) – The GPIO pin which the sensor is connected to. See Pin Numbering for valid pin numbers. If this is None a GPIODeviceError will be raised.
pull_up (bool or None) – See description under InputDevice for more information.
active_state (bool or None) – See description under InputDevice for more information.
queue_len (int) – The length of the queue used to store values read from the sensor. This defaults to 5.
sample_rate (float) – The number of values to read from the device (and append to the internal queue) per second. Defaults to 100.
threshold (float) – Defaults to 0.5. When the average of all values in the internal queue rises above this value, the sensor will be considered “active” by the is_active property, and all appropriate events will be fired.
partial (bool) – When False (the default), the object will not return a value for is_active until the internal queue has filled with values. Only set this to True if you require values immediately after object construction.
pin_factory (Factory or None) – See API - Pins for more information (this is an advanced feature which most users can ignore).

wait_for_line(timeout=None)¶

Pause the script until the device is deactivated, or the timeout is reached.

Parameters:	timeout (float or None) – Number of seconds to wait before proceeding. If this is `None` (the default), then wait indefinitely until the device is inactive.

wait_for_no_line(timeout=None)¶

Pause the script until the device is activated, or the timeout is reached.

Parameters:	timeout (float or None) – Number of seconds to wait before proceeding. If this is `None` (the default), then wait indefinitely until the device is active.

pin¶: The Pin that the device is connected to. This will be None if the device has been closed (see the close() method). When dealing with GPIO pins, query pin.number to discover the GPIO pin (in BCM numbering) that the device is connected to.

value¶: Returns a value representing the average of the queued values. This is nearer 0 for black under the sensor, and nearer 1 for white under the sensor.

when_line¶

The function to run when the device changes state from active to inactive.

This can be set to a function which accepts no (mandatory) parameters, or a Python function which accepts a single mandatory parameter (with as many optional parameters as you like). If the function accepts a single mandatory parameter, the device that deactivated it will be passed as that parameter.

Set this property to None (the default) to disable the event.

when_no_line¶

The function to run when the device changes state from inactive to active.

This can be set to a function which accepts no (mandatory) parameters, or a Python function which accepts a single mandatory parameter (with as many optional parameters as you like). If the function accepts a single mandatory parameter, the device that activated it will be passed as that parameter.

Set this property to None (the default) to disable the event.

MotionSensor (D-SUN PIR)¶

class gpiozero.MotionSensor(pin, *, queue_len=1, sample_rate=10, threshold=0.5, partial=False, pin_factory=None)[source]¶

Extends SmoothedInputDevice and represents a passive infra-red (PIR) motion sensor like the sort found in the CamJam #2 EduKit.

A typical PIR device has a small circuit board with three pins: VCC, OUT, and GND. VCC should be connected to a 5V pin, GND to one of the ground pins, and finally OUT to the GPIO specified as the value of the pin parameter in the constructor.

The following code will print a line of text when motion is detected:

from gpiozero import MotionSensor

pir = MotionSensor(4)
pir.wait_for_motion()
print("Motion detected!")

Parameters:

pin (int or str) – The GPIO pin which the sensor is connected to. See Pin Numbering for valid pin numbers. If this is None a GPIODeviceError will be raised.
pull_up (bool or None) – See description under InputDevice for more information.
active_state (bool or None) – See description under InputDevice for more information.
queue_len (int) – The length of the queue used to store values read from the sensor. This defaults to 1 which effectively disables the queue. If your motion sensor is particularly “twitchy” you may wish to increase this value.
sample_rate (float) – The number of values to read from the device (and append to the internal queue) per second. Defaults to 10.
threshold (float) – Defaults to 0.5. When the average of all values in the internal queue rises above this value, the sensor will be considered “active” by the is_active property, and all appropriate events will be fired.
partial (bool) – When False (the default), the object will not return a value for is_active until the internal queue has filled with values. Only set this to True if you require values immediately after object construction.
pin_factory (Factory or None) – See API - Pins for more information (this is an advanced feature which most users can ignore).

wait_for_motion(timeout=None)¶

Pause the script until the device is activated, or the timeout is reached.

Parameters:	timeout (float or None) – Number of seconds to wait before proceeding. If this is `None` (the default), then wait indefinitely until the device is active.

wait_for_no_motion(timeout=None)¶

Pause the script until the device is deactivated, or the timeout is reached.

Parameters:	timeout (float or None) – Number of seconds to wait before proceeding. If this is `None` (the default), then wait indefinitely until the device is inactive.

motion_detected¶: Returns True if the value currently exceeds threshold and False otherwise.

pin¶: The Pin that the device is connected to. This will be None if the device has been closed (see the close() method). When dealing with GPIO pins, query pin.number to discover the GPIO pin (in BCM numbering) that the device is connected to.

value¶: With the default queue_len of 1, this is effectively boolean where 0 means no motion detected and 1 means motion detected. If you specify a queue_len greater than 1, this will be an averaged value where values closer to 1 imply motion detection.

when_motion¶

The function to run when the device changes state from inactive to active.

This can be set to a function which accepts no (mandatory) parameters, or a Python function which accepts a single mandatory parameter (with as many optional parameters as you like). If the function accepts a single mandatory parameter, the device that activated it will be passed as that parameter.

Set this property to None (the default) to disable the event.

when_no_motion¶

The function to run when the device changes state from active to inactive.

This can be set to a function which accepts no (mandatory) parameters, or a Python function which accepts a single mandatory parameter (with as many optional parameters as you like). If the function accepts a single mandatory parameter, the device that deactivated it will be passed as that parameter.

Set this property to None (the default) to disable the event.

LightSensor (LDR)¶

class gpiozero.LightSensor(pin, *, queue_len=5, charge_time_limit=0.01, threshold=0.1, partial=False, pin_factory=None)[source]¶

Extends SmoothedInputDevice and represents a light dependent resistor (LDR).

Connect one leg of the LDR to the 3V3 pin; connect one leg of a 1µF capacitor to a ground pin; connect the other leg of the LDR and the other leg of the capacitor to the same GPIO pin. This class repeatedly discharges the capacitor, then times the duration it takes to charge (which will vary according to the light falling on the LDR).

The following code will print a line of text when light is detected:

from gpiozero import LightSensor

ldr = LightSensor(18)
ldr.wait_for_light()
print("Light detected!")

Parameters:

pin (int or str) – The GPIO pin which the sensor is attached to. See Pin Numbering for valid pin numbers. If this is None a GPIODeviceError will be raised.
queue_len (int) – The length of the queue used to store values read from the circuit. This defaults to 5.
charge_time_limit (float) – If the capacitor in the circuit takes longer than this length of time to charge, it is assumed to be dark. The default (0.01 seconds) is appropriate for a 1µF capacitor coupled with the LDR from the CamJam #2 EduKit. You may need to adjust this value for different valued capacitors or LDRs.
threshold (float) – Defaults to 0.1. When the average of all values in the internal queue rises above this value, the area will be considered “light”, and all appropriate events will be fired.
partial (bool) – When False (the default), the object will not return a value for is_active until the internal queue has filled with values. Only set this to True if you require values immediately after object construction.
pin_factory (Factory or None) – See API - Pins for more information (this is an advanced feature which most users can ignore).

wait_for_dark(timeout=None)¶

Pause the script until the device is deactivated, or the timeout is reached.

Parameters:	timeout (float or None) – Number of seconds to wait before proceeding. If this is `None` (the default), then wait indefinitely until the device is inactive.

wait_for_light(timeout=None)¶

Pause the script until the device is activated, or the timeout is reached.

Parameters:	timeout (float or None) – Number of seconds to wait before proceeding. If this is `None` (the default), then wait indefinitely until the device is active.

light_detected¶: Returns True if the value currently exceeds threshold and False otherwise.

pin¶: The Pin that the device is connected to. This will be None if the device has been closed (see the close() method). When dealing with GPIO pins, query pin.number to discover the GPIO pin (in BCM numbering) that the device is connected to.

value¶: Returns a value between 0 (dark) and 1 (light).

when_dark¶

The function to run when the device changes state from active to inactive.

This can be set to a function which accepts no (mandatory) parameters, or a Python function which accepts a single mandatory parameter (with as many optional parameters as you like). If the function accepts a single mandatory parameter, the device that deactivated it will be passed as that parameter.

Set this property to None (the default) to disable the event.

when_light¶

The function to run when the device changes state from inactive to active.

This can be set to a function which accepts no (mandatory) parameters, or a Python function which accepts a single mandatory parameter (with as many optional parameters as you like). If the function accepts a single mandatory parameter, the device that activated it will be passed as that parameter.

Set this property to None (the default) to disable the event.

DistanceSensor (HC-SR04)¶

class gpiozero.DistanceSensor(echo, trigger, *, queue_len=30, max_distance=1, threshold_distance=0.3, partial=False, pin_factory=None)[source]¶

Extends SmoothedInputDevice and represents an HC-SR04 ultrasonic distance sensor, as found in the CamJam #3 EduKit.

The distance sensor requires two GPIO pins: one for the trigger (marked TRIG on the sensor) and another for the echo (marked ECHO on the sensor). However, a voltage divider is required to ensure the 5V from the ECHO pin doesn’t damage the Pi. Wire your sensor according to the following instructions:

Connect the GND pin of the sensor to a ground pin on the Pi.
Connect the TRIG pin of the sensor a GPIO pin.
Connect one end of a 330Ω resistor to the ECHO pin of the sensor.
Connect one end of a 470Ω resistor to the GND pin of the sensor.
Connect the free ends of both resistors to another GPIO pin. This forms the required voltage divider.
Finally, connect the VCC pin of the sensor to a 5V pin on the Pi.

Alternatively, the 3V3 tolerant HC-SR04P sensor (which does not require a voltage divider) will work with this class.

Note

If you do not have the precise values of resistor specified above, don’t worry! What matters is the ratio of the resistors to each other.

You also don’t need to be absolutely precise; the voltage divider given above will actually output ~3V (rather than 3.3V). A simple 2:3 ratio will give 3.333V which implies you can take three resistors of equal value, use one of them instead of the 330Ω resistor, and two of them in series instead of the 470Ω resistor.

The following code will periodically report the distance measured by the sensor in cm assuming the TRIG pin is connected to GPIO17, and the ECHO pin to GPIO18:

from gpiozero import DistanceSensor
from time import sleep

sensor = DistanceSensor(echo=18, trigger=17)
while True:
    print('Distance: ', sensor.distance * 100)
    sleep(1)

Note

For improved accuracy, use the pigpio pin driver rather than the default RPi.GPIO driver (pigpio uses DMA sampling for much more precise edge timing). This is particularly relevant if you’re using Pi 1 or Pi Zero. See Changing the pin factory for further information.

Parameters:

echo (int or str) – The GPIO pin which the ECHO pin is connected to. See Pin Numbering for valid pin numbers. If this is None a GPIODeviceError will be raised.
trigger (int or str) – The GPIO pin which the TRIG pin is connected to. See Pin Numbering for valid pin numbers. If this is None a GPIODeviceError will be raised.
queue_len (int) – The length of the queue used to store values read from the sensor. This defaults to 9.
max_distance (float) – The value attribute reports a normalized value between 0 (too close to measure) and 1 (maximum distance). This parameter specifies the maximum distance expected in meters. This defaults to 1.
threshold_distance (float) – Defaults to 0.3. This is the distance (in meters) that will trigger the in_range and out_of_range events when crossed.
partial (bool) – When False (the default), the object will not return a value for is_active until the internal queue has filled with values. Only set this to True if you require values immediately after object construction.
pin_factory (Factory or None) – See API - Pins for more information (this is an advanced feature which most users can ignore).

wait_for_in_range(timeout=None)¶

Pause the script until the device is deactivated, or the timeout is reached.

Parameters:	timeout (float or None) – Number of seconds to wait before proceeding. If this is `None` (the default), then wait indefinitely until the device is inactive.

wait_for_out_of_range(timeout=None)¶

Pause the script until the device is activated, or the timeout is reached.

Parameters:	timeout (float or None) – Number of seconds to wait before proceeding. If this is `None` (the default), then wait indefinitely until the device is active.

distance¶: Returns the current distance measured by the sensor in meters. Note that this property will have a value between 0 and max_distance.

echo¶: Returns the Pin that the sensor’s echo is connected to. This is simply an alias for the usual pin attribute.

max_distance¶: The maximum distance that the sensor will measure in meters. This value is specified in the constructor and is used to provide the scaling for the value attribute. When distance is equal to max_distance, value will be 1.

threshold_distance¶: The distance, measured in meters, that will trigger the when_in_range and when_out_of_range events when crossed. This is simply a meter-scaled variant of the usual threshold attribute.

trigger¶: Returns the Pin that the sensor’s trigger is connected to.

value¶: Returns a value between 0, indicating the reflector is either touching the sensor or is sufficiently near that the sensor can’t tell the difference, and 1, indicating the reflector is at or beyond the specified max_distance.

when_in_range¶

The function to run when the device changes state from active to inactive.

This can be set to a function which accepts no (mandatory) parameters, or a Python function which accepts a single mandatory parameter (with as many optional parameters as you like). If the function accepts a single mandatory parameter, the device that deactivated it will be passed as that parameter.

Set this property to None (the default) to disable the event.

when_out_of_range¶

The function to run when the device changes state from inactive to active.

This can be set to a function which accepts no (mandatory) parameters, or a Python function which accepts a single mandatory parameter (with as many optional parameters as you like). If the function accepts a single mandatory parameter, the device that activated it will be passed as that parameter.

Set this property to None (the default) to disable the event.

RotaryEncoder¶

class gpiozero.RotaryEncoder(a, b, *, bounce_time=None, max_steps=16, threshold_steps=(0, 0), wrap=False, pin_factory=None)[source]¶

Represents a simple two-pin incremental rotary encoder device.

These devices typically have three pins labelled “A”, “B”, and “C”. Connect A and B directly to two GPIO pins, and C (“common”) to one of the ground pins on your Pi. Then simply specify the A and B pins as the arguments when constructing this classs.

For example, if your encoder’s A pin is connected to GPIO 21, and the B pin to GPIO 20 (and presumably the C pin to a suitable GND pin), while an LED (with a suitable 300Ω resistor) is connected to GPIO 5, the following session will result in the brightness of the LED being controlled by dialling the rotary encoder back and forth:

>>> from gpiozero import RotaryEncoder
>>> from gpiozero.tools import scaled_half
>>> rotor = RotaryEncoder(21, 20)
>>> led = PWMLED(5)
>>> led.source = scaled_half(rotor.values)

Parameters:

a (int or str) – The GPIO pin connected to the “A” output of the rotary encoder.
b (int or str) – The GPIO pin connected to the “B” output of the rotary encoder.
bounce_time (float or None) – If None (the default), no software bounce compensation will be performed. Otherwise, this is the length of time (in seconds) that the component will ignore changes in state after an initial change.
max_steps (int) – The number of steps clockwise the encoder takes to change the value from 0 to 1, or counter-clockwise from 0 to -1. If this is 0, then the encoder’s value never changes, but you can still read steps to determine the integer number of steps the encoder has moved clockwise or counter clockwise.
threshold_steps (tuple of int) – A (min, max) tuple of steps between which the device will be considered “active”, inclusive. In other words, when steps is greater than or equal to the min value, and less than or equal the max value, the active property will be True and the appropriate events (when_activated, when_deactivated) will be fired. Defaults to (0, 0).
wrap (bool) – If True and max_steps is non-zero, when the steps reaches positive or negative max_steps it wraps around by negation. Defaults to False.
pin_factory (Factory or None) – See API - Pins for more information (this is an advanced feature which most users can ignore).

wait_for_rotate(timeout=None)[source]¶

Pause the script until the encoder is rotated at least one step in either direction, or the timeout is reached.

Parameters:	timeout (float or None) – Number of seconds to wait before proceeding. If this is `None` (the default), then wait indefinitely until the encoder is rotated.

wait_for_rotate_clockwise(timeout=None)[source]¶

Pause the script until the encoder is rotated at least one step clockwise, or the timeout is reached.

Parameters:	timeout (float or None) – Number of seconds to wait before proceeding. If this is `None` (the default), then wait indefinitely until the encoder is rotated clockwise.

wait_for_rotate_counter_clockwise(timeout=None)[source]¶

Pause the script until the encoder is rotated at least one step counter-clockwise, or the timeout is reached.

Parameters:	timeout (float or None) – Number of seconds to wait before proceeding. If this is `None` (the default), then wait indefinitely until the encoder is rotated counter-clockwise.

max_steps¶: The number of discrete steps the rotary encoder takes to move value from 0 to 1 clockwise, or 0 to -1 counter-clockwise. In another sense, this is also the total number of discrete states this input can represent.

steps¶

The “steps” value of the encoder starts at 0. It increments by one for every step the encoder is rotated clockwise, and decrements by one for every step it is rotated counter-clockwise. The steps value is limited by max_steps. It will not advance beyond positive or negative max_steps, unless wrap is True in which case it will roll around by negation. If max_steps is zero then steps are not limited at all, and will increase infinitely in either direction, but value will return a constant zero.

Note that, in contrast to most other input devices, because the rotary encoder has no absolute position the steps attribute (and value by corollary) is writable.

threshold_steps¶: The mininum and maximum number of steps between which is_active will return True. Defaults to (0, 0).

value¶

Represents the value of the rotary encoder as a value between -1 and 1. The value is calculated by dividing the value of steps into the range from negative max_steps to positive max_steps.

Note that, in contrast to most other input devices, because the rotary encoder has no absolute position the value attribute is writable.

when_rotated¶

The function to be run when the encoder is rotated in either direction.

This can be set to a function which accepts no (mandatory) parameters, or a Python function which accepts a single mandatory parameter (with as many optional parameters as you like). If the function accepts a single mandatory parameter, the device that activated will be passed as that parameter.

Set this property to None (the default) to disable the event.

when_rotated_clockwise¶

The function to be run when the encoder is rotated clockwise.

This can be set to a function which accepts no (mandatory) parameters, or a Python function which accepts a single mandatory parameter (with as many optional parameters as you like). If the function accepts a single mandatory parameter, the device that activated will be passed as that parameter.

Set this property to None (the default) to disable the event.

when_rotated_counter_clockwise¶

The function to be run when the encoder is rotated counter-clockwise.

This can be set to a function which accepts no (mandatory) parameters, or a Python function which accepts a single mandatory parameter (with as many optional parameters as you like). If the function accepts a single mandatory parameter, the device that activated will be passed as that parameter.

Set this property to None (the default) to disable the event.

wrap¶: If True, when value reaches its limit (-1 or 1), it “wraps around” to the opposite limit. When False, the value (and the corresponding steps attribute) simply don’t advance beyond their limits.

Base Classes¶

The classes in the sections above are derived from a series of base classes, some of which are effectively abstract. The classes form the (partial) hierarchy displayed in the graph below (abstract classes are shaded lighter than concrete classes):

The following sections document these base classes for advanced users that wish to construct classes for their own devices.

DigitalInputDevice¶

class gpiozero.DigitalInputDevice(pin, *, pull_up=False, active_state=None, bounce_time=None, pin_factory=None)[source]¶

Represents a generic input device with typical on/off behaviour.

This class extends InputDevice with machinery to fire the active and inactive events for devices that operate in a typical digital manner: straight forward on / off states with (reasonably) clean transitions between the two.

Parameters:

pin (int or str) – The GPIO pin that the device is connected to. See Pin Numbering for valid pin numbers. If this is None a GPIODeviceError will be raised.
pull_up (bool or None) – See description under InputDevice for more information.
active_state (bool or None) – See description under InputDevice for more information.
bounce_time (float or None) – Specifies the length of time (in seconds) that the component will ignore changes in state after an initial change. This defaults to None which indicates that no bounce compensation will be performed.
pin_factory (Factory or None) – See API - Pins for more information (this is an advanced feature which most users can ignore).

wait_for_active(timeout=None)¶

Pause the script until the device is activated, or the timeout is reached.

Parameters:	timeout (float or None) – Number of seconds to wait before proceeding. If this is `None` (the default), then wait indefinitely until the device is active.

wait_for_inactive(timeout=None)¶

Pause the script until the device is deactivated, or the timeout is reached.

Parameters:	timeout (float or None) – Number of seconds to wait before proceeding. If this is `None` (the default), then wait indefinitely until the device is inactive.

active_time¶: The length of time (in seconds) that the device has been active for. When the device is inactive, this is None.

inactive_time¶: The length of time (in seconds) that the device has been inactive for. When the device is active, this is None.

value¶: Returns a value representing the device’s state. Frequently, this is a boolean value, or a number between 0 and 1 but some devices use larger ranges (e.g. -1 to +1) and composite devices usually use tuples to return the states of all their subordinate components.

when_activated¶

The function to run when the device changes state from inactive to active.

This can be set to a function which accepts no (mandatory) parameters, or a Python function which accepts a single mandatory parameter (with as many optional parameters as you like). If the function accepts a single mandatory parameter, the device that activated it will be passed as that parameter.

Set this property to None (the default) to disable the event.

when_deactivated¶

The function to run when the device changes state from active to inactive.

This can be set to a function which accepts no (mandatory) parameters, or a Python function which accepts a single mandatory parameter (with as many optional parameters as you like). If the function accepts a single mandatory parameter, the device that deactivated it will be passed as that parameter.

Set this property to None (the default) to disable the event.

SmoothedInputDevice¶

class gpiozero.SmoothedInputDevice(pin, *, pull_up=False, active_state=None, threshold=0.5, queue_len=5, sample_wait=0.0, partial=False, pin_factory=None)[source]¶

Represents a generic input device which takes its value from the average of a queue of historical values.

This class extends InputDevice with a queue which is filled by a background thread which continually polls the state of the underlying device. The average (a configurable function) of the values in the queue is compared to a threshold which is used to determine the state of the is_active property.

Note

The background queue is not automatically started upon construction. This is to allow descendents to set up additional components before the queue starts reading values. Effectively this is an abstract base class.

This class is intended for use with devices which either exhibit analog behaviour (such as the charging time of a capacitor with an LDR), or those which exhibit “twitchy” behaviour (such as certain motion sensors).

Parameters:

pin (int or str) – The GPIO pin that the device is connected to. See Pin Numbering for valid pin numbers. If this is None a GPIODeviceError will be raised.
pull_up (bool or None) – See description under InputDevice for more information.
active_state (bool or None) – See description under InputDevice for more information.
threshold (float) – The value above which the device will be considered “on”.
queue_len (int) – The length of the internal queue which is filled by the background thread.
sample_wait (float) – The length of time to wait between retrieving the state of the underlying device. Defaults to 0.0 indicating that values are retrieved as fast as possible.
partial (bool) – If False (the default), attempts to read the state of the device (from the is_active property) will block until the queue has filled. If True, a value will be returned immediately, but be aware that this value is likely to fluctuate excessively.
average – The function used to average the values in the internal queue. This defaults to statistics.median() which is a good selection for discarding outliers from jittery sensors. The function specified must accept a sequence of numbers and return a single number.
ignore (frozenset or None) – The set of values which the queue should ignore, if returned from querying the device’s value.
pin_factory (Factory or None) – See API - Pins for more information (this is an advanced feature which most users can ignore).

is_active¶: Returns True if the value currently exceeds threshold and False otherwise.

partial¶: If False (the default), attempts to read the value or is_active properties will block until the queue has filled.

queue_len¶: The length of the internal queue of values which is averaged to determine the overall state of the device. This defaults to 5.

threshold¶: If value exceeds this amount, then is_active will return True.

value¶: Returns the average of the values in the internal queue. This is compared to threshold to determine whether is_active is True.

InputDevice¶

class gpiozero.InputDevice(pin, *, pull_up=False, active_state=None, pin_factory=None)[source]¶

Represents a generic GPIO input device.

This class extends GPIODevice to add facilities common to GPIO input devices. The constructor adds the optional pull_up parameter to specify how the pin should be pulled by the internal resistors. The is_active property is adjusted accordingly so that True still means active regardless of the pull_up setting.

Parameters:

pin (int or str) – The GPIO pin that the device is connected to. See Pin Numbering for valid pin numbers. If this is None a GPIODeviceError will be raised.
pull_up (bool or None) – If True, the pin will be pulled high with an internal resistor. If False (the default), the pin will be pulled low. If None, the pin will be floating. As gpiozero cannot automatically guess the active state when not pulling the pin, the active_state parameter must be passed.
active_state (bool or None) – If True, when the hardware pin state is HIGH, the software pin is HIGH. If False, the input polarity is reversed: when the hardware pin state is HIGH, the software pin state is LOW. Use this parameter to set the active state of the underlying pin when configuring it as not pulled (when pull_up is None). When pull_up is True or False, the active state is automatically set to the proper value.
pin_factory (Factory or None) – See API - Pins for more information (this is an advanced feature which most users can ignore).

is_active¶: Returns True if the device is currently active and False otherwise. This property is usually derived from value. Unlike value, this is always a boolean.

pull_up¶: If True, the device uses a pull-up resistor to set the GPIO pin “high” by default.

value¶: Returns a value representing the device’s state. Frequently, this is a boolean value, or a number between 0 and 1 but some devices use larger ranges (e.g. -1 to +1) and composite devices usually use tuples to return the states of all their subordinate components.

GPIODevice¶

class gpiozero.GPIODevice(pin, pin_factory=None)[source]¶

Extends Device. Represents a generic GPIO device and provides the services common to all single-pin GPIO devices (like ensuring two GPIO devices do no share a pin).

Parameters:	pin (int or str) – The GPIO pin that the device is connected to. See Pin Numbering for valid pin numbers. If this is `None` a `GPIODeviceError` will be raised. If the pin is already in use by another device, `GPIOPinInUse` will be raised.

close()[source]¶

Shut down the device and release all associated resources (such as GPIO pins).

This method is idempotent (can be called on an already closed device without any side-effects). It is primarily intended for interactive use at the command line. It disables the device and releases its pin(s) for use by another device.

You can attempt to do this simply by deleting an object, but unless you’ve cleaned up all references to the object this may not work (even if you’ve cleaned up all references, there’s still no guarantee the garbage collector will actually delete the object at that point). By contrast, the close method provides a means of ensuring that the object is shut down.

For example, if you have a breadboard with a buzzer connected to pin 16, but then wish to attach an LED instead:

>>> from gpiozero import *
>>> bz = Buzzer(16)
>>> bz.on()
>>> bz.off()
>>> bz.close()
>>> led = LED(16)
>>> led.blink()

Device descendents can also be used as context managers using the with statement. For example:

>>> from gpiozero import *
>>> with Buzzer(16) as bz:
...     bz.on()
...
>>> with LED(16) as led:
...     led.on()
...

closed¶: Returns True if the device is closed (see the close() method). Once a device is closed you can no longer use any other methods or properties to control or query the device.

pin¶: The Pin that the device is connected to. This will be None if the device has been closed (see the close() method). When dealing with GPIO pins, query pin.number to discover the GPIO pin (in BCM numbering) that the device is connected to.

value¶: Returns a value representing the device’s state. Frequently, this is a boolean value, or a number between 0 and 1 but some devices use larger ranges (e.g. -1 to +1) and composite devices usually use tuples to return the states of all their subordinate components.

API - Output Devices¶

These output device component interfaces have been provided for simple use of everyday components. Components must be wired up correctly before use in code.

Note

All GPIO pin numbers use Broadcom (BCM) numbering by default. See the Pin Numbering section for more information.

Regular Classes¶

The following classes are intended for general use with the devices they represent. All classes in this section are concrete (not abstract).

LED¶

class gpiozero.LED(pin, *, active_high=True, initial_value=False, pin_factory=None)[source]¶

Extends DigitalOutputDevice and represents a light emitting diode (LED).

Connect the cathode (short leg, flat side) of the LED to a ground pin; connect the anode (longer leg) to a limiting resistor; connect the other side of the limiting resistor to a GPIO pin (the limiting resistor can be placed either side of the LED).

The following example will light the LED:

from gpiozero import LED

led = LED(17)
led.on()

Parameters:

pin (int or str) – The GPIO pin which the LED is connected to. See Pin Numbering for valid pin numbers. If this is None a GPIODeviceError will be raised.
active_high (bool) – If True (the default), the LED will operate normally with the circuit described above. If False you should wire the cathode to the GPIO pin, and the anode to a 3V3 pin (via a limiting resistor).
initial_value (bool or None) – If False (the default), the LED will be off initially. If None, the LED will be left in whatever state the pin is found in when configured for output (warning: this can be on). If True, the LED will be switched on initially.
pin_factory (Factory or None) – See API - Pins for more information (this is an advanced feature which most users can ignore).

blink(on_time=1, off_time=1, n=None, background=True)¶

Make the device turn on and off repeatedly.

Parameters:

on_time (float) – Number of seconds on. Defaults to 1 second.
off_time (float) – Number of seconds off. Defaults to 1 second.
n (int or None) – Number of times to blink; None (the default) means forever.
background (bool) – If True (the default), start a background thread to continue blinking and return immediately. If False, only return when the blink is finished (warning: the default value of n will result in this method never returning).

off()¶: Turns the device off.

on()¶: Turns the device on.

toggle()¶: Reverse the state of the device. If it’s on, turn it off; if it’s off, turn it on.

is_lit¶: Returns True if the device is currently active and False otherwise. This property is usually derived from value. Unlike value, this is always a boolean.

pin¶: The Pin that the device is connected to. This will be None if the device has been closed (see the close() method). When dealing with GPIO pins, query pin.number to discover the GPIO pin (in BCM numbering) that the device is connected to.

value¶: Returns 1 if the device is currently active and 0 otherwise. Setting this property changes the state of the device.

PWMLED¶

class gpiozero.PWMLED(pin, *, active_high=True, initial_value=0, frequency=100, pin_factory=None)[source]¶

Extends PWMOutputDevice and represents a light emitting diode (LED) with variable brightness.

A typical configuration of such a device is to connect a GPIO pin to the anode (long leg) of the LED, and the cathode (short leg) to ground, with an optional resistor to prevent the LED from burning out.

Parameters:

pin (int or str) – The GPIO pin which the LED is connected to. See Pin Numbering for valid pin numbers. If this is None a GPIODeviceError will be raised.
active_high (bool) – If True (the default), the on() method will set the GPIO to HIGH. If False, the on() method will set the GPIO to LOW (the off() method always does the opposite).
initial_value (float) – If 0 (the default), the LED will be off initially. Other values between 0 and 1 can be specified as an initial brightness for the LED. Note that None cannot be specified (unlike the parent class) as there is no way to tell PWM not to alter the state of the pin.
frequency (int) – The frequency (in Hz) of pulses emitted to drive the LED. Defaults to 100Hz.
pin_factory (Factory or None) – See API - Pins for more information (this is an advanced feature which most users can ignore).

blink(on_time=1, off_time=1, fade_in_time=0, fade_out_time=0, n=None, background=True)¶

Make the device turn on and off repeatedly.

Parameters:

on_time (float) – Number of seconds on. Defaults to 1 second.
off_time (float) – Number of seconds off. Defaults to 1 second.
fade_in_time (float) – Number of seconds to spend fading in. Defaults to 0.
fade_out_time (float) – Number of seconds to spend fading out. Defaults to 0.
n (int or None) – Number of times to blink; None (the default) means forever.
background (bool) – If True (the default), start a background thread to continue blinking and return immediately. If False, only return when the blink is finished (warning: the default value of n will result in this method never returning).

off()¶: Turns the device off.

on()¶: Turns the device on.

pulse(fade_in_time=1, fade_out_time=1, n=None, background=True)¶

Make the device fade in and out repeatedly.

Parameters:

fade_in_time (float) – Number of seconds to spend fading in. Defaults to 1.
fade_out_time (float) – Number of seconds to spend fading out. Defaults to 1.
n (int or None) – Number of times to pulse; None (the default) means forever.
background (bool) – If True (the default), start a background thread to continue pulsing and return immediately. If False, only return when the pulse is finished (warning: the default value of n will result in this method never returning).

toggle()¶: Toggle the state of the device. If the device is currently off (value is 0.0), this changes it to “fully” on (value is 1.0). If the device has a duty cycle (value) of 0.1, this will toggle it to 0.9, and so on.

is_lit¶: Returns True if the device is currently active (value is non-zero) and False otherwise.

pin¶: The Pin that the device is connected to. This will be None if the device has been closed (see the close() method). When dealing with GPIO pins, query pin.number to discover the GPIO pin (in BCM numbering) that the device is connected to.

value¶: The duty cycle of the PWM device. 0.0 is off, 1.0 is fully on. Values in between may be specified for varying levels of power in the device.

RGBLED¶

class gpiozero.RGBLED(red, green, blue, *, active_high=True, initial_value=(0, 0, 0), pwm=True, pin_factory=None)[source]¶

Extends Device and represents a full color LED component (composed of red, green, and blue LEDs).

Connect the common cathode (longest leg) to a ground pin; connect each of the other legs (representing the red, green, and blue anodes) to any GPIO pins. You should use three limiting resistors (one per anode).

The following code will make the LED yellow:

from gpiozero import RGBLED

led = RGBLED(2, 3, 4)
led.color = (1, 1, 0)

The colorzero library is also supported:

from gpiozero import RGBLED
from colorzero import Color

led = RGBLED(2, 3, 4)
led.color = Color('yellow')

Parameters:

red (int or str) – The GPIO pin that controls the red component of the RGB LED. See Pin Numbering for valid pin numbers. If this is None a GPIODeviceError will be raised.
green (int or str) – The GPIO pin that controls the green component of the RGB LED.
blue (int or str) – The GPIO pin that controls the blue component of the RGB LED.
active_high (bool) – Set to True (the default) for common cathode RGB LEDs. If you are using a common anode RGB LED, set this to False.
initial_value (Color or tuple) – The initial color for the RGB LED. Defaults to black (0, 0, 0).
pwm (bool) – If True (the default), construct PWMLED instances for each component of the RGBLED. If False, construct regular LED instances, which prevents smooth color graduations.
pin_factory (Factory or None) – See API - Pins for more information (this is an advanced feature which most users can ignore).

blink(on_time=1, off_time=1, fade_in_time=0, fade_out_time=0, on_color=(1, 1, 1), off_color=(0, 0, 0), n=None, background=True)[source]¶

Make the device turn on and off repeatedly.

Parameters:

on_time (float) – Number of seconds on. Defaults to 1 second.
off_time (float) – Number of seconds off. Defaults to 1 second.
fade_in_time (float) – Number of seconds to spend fading in. Defaults to 0. Must be 0 if pwm was False when the class was constructed (ValueError will be raised if not).
fade_out_time (float) – Number of seconds to spend fading out. Defaults to 0. Must be 0 if pwm was False when the class was constructed (ValueError will be raised if not).
on_color (Color or tuple) – The color to use when the LED is “on”. Defaults to white.
off_color (Color or tuple) – The color to use when the LED is “off”. Defaults to black.
n (int or None) – Number of times to blink; None (the default) means forever.
background (bool) – If True (the default), start a background thread to continue blinking and return immediately. If False, only return when the blink is finished (warning: the default value of n will result in this method never returning).

off()[source]¶: Turn the LED off. This is equivalent to setting the LED color to black (0, 0, 0).

on()[source]¶: Turn the LED on. This equivalent to setting the LED color to white (1, 1, 1).

pulse(fade_in_time=1, fade_out_time=1, on_color=(1, 1, 1), off_color=(0, 0, 0), n=None, background=True)[source]¶

Make the device fade in and out repeatedly.

Parameters:

fade_in_time (float) – Number of seconds to spend fading in. Defaults to 1.
fade_out_time (float) – Number of seconds to spend fading out. Defaults to 1.
on_color (Color or tuple) – The color to use when the LED is “on”. Defaults to white.
off_color (Color or tuple) – The color to use when the LED is “off”. Defaults to black.
n (int or None) – Number of times to pulse; None (the default) means forever.
background (bool) – If True (the default), start a background thread to continue pulsing and return immediately. If False, only return when the pulse is finished (warning: the default value of n will result in this method never returning).

toggle()[source]¶: Toggle the state of the device. If the device is currently off (value is (0, 0, 0)), this changes it to “fully” on (value is (1, 1, 1)). If the device has a specific color, this method inverts the color.

blue¶: Represents the blue element of the LED as a Blue object.

color¶: Represents the color of the LED as a Color object.

green¶: Represents the green element of the LED as a Green object.

is_lit¶: Returns True if the LED is currently active (not black) and False otherwise.

red¶: Represents the red element of the LED as a Red object.

value¶

Represents the color of the LED as an RGB 3-tuple of (red, green, blue) where each value is between 0 and 1 if pwm was True when the class was constructed (and only 0 or 1 if not).

For example, red would be (1, 0, 0) and yellow would be (1, 1, 0), while orange would be (1, 0.5, 0).

Buzzer¶

class gpiozero.Buzzer(pin, *, active_high=True, initial_value=False, pin_factory=None)[source]¶

Extends DigitalOutputDevice and represents a digital buzzer component.

Note

This interface is only capable of simple on/off commands, and is not capable of playing a variety of tones (see TonalBuzzer).

Connect the cathode (negative pin) of the buzzer to a ground pin; connect the other side to any GPIO pin.

The following example will sound the buzzer:

from gpiozero import Buzzer

bz = Buzzer(3)
bz.on()

Parameters:

pin (int or str) – The GPIO pin which the buzzer is connected to. See Pin Numbering for valid pin numbers. If this is None a GPIODeviceError will be raised.
active_high (bool) – If True (the default), the buzzer will operate normally with the circuit described above. If False you should wire the cathode to the GPIO pin, and the anode to a 3V3 pin.
initial_value (bool or None) – If False (the default), the buzzer will be silent initially. If None, the buzzer will be left in whatever state the pin is found in when configured for output (warning: this can be on). If True, the buzzer will be switched on initially.
pin_factory (Factory or None) – See API - Pins for more information (this is an advanced feature which most users can ignore).

beep(on_time=1, off_time=1, n=None, background=True)¶

Make the device turn on and off repeatedly.

Parameters:

on_time (float) – Number of seconds on. Defaults to 1 second.
off_time (float) – Number of seconds off. Defaults to 1 second.
n (int or None) – Number of times to blink; None (the default) means forever.
background (bool) – If True (the default), start a background thread to continue blinking and return immediately. If False, only return when the blink is finished (warning: the default value of n will result in this method never returning).

off()¶: Turns the device off.

on()¶: Turns the device on.

toggle()¶: Reverse the state of the device. If it’s on, turn it off; if it’s off, turn it on.

is_active¶: Returns True if the device is currently active and False otherwise. This property is usually derived from value. Unlike value, this is always a boolean.

pin¶: The Pin that the device is connected to. This will be None if the device has been closed (see the close() method). When dealing with GPIO pins, query pin.number to discover the GPIO pin (in BCM numbering) that the device is connected to.

value¶: Returns 1 if the device is currently active and 0 otherwise. Setting this property changes the state of the device.

TonalBuzzer¶

class gpiozero.TonalBuzzer(pin, *, initial_value=None, mid_tone=Tone('A4'), octaves=1, pin_factory=None)[source]¶

Extends CompositeDevice and represents a tonal buzzer.

Parameters:

pin (int or str) – The GPIO pin which the buzzer is connected to. See Pin Numbering for valid pin numbers. If this is None a GPIODeviceError will be raised.
initial_value (float) – If None (the default), the buzzer will be off initially. Values between -1 and 1 can be specified as an initial value for the buzzer.
mid_tone (int or str) – The tone which is represented the device’s middle value (0). The default is “A4” (MIDI note 69).
octaves (int) – The number of octaves to allow away from the base note. The default is 1, meaning a value of -1 goes one octave below the base note, and one above, i.e. from A3 to A5 with the default base note of A4.
pin_factory (Factory or None) – See API - Pins for more information (this is an advanced feature which most users can ignore).

Note

Note that this class does not currently work with PiGPIOFactory.

play(tone)[source]¶

Play the given tone. This can either be an instance of Tone or can be anything that could be used to construct an instance of Tone.

For example:

>>> from gpiozero import TonalBuzzer
>>> from gpiozero.tones import Tone
>>> b = TonalBuzzer(17)
>>> b.play(Tone("A4"))
>>> b.play(Tone(220.0)) # Hz
>>> b.play(Tone(60)) # middle C in MIDI notation
>>> b.play("A4")
>>> b.play(220.0)
>>> b.play(60)

stop()[source]¶: Turn the buzzer off. This is equivalent to setting value to None.

is_active¶: Returns True if the buzzer is currently playing, otherwise False.

max_tone¶: The highest tone that the buzzer can play, i.e. the tone played when value is 1.

mid_tone¶: The middle tone available, i.e. the tone played when value is 0.

min_tone¶: The lowest tone that the buzzer can play, i.e. the tone played when value is -1.

octaves¶: The number of octaves available (above and below mid_tone).

tone¶: Returns the Tone that the buzzer is currently playing, or None if the buzzer is silent. This property can also be set to play the specified tone.

value¶: Represents the state of the buzzer as a value between -1 (representing the minimum tone) and 1 (representing the maximum tone). This can also be the special value None indicating that the buzzer is currently silent.

Motor¶

class gpiozero.Motor(forward, backward, *, pwm=True, pin_factory=None)[source]¶

Extends CompositeDevice and represents a generic motor connected to a bi-directional motor driver circuit (i.e. an H-bridge).

Attach an H-bridge motor controller to your Pi; connect a power source (e.g. a battery pack or the 5V pin) to the controller; connect the outputs of the controller board to the two terminals of the motor; connect the inputs of the controller board to two GPIO pins.

The following code will make the motor turn “forwards”:

from gpiozero import Motor

motor = Motor(17, 18)
motor.forward()

Parameters:

forward (int or str) – The GPIO pin that the forward input of the motor driver chip is connected to. See Pin Numbering for valid pin numbers. If this is None a GPIODeviceError will be raised.
backward (int or str) – The GPIO pin that the backward input of the motor driver chip is connected to. See Pin Numbering for valid pin numbers. If this is None a GPIODeviceError will be raised.
enable (int or str or None) – The GPIO pin that enables the motor. Required for some motor controller boards. See Pin Numbering for valid pin numbers.
pwm (bool) – If True (the default), construct PWMOutputDevice instances for the motor controller pins, allowing both direction and variable speed control. If False, construct DigitalOutputDevice instances, allowing only direction control.
pin_factory (Factory or None) – See API - Pins for more information (this is an advanced feature which most users can ignore).

backward(speed=1)[source]¶

Drive the motor backwards.

Parameters:	speed (float) – The speed at which the motor should turn. Can be any value between 0 (stopped) and the default 1 (maximum speed) if pwm was `True` when the class was constructed (and only 0 or 1 if not).

forward(speed=1)[source]¶

Drive the motor forwards.

Parameters:	speed (float) – The speed at which the motor should turn. Can be any value between 0 (stopped) and the default 1 (maximum speed) if pwm was `True` when the class was constructed (and only 0 or 1 if not).

reverse()[source]¶: Reverse the current direction of the motor. If the motor is currently idle this does nothing. Otherwise, the motor’s direction will be reversed at the current speed.

stop()[source]¶: Stop the motor.

is_active¶: Returns True if the motor is currently running and False otherwise.

value¶: Represents the speed of the motor as a floating point value between -1 (full speed backward) and 1 (full speed forward), with 0 representing stopped.

PhaseEnableMotor¶

class gpiozero.PhaseEnableMotor(phase, enable, *, pwm=True, pin_factory=None)[source]¶

Extends CompositeDevice and represents a generic motor connected to a Phase/Enable motor driver circuit; the phase of the driver controls whether the motor turns forwards or backwards, while enable controls the speed with PWM.

The following code will make the motor turn “forwards”:

from gpiozero import PhaseEnableMotor
motor = PhaseEnableMotor(12, 5)
motor.forward()

Parameters:

phase (int or str) – The GPIO pin that the phase (direction) input of the motor driver chip is connected to. See Pin Numbering for valid pin numbers. If this is None a GPIODeviceError will be raised.
enable (int or str) – The GPIO pin that the enable (speed) input of the motor driver chip is connected to. See Pin Numbering for valid pin numbers. If this is None a GPIODeviceError will be raised.
pwm (bool) – If True (the default), construct PWMOutputDevice instances for the motor controller pins, allowing both direction and variable speed control. If False, construct DigitalOutputDevice instances, allowing only direction control.
pin_factory (Factory or None) – See API - Pins for more information (this is an advanced feature which most users can ignore).

backward(speed=1)[source]¶

Drive the motor backwards.

Parameters:	speed (float) – The speed at which the motor should turn. Can be any value between 0 (stopped) and the default 1 (maximum speed).

forward(speed=1)[source]¶

Drive the motor forwards.

Parameters:	speed (float) – The speed at which the motor should turn. Can be any value between 0 (stopped) and the default 1 (maximum speed).

reverse()[source]¶: Reverse the current direction of the motor. If the motor is currently idle this does nothing. Otherwise, the motor’s direction will be reversed at the current speed.

stop()[source]¶: Stop the motor.

is_active¶: Returns True if the motor is currently running and False otherwise.

value¶: Represents the speed of the motor as a floating point value between -1 (full speed backward) and 1 (full speed forward).

Servo¶

class gpiozero.Servo(pin, *, initial_value=0, min_pulse_width=1/1000, max_pulse_width=2/1000, frame_width=20/1000, pin_factory=None)[source]¶

Extends CompositeDevice and represents a PWM-controlled servo motor connected to a GPIO pin.

Connect a power source (e.g. a battery pack or the 5V pin) to the power cable of the servo (this is typically colored red); connect the ground cable of the servo (typically colored black or brown) to the negative of your battery pack, or a GND pin; connect the final cable (typically colored white or orange) to the GPIO pin you wish to use for controlling the servo.

The following code will make the servo move between its minimum, maximum, and mid-point positions with a pause between each:

from gpiozero import Servo
from time import sleep

servo = Servo(17)

while True:
    servo.min()
    sleep(1)
    servo.mid()
    sleep(1)
    servo.max()
    sleep(1)

You can also use the value property to move the servo to a particular position, on a scale from -1 (min) to 1 (max) where 0 is the mid-point:

from gpiozero import Servo

servo = Servo(17)

servo.value = 0.5

Note

To reduce servo jitter, use the pigpio pin driver rather than the default RPi.GPIO driver (pigpio uses DMA sampling for much more precise edge timing). See Changing the pin factory for further information.

Parameters:

pin (int or str) – The GPIO pin that the servo is connected to. See Pin Numbering for valid pin numbers. If this is None a GPIODeviceError will be raised.
initial_value (float) – If 0 (the default), the device’s mid-point will be set initially. Other values between -1 and +1 can be specified as an initial position. None means to start the servo un-controlled (see value).
min_pulse_width (float) – The pulse width corresponding to the servo’s minimum position. This defaults to 1ms.
max_pulse_width (float) – The pulse width corresponding to the servo’s maximum position. This defaults to 2ms.
frame_width (float) – The length of time between servo control pulses measured in seconds. This defaults to 20ms which is a common value for servos.
pin_factory (Factory or None) – See API - Pins for more information (this is an advanced feature which most users can ignore).

detach()[source]¶: Temporarily disable control of the servo. This is equivalent to setting value to None.

max()[source]¶: Set the servo to its maximum position.

mid()[source]¶: Set the servo to its mid-point position.

min()[source]¶: Set the servo to its minimum position.

frame_width¶: The time between control pulses, measured in seconds.

is_active¶: Composite devices are considered “active” if any of their constituent devices have a “truthy” value.

max_pulse_width¶: The control pulse width corresponding to the servo’s maximum position, measured in seconds.

min_pulse_width¶: The control pulse width corresponding to the servo’s minimum position, measured in seconds.

pulse_width¶: Returns the current pulse width controlling the servo.

value¶: Represents the position of the servo as a value between -1 (the minimum position) and +1 (the maximum position). This can also be the special value None indicating that the servo is currently “uncontrolled”, i.e. that no control signal is being sent. Typically this means the servo’s position remains unchanged, but that it can be moved by hand.

AngularServo¶

class gpiozero.AngularServo(pin, *, initial_angle=0, min_angle=-90, max_angle=90, min_pulse_width=1/1000, max_pulse_width=2/1000, frame_width=20/1000, pin_factory=None)[source]¶

Extends Servo and represents a rotational PWM-controlled servo motor which can be set to particular angles (assuming valid minimum and maximum angles are provided to the constructor).

Connect a power source (e.g. a battery pack or the 5V pin) to the power cable of the servo (this is typically colored red); connect the ground cable of the servo (typically colored black or brown) to the negative of your battery pack, or a GND pin; connect the final cable (typically colored white or orange) to the GPIO pin you wish to use for controlling the servo.

Next, calibrate the angles that the servo can rotate to. In an interactive Python session, construct a Servo instance. The servo should move to its mid-point by default. Set the servo to its minimum value, and measure the angle from the mid-point. Set the servo to its maximum value, and again measure the angle:

>>> from gpiozero import Servo
>>> s = Servo(17)
>>> s.min() # measure the angle
>>> s.max() # measure the angle

You should now be able to construct an AngularServo instance with the correct bounds:

>>> from gpiozero import AngularServo
>>> s = AngularServo(17, min_angle=-42, max_angle=44)
>>> s.angle = 0.0
>>> s.angle
0.0
>>> s.angle = 15
>>> s.angle
15.0

Note

You can set min_angle greater than max_angle if you wish to reverse the sense of the angles (e.g. min_angle=45, max_angle=-45). This can be useful with servos that rotate in the opposite direction to your expectations of minimum and maximum.

Parameters:

pin (int or str) – The GPIO pin that the servo is connected to. See Pin Numbering for valid pin numbers. If this is None a GPIODeviceError will be raised.
initial_angle (float) – Sets the servo’s initial angle to the specified value. The default is 0. The value specified must be between min_angle and max_angle inclusive. None means to start the servo un-controlled (see value).
min_angle (float) – Sets the minimum angle that the servo can rotate to. This defaults to -90, but should be set to whatever you measure from your servo during calibration.
max_angle (float) – Sets the maximum angle that the servo can rotate to. This defaults to 90, but should be set to whatever you measure from your servo during calibration.
min_pulse_width (float) – The pulse width corresponding to the servo’s minimum position. This defaults to 1ms.
max_pulse_width (float) – The pulse width corresponding to the servo’s maximum position. This defaults to 2ms.
frame_width (float) – The length of time between servo control pulses measured in seconds. This defaults to 20ms which is a common value for servos.
pin_factory (Factory or None) – See API - Pins for more information (this is an advanced feature which most users can ignore).

max()¶: Set the servo to its maximum position.

mid()¶: Set the servo to its mid-point position.

min()¶: Set the servo to its minimum position.

angle¶

The position of the servo as an angle measured in degrees. This will only be accurate if min_angle and max_angle have been set appropriately in the constructor.

This can also be the special value None indicating that the servo is currently “uncontrolled”, i.e. that no control signal is being sent. Typically this means the servo’s position remains unchanged, but that it can be moved by hand.

is_active¶: Composite devices are considered “active” if any of their constituent devices have a “truthy” value.

max_angle¶: The maximum angle that the servo will rotate to when max() is called.

min_angle¶: The minimum angle that the servo will rotate to when min() is called.

value¶: Represents the position of the servo as a value between -1 (the minimum position) and +1 (the maximum position). This can also be the special value None indicating that the servo is currently “uncontrolled”, i.e. that no control signal is being sent. Typically this means the servo’s position remains unchanged, but that it can be moved by hand.

Base Classes¶

The classes in the sections above are derived from a series of base classes, some of which are effectively abstract. The classes form the (partial) hierarchy displayed in the graph below (abstract classes are shaded lighter than concrete classes):

The following sections document these base classes for advanced users that wish to construct classes for their own devices.

DigitalOutputDevice¶

class gpiozero.DigitalOutputDevice(pin, *, active_high=True, initial_value=False, pin_factory=None)[source]¶

Represents a generic output device with typical on/off behaviour.

This class extends OutputDevice with a blink() method which uses an optional background thread to handle toggling the device state without further interaction.

Parameters:

pin (int or str) – The GPIO pin that the device is connected to. See Pin Numbering for valid pin numbers. If this is None a GPIODeviceError will be raised.
active_high (bool) – If True (the default), the on() method will set the GPIO to HIGH. If False, the on() method will set the GPIO to LOW (the off() method always does the opposite).
initial_value (bool or None) – If False (the default), the device will be off initially. If None, the device will be left in whatever state the pin is found in when configured for output (warning: this can be on). If True, the device will be switched on initially.
pin_factory (Factory or None) – See API - Pins for more information (this is an advanced feature which most users can ignore).

blink(on_time=1, off_time=1, n=None, background=True)[source]¶

Make the device turn on and off repeatedly.

Parameters:

on_time (float) – Number of seconds on. Defaults to 1 second.
off_time (float) – Number of seconds off. Defaults to 1 second.
n (int or None) – Number of times to blink; None (the default) means forever.
background (bool) – If True (the default), start a background thread to continue blinking and return immediately. If False, only return when the blink is finished (warning: the default value of n will result in this method never returning).

off()[source]¶: Turns the device off.

on()[source]¶: Turns the device on.

value¶: Returns 1 if the device is currently active and 0 otherwise. Setting this property changes the state of the device.

PWMOutputDevice¶

class gpiozero.PWMOutputDevice(pin, *, active_high=True, initial_value=0, frequency=100, pin_factory=None)[source]¶

Generic output device configured for pulse-width modulation (PWM).

Parameters:

pin (int or str) – The GPIO pin that the device is connected to. See Pin Numbering for valid pin numbers. If this is None a GPIODeviceError will be raised.
active_high (bool) – If True (the default), the on() method will set the GPIO to HIGH. If False, the on() method will set the GPIO to LOW (the off() method always does the opposite).
initial_value (float) – If 0 (the default), the device’s duty cycle will be 0 initially. Other values between 0 and 1 can be specified as an initial duty cycle. Note that None cannot be specified (unlike the parent class) as there is no way to tell PWM not to alter the state of the pin.
frequency (int) – The frequency (in Hz) of pulses emitted to drive the device. Defaults to 100Hz.
pin_factory (Factory or None) – See API - Pins for more information (this is an advanced feature which most users can ignore).

blink(on_time=1, off_time=1, fade_in_time=0, fade_out_time=0, n=None, background=True)[source]¶

Make the device turn on and off repeatedly.

Parameters:

on_time (float) – Number of seconds on. Defaults to 1 second.
off_time (float) – Number of seconds off. Defaults to 1 second.
fade_in_time (float) – Number of seconds to spend fading in. Defaults to 0.
fade_out_time (float) – Number of seconds to spend fading out. Defaults to 0.
n (int or None) – Number of times to blink; None (the default) means forever.
background (bool) – If True (the default), start a background thread to continue blinking and return immediately. If False, only return when the blink is finished (warning: the default value of n will result in this method never returning).

off()[source]¶: Turns the device off.

on()[source]¶: Turns the device on.

pulse(fade_in_time=1, fade_out_time=1, n=None, background=True)[source]¶

Make the device fade in and out repeatedly.

Parameters:

fade_in_time (float) – Number of seconds to spend fading in. Defaults to 1.
fade_out_time (float) – Number of seconds to spend fading out. Defaults to 1.
n (int or None) – Number of times to pulse; None (the default) means forever.
background (bool) – If True (the default), start a background thread to continue pulsing and return immediately. If False, only return when the pulse is finished (warning: the default value of n will result in this method never returning).

toggle()[source]¶: Toggle the state of the device. If the device is currently off (value is 0.0), this changes it to “fully” on (value is 1.0). If the device has a duty cycle (value) of 0.1, this will toggle it to 0.9, and so on.

frequency¶: The frequency of the pulses used with the PWM device, in Hz. The default is 100Hz.

is_active¶: Returns True if the device is currently active (value is non-zero) and False otherwise.

value¶: The duty cycle of the PWM device. 0.0 is off, 1.0 is fully on. Values in between may be specified for varying levels of power in the device.

OutputDevice¶

class gpiozero.OutputDevice(pin, *, active_high=True, initial_value=False, pin_factory=None)[source]¶

Represents a generic GPIO output device.

This class extends GPIODevice to add facilities common to GPIO output devices: an on() method to switch the device on, a corresponding off() method, and a toggle() method.

Parameters:

pin (int or str) – The GPIO pin that the device is connected to. See Pin Numbering for valid pin numbers. If this is None a GPIODeviceError will be raised.
active_high (bool) – If True (the default), the on() method will set the GPIO to HIGH. If False, the on() method will set the GPIO to LOW (the off() method always does the opposite).
initial_value (bool or None) – If False (the default), the device will be off initially. If None, the device will be left in whatever state the pin is found in when configured for output (warning: this can be on). If True, the device will be switched on initially.
pin_factory (Factory or None) – See API - Pins for more information (this is an advanced feature which most users can ignore).

off()[source]¶: Turns the device off.

on()[source]¶: Turns the device on.

toggle()[source]¶: Reverse the state of the device. If it’s on, turn it off; if it’s off, turn it on.

active_high¶

When True, the value property is True when the device’s pin is high. When False the value property is True when the device’s pin is low (i.e. the value is inverted).

This property can be set after construction; be warned that changing it will invert value (i.e. changing this property doesn’t change the device’s pin state - it just changes how that state is interpreted).

value¶: Returns 1 if the device is currently active and 0 otherwise. Setting this property changes the state of the device.

GPIODevice¶

class gpiozero.GPIODevice(pin, *, pin_factory=None)[source]

Extends Device. Represents a generic GPIO device and provides the services common to all single-pin GPIO devices (like ensuring two GPIO devices do no share a pin).

Parameters:	pin (int or str) – The GPIO pin that the device is connected to. See Pin Numbering for valid pin numbers. If this is `None` a `GPIODeviceError` will be raised. If the pin is already in use by another device, `GPIOPinInUse` will be raised.

close()[source]

Shut down the device and release all associated resources (such as GPIO pins).

This method is idempotent (can be called on an already closed device without any side-effects). It is primarily intended for interactive use at the command line. It disables the device and releases its pin(s) for use by another device.

You can attempt to do this simply by deleting an object, but unless you’ve cleaned up all references to the object this may not work (even if you’ve cleaned up all references, there’s still no guarantee the garbage collector will actually delete the object at that point). By contrast, the close method provides a means of ensuring that the object is shut down.

For example, if you have a breadboard with a buzzer connected to pin 16, but then wish to attach an LED instead:

>>> from gpiozero import *
>>> bz = Buzzer(16)
>>> bz.on()
>>> bz.off()
>>> bz.close()
>>> led = LED(16)
>>> led.blink()

Device descendents can also be used as context managers using the with statement. For example:

>>> from gpiozero import *
>>> with Buzzer(16) as bz:
...     bz.on()
...
>>> with LED(16) as led:
...     led.on()
...

closed: Returns True if the device is closed (see the close() method). Once a device is closed you can no longer use any other methods or properties to control or query the device.

pin: The Pin that the device is connected to. This will be None if the device has been closed (see the close() method). When dealing with GPIO pins, query pin.number to discover the GPIO pin (in BCM numbering) that the device is connected to.

value: Returns a value representing the device’s state. Frequently, this is a boolean value, or a number between 0 and 1 but some devices use larger ranges (e.g. -1 to +1) and composite devices usually use tuples to return the states of all their subordinate components.

API - SPI Devices¶

SPI stands for Serial Peripheral Interface and is a mechanism allowing compatible devices to communicate with the Pi. SPI is a four-wire protocol meaning it usually requires four pins to operate:

A “clock” pin which provides timing information.
A “MOSI” pin (Master Out, Slave In) which the Pi uses to send information to the device.
A “MISO” pin (Master In, Slave Out) which the Pi uses to receive information from the device.
A “select” pin which the Pi uses to indicate which device it’s talking to. This last pin is necessary because multiple devices can share the clock, MOSI, and MISO pins, but only one device can be connected to each select pin.

The gpiozero library provides two SPI implementations:

A software based implementation. This is always available, can use any four GPIO pins for SPI communication, but is rather slow and won’t work with all devices.
A hardware based implementation. This is only available when the SPI kernel module is loaded, and the Python spidev library is available. It can only use specific pins for SPI communication (GPIO11=clock, GPIO10=MOSI, GPIO9=MISO, while GPIO8 is select for device 0 and GPIO7 is select for device 1). However, it is extremely fast and works with all devices.

SPI keyword args¶

When constructing an SPI device there are two schemes for specifying which pins it is connected to:

You can specify port and device keyword arguments. The port parameter must be 0 (there is only one user-accessible hardware SPI interface on the Pi using GPIO11 as the clock pin, GPIO10 as the MOSI pin, and GPIO9 as the MISO pin), while the device parameter must be 0 or 1. If device is 0, the select pin will be GPIO8. If device is 1, the select pin will be GPIO7.
Alternatively you can specify clock_pin, mosi_pin, miso_pin, and select_pin keyword arguments. In this case the pins can be any 4 GPIO pins (remember that SPI devices can share clock, MOSI, and MISO pins, but not select pins - the gpiozero library will enforce this restriction).

You cannot mix these two schemes, i.e. attempting to specify port and clock_pin will result in SPIBadArgs being raised. However, you can omit any arguments from either scheme. The defaults are:

port and device both default to 0.
clock_pin defaults to 11, mosi_pin defaults to 10, miso_pin defaults to 9, and select_pin defaults to 8.
As with other GPIO based devices you can optionally specify a pin_factory argument overriding the default pin factory (see API - Pins for more information).

Hence the following constructors are all equivalent:

from gpiozero import MCP3008

MCP3008(channel=0)
MCP3008(channel=0, device=0)
MCP3008(channel=0, port=0, device=0)
MCP3008(channel=0, select_pin=8)
MCP3008(channel=0, clock_pin=11, mosi_pin=10, miso_pin=9, select_pin=8)

Note that the defaults describe equivalent sets of pins and that these pins are compatible with the hardware implementation. Regardless of which scheme you use, gpiozero will attempt to use the hardware implementation if it is available and if the selected pins are compatible, falling back to the software implementation if not.

Analog to Digital Converters (ADC)¶

The following classes are intended for general use with the integrated circuits they are named after. All classes in this section are concrete (not abstract).

MCP3001¶

class gpiozero.MCP3001(max_voltage=3.3, **spi_args)[source]¶

The MCP3001 is a 10-bit analog to digital converter with 1 channel. Please note that the MCP3001 always operates in differential mode, measuring the value of IN+ relative to IN-.

value¶: The current value read from the device, scaled to a value between 0 and 1 (or -1 to +1 for certain devices operating in differential mode).

MCP3002¶

class gpiozero.MCP3002(channel=0, differential=False, max_voltage=3.3, **spi_args)[source]¶

The MCP3002 is a 10-bit analog to digital converter with 2 channels (0-1).

channel¶: The channel to read data from. The MCP3008/3208/3304 have 8 channels (0-7), while the MCP3004/3204/3302 have 4 channels (0-3), the MCP3002/3202 have 2 channels (0-1), and the MCP3001/3201/3301 only have 1 channel.

differential¶

If True, the device is operated in differential mode. In this mode one channel (specified by the channel attribute) is read relative to the value of a second channel (implied by the chip’s design).

Please refer to the device data-sheet to determine which channel is used as the relative base value (for example, when using an MCP3008 in differential mode, channel 0 is read relative to channel 1).

value¶: The current value read from the device, scaled to a value between 0 and 1 (or -1 to +1 for certain devices operating in differential mode).

MCP3004¶

class gpiozero.MCP3004(channel=0, differential=False, max_voltage=3.3, **spi_args)[source]¶

The MCP3004 is a 10-bit analog to digital converter with 4 channels (0-3).

channel¶: The channel to read data from. The MCP3008/3208/3304 have 8 channels (0-7), while the MCP3004/3204/3302 have 4 channels (0-3), the MCP3002/3202 have 2 channels (0-1), and the MCP3001/3201/3301 only have 1 channel.

differential¶

If True, the device is operated in differential mode. In this mode one channel (specified by the channel attribute) is read relative to the value of a second channel (implied by the chip’s design).

Please refer to the device data-sheet to determine which channel is used as the relative base value (for example, when using an MCP3008 in differential mode, channel 0 is read relative to channel 1).

value¶: The current value read from the device, scaled to a value between 0 and 1 (or -1 to +1 for certain devices operating in differential mode).

MCP3008¶

class gpiozero.MCP3008(channel=0, differential=False, max_voltage=3.3, **spi_args)[source]¶

The MCP3008 is a 10-bit analog to digital converter with 8 channels (0-7).

channel¶: The channel to read data from. The MCP3008/3208/3304 have 8 channels (0-7), while the MCP3004/3204/3302 have 4 channels (0-3), the MCP3002/3202 have 2 channels (0-1), and the MCP3001/3201/3301 only have 1 channel.

differential¶

If True, the device is operated in differential mode. In this mode one channel (specified by the channel attribute) is read relative to the value of a second channel (implied by the chip’s design).

Please refer to the device data-sheet to determine which channel is used as the relative base value (for example, when using an MCP3008 in differential mode, channel 0 is read relative to channel 1).

value¶: The current value read from the device, scaled to a value between 0 and 1 (or -1 to +1 for certain devices operating in differential mode).

MCP3201¶

class gpiozero.MCP3201(max_voltage=3.3, **spi_args)[source]¶

The MCP3201 is a 12-bit analog to digital converter with 1 channel. Please note that the MCP3201 always operates in differential mode, measuring the value of IN+ relative to IN-.

value¶: The current value read from the device, scaled to a value between 0 and 1 (or -1 to +1 for certain devices operating in differential mode).

MCP3202¶

class gpiozero.MCP3202(channel=0, differential=False, max_voltage=3.3, **spi_args)[source]¶

The MCP3202 is a 12-bit analog to digital converter with 2 channels (0-1).

channel¶: The channel to read data from. The MCP3008/3208/3304 have 8 channels (0-7), while the MCP3004/3204/3302 have 4 channels (0-3), the MCP3002/3202 have 2 channels (0-1), and the MCP3001/3201/3301 only have 1 channel.

differential¶

If True, the device is operated in differential mode. In this mode one channel (specified by the channel attribute) is read relative to the value of a second channel (implied by the chip’s design).

Please refer to the device data-sheet to determine which channel is used as the relative base value (for example, when using an MCP3008 in differential mode, channel 0 is read relative to channel 1).

value¶: The current value read from the device, scaled to a value between 0 and 1 (or -1 to +1 for certain devices operating in differential mode).

MCP3204¶

class gpiozero.MCP3204(channel=0, differential=False, max_voltage=3.3, **spi_args)[source]¶

The MCP3204 is a 12-bit analog to digital converter with 4 channels (0-3).

channel¶: The channel to read data from. The MCP3008/3208/3304 have 8 channels (0-7), while the MCP3004/3204/3302 have 4 channels (0-3), the MCP3002/3202 have 2 channels (0-1), and the MCP3001/3201/3301 only have 1 channel.

differential¶

If True, the device is operated in differential mode. In this mode one channel (specified by the channel attribute) is read relative to the value of a second channel (implied by the chip’s design).

Please refer to the device data-sheet to determine which channel is used as the relative base value (for example, when using an MCP3008 in differential mode, channel 0 is read relative to channel 1).

value¶: The current value read from the device, scaled to a value between 0 and 1 (or -1 to +1 for certain devices operating in differential mode).

MCP3208¶

class gpiozero.MCP3208(channel=0, differential=False, max_voltage=3.3, **spi_args)[source]¶

The MCP3208 is a 12-bit analog to digital converter with 8 channels (0-7).

channel¶: The channel to read data from. The MCP3008/3208/3304 have 8 channels (0-7), while the MCP3004/3204/3302 have 4 channels (0-3), the MCP3002/3202 have 2 channels (0-1), and the MCP3001/3201/3301 only have 1 channel.

differential¶

If True, the device is operated in differential mode. In this mode one channel (specified by the channel attribute) is read relative to the value of a second channel (implied by the chip’s design).

Please refer to the device data-sheet to determine which channel is used as the relative base value (for example, when using an MCP3008 in differential mode, channel 0 is read relative to channel 1).

value¶: The current value read from the device, scaled to a value between 0 and 1 (or -1 to +1 for certain devices operating in differential mode).

MCP3301¶

class gpiozero.MCP3301(max_voltage=3.3, **spi_args)[source]¶

The MCP3301 is a signed 13-bit analog to digital converter. Please note that the MCP3301 always operates in differential mode measuring the difference between IN+ and IN-. Its output value is scaled from -1 to +1.

value¶: The current value read from the device, scaled to a value between 0 and 1 (or -1 to +1 for devices operating in differential mode).

MCP3302¶

class gpiozero.MCP3302(channel=0, differential=False, max_voltage=3.3, **spi_args)[source]¶

The MCP3302 is a 12/13-bit analog to digital converter with 4 channels (0-3). When operated in differential mode, the device outputs a signed 13-bit value which is scaled from -1 to +1. When operated in single-ended mode (the default), the device outputs an unsigned 12-bit value scaled from 0 to 1.

channel¶: The channel to read data from. The MCP3008/3208/3304 have 8 channels (0-7), while the MCP3004/3204/3302 have 4 channels (0-3), the MCP3002/3202 have 2 channels (0-1), and the MCP3001/3201/3301 only have 1 channel.

differential¶

If True, the device is operated in differential mode. In this mode one channel (specified by the channel attribute) is read relative to the value of a second channel (implied by the chip’s design).

Please refer to the device data-sheet to determine which channel is used as the relative base value (for example, when using an MCP3304 in differential mode, channel 0 is read relative to channel 1).

value¶: The current value read from the device, scaled to a value between 0 and 1 (or -1 to +1 for devices operating in differential mode).

MCP3304¶

class gpiozero.MCP3304(channel=0, differential=False, max_voltage=3.3, **spi_args)[source]¶

The MCP3304 is a 12/13-bit analog to digital converter with 8 channels (0-7). When operated in differential mode, the device outputs a signed 13-bit value which is scaled from -1 to +1. When operated in single-ended mode (the default), the device outputs an unsigned 12-bit value scaled from 0 to 1.

channel¶: The channel to read data from. The MCP3008/3208/3304 have 8 channels (0-7), while the MCP3004/3204/3302 have 4 channels (0-3), the MCP3002/3202 have 2 channels (0-1), and the MCP3001/3201/3301 only have 1 channel.

differential¶

If True, the device is operated in differential mode. In this mode one channel (specified by the channel attribute) is read relative to the value of a second channel (implied by the chip’s design).

Please refer to the device data-sheet to determine which channel is used as the relative base value (for example, when using an MCP3304 in differential mode, channel 0 is read relative to channel 1).

value¶: The current value read from the device, scaled to a value between 0 and 1 (or -1 to +1 for devices operating in differential mode).

Base Classes¶

The classes in the sections above are derived from a series of base classes, some of which are effectively abstract. The classes form the (partial) hierarchy displayed in the graph below (abstract classes are shaded lighter than concrete classes):

The following sections document these base classes for advanced users that wish to construct classes for their own devices.

AnalogInputDevice¶

class gpiozero.AnalogInputDevice(bits, max_voltage=3.3, **spi_args)[source]¶

Represents an analog input device connected to SPI (serial interface).

Typical analog input devices are analog to digital converters (ADCs). Several classes are provided for specific ADC chips, including MCP3004, MCP3008, MCP3204, and MCP3208.

The following code demonstrates reading the first channel of an MCP3008 chip attached to the Pi’s SPI pins:

from gpiozero import MCP3008

pot = MCP3008(0)
print(pot.value)

The value attribute is normalized such that its value is always between 0.0 and 1.0 (or in special cases, such as differential sampling, -1 to +1). Hence, you can use an analog input to control the brightness of a PWMLED like so:

from gpiozero import MCP3008, PWMLED

pot = MCP3008(0)
led = PWMLED(17)
led.source = pot

The voltage attribute reports values between 0.0 and max_voltage (which defaults to 3.3, the logic level of the GPIO pins).

bits¶: The bit-resolution of the device/channel.

max_voltage¶: The voltage required to set the device’s value to 1.

raw_value¶: The raw value as read from the device.

value¶: The current value read from the device, scaled to a value between 0 and 1 (or -1 to +1 for certain devices operating in differential mode).

voltage¶: The current voltage read from the device. This will be a value between 0 and the max_voltage parameter specified in the constructor.

SPIDevice¶

class gpiozero.SPIDevice(**spi_args)[source]¶

Extends Device. Represents a device that communicates via the SPI protocol.

See SPI keyword args for information on the keyword arguments that can be specified with the constructor.

close()[source]¶

Shut down the device and release all associated resources (such as GPIO pins).

This method is idempotent (can be called on an already closed device without any side-effects). It is primarily intended for interactive use at the command line. It disables the device and releases its pin(s) for use by another device.

You can attempt to do this simply by deleting an object, but unless you’ve cleaned up all references to the object this may not work (even if you’ve cleaned up all references, there’s still no guarantee the garbage collector will actually delete the object at that point). By contrast, the close method provides a means of ensuring that the object is shut down.

For example, if you have a breadboard with a buzzer connected to pin 16, but then wish to attach an LED instead:

>>> from gpiozero import *
>>> bz = Buzzer(16)
>>> bz.on()
>>> bz.off()
>>> bz.close()
>>> led = LED(16)
>>> led.blink()

Device descendents can also be used as context managers using the with statement. For example:

>>> from gpiozero import *
>>> with Buzzer(16) as bz:
...     bz.on()
...
>>> with LED(16) as led:
...     led.on()
...

closed¶: Returns True if the device is closed (see the close() method). Once a device is closed you can no longer use any other methods or properties to control or query the device.

API - Boards and Accessories¶

These additional interfaces are provided to group collections of components together for ease of use, and as examples. They are composites made up of components from the various API - Input Devices and API - Output Devices provided by GPIO Zero. See those pages for more information on using components individually.

Note

All GPIO pin numbers use Broadcom (BCM) numbering by default. See the Pin Numbering section for more information.

Regular Classes¶

The following classes are intended for general use with the devices they are named after. All classes in this section are concrete (not abstract).

LEDBoard¶

class gpiozero.LEDBoard(*pins, pwm=False, active_high=True, initial_value=False, pin_factory=None, **named_pins)[source]¶

Extends LEDCollection and represents a generic LED board or collection of LEDs.

The following example turns on all the LEDs on a board containing 5 LEDs attached to GPIO pins 2 through 6:

from gpiozero import LEDBoard

leds = LEDBoard(2, 3, 4, 5, 6)
leds.on()

Parameters:

*pins – Specify the GPIO pins that the LEDs of the board are attached to. See Pin Numbering for valid pin numbers. You can designate as many pins as necessary. You can also specify LEDBoard instances to create trees of LEDs.
pwm (bool) – If True, construct PWMLED instances for each pin. If False (the default), construct regular LED instances.
active_high (bool) – If True (the default), the on() method will set all the associated pins to HIGH. If False, the on() method will set all pins to LOW (the off() method always does the opposite).
initial_value (bool or None) – If False (the default), all LEDs will be off initially. If None, each device will be left in whatever state the pin is found in when configured for output (warning: this can be on). If True, the device will be switched on initially.
pin_factory (Factory or None) – See API - Pins for more information (this is an advanced feature which most users can ignore).
**named_pins – Specify GPIO pins that LEDs of the board are attached to, associating each LED with a property name. You can designate as many pins as necessary and use any names, provided they’re not already in use by something else. You can also specify LEDBoard instances to create trees of LEDs.

blink(on_time=1, off_time=1, fade_in_time=0, fade_out_time=0, n=None, background=True)[source]¶

Make all the LEDs turn on and off repeatedly.

Parameters:

on_time (float) – Number of seconds on. Defaults to 1 second.
off_time (float) – Number of seconds off. Defaults to 1 second.
fade_in_time (float) – Number of seconds to spend fading in. Defaults to 0. Must be 0 if pwm was False when the class was constructed (ValueError will be raised if not).
fade_out_time (float) – Number of seconds to spend fading out. Defaults to 0. Must be 0 if pwm was False when the class was constructed (ValueError will be raised if not).
n (int or None) – Number of times to blink; None (the default) means forever.
background (bool) – If True, start a background thread to continue blinking and return immediately. If False, only return when the blink is finished (warning: the default value of n will result in this method never returning).

off(*args)[source]¶

If no arguments are specified, turn all the LEDs off. If arguments are specified, they must be the indexes of the LEDs you wish to turn off. For example:

from gpiozero import LEDBoard

leds = LEDBoard(2, 3, 4, 5)
leds.on()      # turn on all LEDs
leds.off(0)    # turn off the first LED (pin 2)
leds.off(-1)   # turn off the last LED (pin 5)
leds.off(1, 2) # turn off the middle LEDs (pins 3 and 4)
leds.on()      # turn on all LEDs

If blink() is currently active, it will be stopped first.

Parameters:	args (int) – The index(es) of the LED(s) to turn off. If no indexes are specified turn off all LEDs.

on(*args)[source]¶

If no arguments are specified, turn all the LEDs on. If arguments are specified, they must be the indexes of the LEDs you wish to turn on. For example:

from gpiozero import LEDBoard

leds = LEDBoard(2, 3, 4, 5)
leds.on(0)    # turn on the first LED (pin 2)
leds.on(-1)   # turn on the last LED (pin 5)
leds.on(1, 2) # turn on the middle LEDs (pins 3 and 4)
leds.off()    # turn off all LEDs
leds.on()     # turn on all LEDs

If blink() is currently active, it will be stopped first.

Parameters:	args (int) – The index(es) of the LED(s) to turn on. If no indexes are specified turn on all LEDs.

pulse(fade_in_time=1, fade_out_time=1, n=None, background=True)[source]¶

Make all LEDs fade in and out repeatedly. Note that this method will only work if the pwm parameter was True at construction time.

Parameters:

fade_in_time (float) – Number of seconds to spend fading in. Defaults to 1.
fade_out_time (float) – Number of seconds to spend fading out. Defaults to 1.
n (int or None) – Number of times to blink; None (the default) means forever.
background (bool) – If True (the default), start a background thread to continue blinking and return immediately. If False, only return when the blink is finished (warning: the default value of n will result in this method never returning).

toggle(*args)[source]¶

If no arguments are specified, toggle the state of all LEDs. If arguments are specified, they must be the indexes of the LEDs you wish to toggle. For example:

from gpiozero import LEDBoard

leds = LEDBoard(2, 3, 4, 5)
leds.toggle(0)   # turn on the first LED (pin 2)
leds.toggle(-1)  # turn on the last LED (pin 5)
leds.toggle()    # turn the first and last LED off, and the
                 # middle pair on

If blink() is currently active, it will be stopped first.

Parameters:	args (int) – The index(es) of the LED(s) to toggle. If no indexes are specified toggle the state of all LEDs.

LEDBarGraph¶

class gpiozero.LEDBarGraph(*pins, pwm=False, active_high=True, initial_value=0, pin_factory=None)[source]¶

Extends LEDCollection to control a line of LEDs representing a bar graph. Positive values (0 to 1) light the LEDs from first to last. Negative values (-1 to 0) light the LEDs from last to first.

The following example demonstrates turning on the first two and last two LEDs in a board containing five LEDs attached to GPIOs 2 through 6:

from gpiozero import LEDBarGraph
from time import sleep

graph = LEDBarGraph(2, 3, 4, 5, 6)
graph.value = 2/5  # Light the first two LEDs only
sleep(1)
graph.value = -2/5 # Light the last two LEDs only
sleep(1)
graph.off()

As with all other output devices, source and values are supported:

from gpiozero import LEDBarGraph, MCP3008
from signal import pause

graph = LEDBarGraph(2, 3, 4, 5, 6, pwm=True)
pot = MCP3008(channel=0)

graph.source = pot

pause()

Parameters:

*pins – Specify the GPIO pins that the LEDs of the bar graph are attached to. See Pin Numbering for valid pin numbers. You can designate as many pins as necessary.
pwm (bool) – If True, construct PWMLED instances for each pin. If False (the default), construct regular LED instances. This parameter can only be specified as a keyword parameter.
active_high (bool) – If True (the default), the on() method will set all the associated pins to HIGH. If False, the on() method will set all pins to LOW (the off() method always does the opposite). This parameter can only be specified as a keyword parameter.
initial_value (float) – The initial value of the graph given as a float between -1 and +1. Defaults to 0.0. This parameter can only be specified as a keyword parameter.
pin_factory (Factory or None) – See API - Pins for more information (this is an advanced feature which most users can ignore).

lit_count¶: The number of LEDs on the bar graph actually lit up. Note that just like value, this can be negative if the LEDs are lit from last to first.

source¶: The iterable to use as a source of values for value.

value¶

The value of the LED bar graph. When no LEDs are lit, the value is 0. When all LEDs are lit, the value is 1. Values between 0 and 1 light LEDs linearly from first to last. Values between 0 and -1 light LEDs linearly from last to first.

To light a particular number of LEDs, simply divide that number by the number of LEDs. For example, if your graph contains 3 LEDs, the following will light the first:

from gpiozero import LEDBarGraph

graph = LEDBarGraph(12, 16, 19)
graph.value = 1/3

Note

Setting value to -1 will light all LEDs. However, querying it subsequently will return 1 as both representations are the same in hardware. The readable range of value is effectively -1 < value <= 1.

values¶: An infinite iterator of values read from value.

LEDCharDisplay¶

class gpiozero.LEDCharDisplay(*pins, dp=None, font=None, pwm=False, active_high=True, initial_value=' ', pin_factory=None)[source]¶

Extends LEDCollection for a multi-segment LED display.

Multi-segment LED displays typically have 7 pins (labelled “a” through “g”) representing 7 LEDs layed out in a figure-of-8 fashion. Frequently, an eigth pin labelled “dp” is included for a trailing decimal-point:

     a
   ━━━━━
f ┃     ┃ b
  ┃  g  ┃
   ━━━━━
e ┃     ┃ c
  ┃     ┃
   ━━━━━ • dp
     d

Other common layouts are 9, 14, and 16 segment displays which include additional segments permitting more accurate renditions of alphanumerics. For example:

     a
   ━━━━━
f ┃╲i┃j╱┃ b
  ┃ ╲┃╱k┃
  g━━ ━━h
e ┃ ╱┃╲n┃ c
  ┃╱l┃m╲┃
   ━━━━━ • dp
     d

Such displays have either a common anode, or common cathode pin. This class defaults to the latter; when using a common anode display active_high should be set to False.

Instances of this class can be used to display characters or control individual LEDs on the display. For example:

from gpiozero import LEDCharDisplay

char = LEDCharDisplay(4, 5, 6, 7, 8, 9, 10, active_high=False)
char.value = 'C'

If the class is constructed with 7 or 14 segments, a default font will be loaded, mapping some ASCII characters to typical layouts. In other cases, the default mapping will simply assign ” ” (space) to all LEDs off. You can assign your own mapping at construction time or after instantiation.

While the example above shows the display with a str value, theoretically the font can map any value that can be the key in a dict, so the value of the display can be likewise be any valid key value (e.g. you could map integer digits to LED patterns). That said, there is one exception to this: when dp is specified to enable the decimal-point, the value must be a str as the presence or absence of a “.” suffix indicates whether the dp LED is lit.

Parameters:

*pins – Specify the GPIO pins that the multi-segment display is attached to. Pins should be in the LED segment order A, B, C, D, E, F, G, and will be named automatically by the class. If a decimal-point pin is present, specify it separately as the dp parameter.
dp (int or str) – If a decimal-point segment is present, specify it as this named parameter.
font (dict or None) – A mapping of values (typically characters, but may also be numbers) to tuples of LED states. A default mapping for ASCII characters is provided for 7 and 14 segment displays.
pwm (bool) – If True, construct PWMLED instances for each pin. If False (the default), construct regular LED instances.
active_high (bool) – If True (the default), the on() method will set all the associated pins to HIGH. If False, the on() method will set all pins to LOW (the off() method always does the opposite).
initial_value – The initial value to display. Defaults to space (” “) which typically maps to all LEDs being inactive. If None, each device will be left in whatever state the pin is found in when configured for output (warning: this can be on).
pin_factory (Factory or None) – See API - Pins for more information (this is an advanced feature which most users can ignore).

font¶

An LEDCharFont mapping characters to tuples of LED states. The font is mutable after construction. You can assign a tuple of LED states to a character to modify the font, delete an existing character in the font, or assign a mapping of characters to tuples to replace the entire font.

Note that modifying the font never alters the underlying LED states. Only assignment to value, or calling the inherited LEDCollection methods (on(), off(), etc.) modifies LED states. However, modifying the font may alter the character returned by querying value.

value¶

The character the display should show. This is mapped by the current font to a tuple of LED states which is applied to the underlying LED objects when this attribute is set.

When queried, the current LED states are looked up in the font to determine the character shown. If the current LED states do not correspond to any character in the font, the value is None.

It is possible for multiple characters in the font to map to the same LED states (e.g. S and 5). In this case, if the font was constructed from an ordered mapping (which is the default), then the first matching mapping will always be returned. This also implies that the value queried need not match the value set.

LEDMultiCharDisplay¶

class gpiozero.LEDMultiCharDisplay(char, *pins, active_high=True, initial_value=None, pin_factory=None)[source]¶

Wraps LEDCharDisplay for multi-character multiplexed LED character displays.

The class is constructed with a char which is an instance of the LEDCharDisplay class, capable of controlling the LEDs in one character of the display, and an additional set of pins that represent the common cathode (or anode) of each character.

Warning

You should not attempt to connect the common cathode (or anode) off each character directly to a GPIO. Rather, use a set of transistors (or some other suitable component capable of handling the current of all the segment LEDs simultaneously) to connect the common cathode to ground (or the common anode to the supply) and control those transistors from the GPIOs specified under pins.

The active_high parameter defaults to True. Note that it only applies to the specified pins, which are assumed to be controlling a set of transistors (hence the default). The specified char will use its own active_high parameter. Finally, initial_value defaults to a tuple of value attribute of the specified display multiplied by the number of pins provided.

When the value is set such that one or more characters in the display differ in value, a background thread is implicitly started to rotate the active character, relying on persistence of vision to display the complete value.

plex_delay¶: The delay (measured in seconds) in the loop used to switch each character in the multiplexed display on. Defaults to 0.005 seconds which is generally sufficient to provide a “stable” (non-flickery) display.

value¶

The sequence of values to display.

This can be any sequence containing keys from the font of the associated character display. For example, if the value consists only of single-character strings, it’s valid to assign a string to this property (as a string is simply a sequence of individual character keys):

from gpiozero import LEDCharDisplay, LEDMultiCharDisplay

c = LEDCharDisplay(4, 5, 6, 7, 8, 9, 10)
d = LEDMultiCharDisplay(c, 19, 20, 21, 22)
d.value = 'LEDS'

However, things get more complicated if a decimal point is in use as then this class needs to know explicitly where to break the value for use on each character of the display. This can be handled by simply assigning a sequence of strings thus:

from gpiozero import LEDCharDisplay, LEDMultiCharDisplay

c = LEDCharDisplay(4, 5, 6, 7, 8, 9, 10)
d = LEDMultiCharDisplay(c, 19, 20, 21, 22)
d.value = ('L.', 'E', 'D', 'S')

This is how the value will always be represented when queried (as a tuple of individual values) as it neatly handles dealing with heterogeneous types and the aforementioned decimal point issue.

Note

The value also controls whether a background thread is in use to multiplex the display. When all positions in the value are equal the background thread is disabled and all characters are simultaneously enabled.

LEDCharFont¶

class gpiozero.LEDCharFont(font)[source]¶

Contains a mapping of values to tuples of LED states.

This effectively acts as a “font” for LEDCharDisplay, and two default fonts (for 7-segment and 14-segment displays) are shipped with GPIO Zero by default. You can construct your own font instance from a dict which maps values (usually single-character strings) to a tuple of LED states:

from gpiozero import LEDCharDisplay, LEDCharFont

my_font = LEDCharFont({
    ' ': (0, 0, 0, 0, 0, 0, 0),
    'D': (1, 1, 1, 1, 1, 1, 0),
    'A': (1, 1, 1, 0, 1, 1, 1),
    'd': (0, 1, 1, 1, 1, 0, 1),
    'a': (1, 1, 1, 1, 1, 0, 1),
})
display = LEDCharDisplay(26, 13, 12, 22, 17, 19, 6, dp=5, font=my_font)
display.value = 'D'

Font instances are mutable and can be changed while actively in use by an instance of LEDCharDisplay. However, changing the font will not change the state of the LEDs in the display (though it may change the value of the display when next queried).

Note

Your custom mapping should always include a value (typically space) which represents all the LEDs off. This will usually be the default value for an instance of LEDCharDisplay.

You may also wish to load fonts from a friendly text-based format. A simple parser for such formats (supporting an arbitrary number of segments) is provided by gpiozero.fonts.load_segment_font().

ButtonBoard¶

class gpiozero.ButtonBoard(*pins, pull_up=True, active_state=None, bounce_time=None, hold_time=1, hold_repeat=False, pin_factory=None, **named_pins)[source]¶

Extends CompositeDevice and represents a generic button board or collection of buttons. The value of the button board is a tuple of all the buttons states. This can be used to control all the LEDs in a LEDBoard with a ButtonBoard:

from gpiozero import LEDBoard, ButtonBoard
from signal import pause

leds = LEDBoard(2, 3, 4, 5)
btns = ButtonBoard(6, 7, 8, 9)
leds.source = btns

pause()

Alternatively you could represent the number of pressed buttons with an LEDBarGraph:

from gpiozero import LEDBarGraph, ButtonBoard
from statistics import mean
from signal import pause

graph = LEDBarGraph(2, 3, 4, 5)
bb = ButtonBoard(6, 7, 8, 9)
graph.source = (mean(values) for values in bb.values)

pause()

Parameters:

*pins – Specify the GPIO pins that the buttons of the board are attached to. See Pin Numbering for valid pin numbers. You can designate as many pins as necessary.
pull_up (bool or None) – If True (the default), the GPIO pins will be pulled high by default. In this case, connect the other side of the buttons to ground. If False, the GPIO pins will be pulled low by default. In this case, connect the other side of the buttons to 3V3. If None, the pin will be floating, so it must be externally pulled up or down and the active_state parameter must be set accordingly.
active_state (bool or None) – See description under InputDevice for more information.
bounce_time (float) – If None (the default), no software bounce compensation will be performed. Otherwise, this is the length of time (in seconds) that the buttons will ignore changes in state after an initial change.
hold_time (float) – The length of time (in seconds) to wait after any button is pushed, until executing the when_held handler. Defaults to 1.
hold_repeat (bool) – If True, the when_held handler will be repeatedly executed as long as any buttons remain held, every hold_time seconds. If False (the default) the when_held handler will be only be executed once per hold.
pin_factory (Factory or None) – See API - Pins for more information (this is an advanced feature which most users can ignore).
**named_pins – Specify GPIO pins that buttons of the board are attached to, associating each button with a property name. You can designate as many pins as necessary and use any names, provided they’re not already in use by something else.

wait_for_press(timeout=None)¶

Pause the script until the device is activated, or the timeout is reached.

Parameters:	timeout (float or None) – Number of seconds to wait before proceeding. If this is `None` (the default), then wait indefinitely until the device is active.

wait_for_release(timeout=None)¶

Pause the script until the device is deactivated, or the timeout is reached.

Parameters:	timeout (float or None) – Number of seconds to wait before proceeding. If this is `None` (the default), then wait indefinitely until the device is inactive.

is_pressed¶: Composite devices are considered “active” if any of their constituent devices have a “truthy” value.

pressed_time¶: The length of time (in seconds) that the device has been active for. When the device is inactive, this is None.

value¶: A namedtuple() containing a value for each subordinate device. Devices with names will be represented as named elements. Unnamed devices will have a unique name generated for them, and they will appear in the position they appeared in the constructor.

when_pressed¶

The function to run when the device changes state from inactive to active.

This can be set to a function which accepts no (mandatory) parameters, or a Python function which accepts a single mandatory parameter (with as many optional parameters as you like). If the function accepts a single mandatory parameter, the device that activated it will be passed as that parameter.

Set this property to None (the default) to disable the event.

when_released¶

The function to run when the device changes state from active to inactive.

This can be set to a function which accepts no (mandatory) parameters, or a Python function which accepts a single mandatory parameter (with as many optional parameters as you like). If the function accepts a single mandatory parameter, the device that deactivated it will be passed as that parameter.

Set this property to None (the default) to disable the event.

TrafficLights¶

class gpiozero.TrafficLights(red, amber, green, *, yellow=None, pwm=False, initial_value=False, pin_factory=None)[source]¶

Extends LEDBoard for devices containing red, yellow, and green LEDs.

The following example initializes a device connected to GPIO pins 2, 3, and 4, then lights the amber (yellow) LED attached to GPIO 3:

from gpiozero import TrafficLights

traffic = TrafficLights(2, 3, 4)
traffic.amber.on()

Parameters:

red (int or str) – The GPIO pin that the red LED is attached to. See Pin Numbering for valid pin numbers.
amber (int or str or None) – The GPIO pin that the amber LED is attached to. See Pin Numbering for valid pin numbers.
yellow (int or str or None) – The GPIO pin that the yellow LED is attached to. This is merely an alias for the amber parameter; you can’t specify both amber and yellow. See Pin Numbering for valid pin numbers.
green (int or str) – The GPIO pin that the green LED is attached to. See Pin Numbering for valid pin numbers.
pwm (bool) – If True, construct PWMLED instances to represent each LED. If False (the default), construct regular LED instances.
initial_value (bool or None) – If False (the default), all LEDs will be off initially. If None, each device will be left in whatever state the pin is found in when configured for output (warning: this can be on). If True, the device will be switched on initially.
pin_factory (Factory or None) – See API - Pins for more information (this is an advanced feature which most users can ignore).

red¶: The red LED or PWMLED.

amber¶: The amber LED or PWMLED. Note that this attribute will not be present when the instance is constructed with the yellow keyword parameter.

yellow¶: The yellow LED or PWMLED. Note that this attribute will only be present when the instance is constructed with the yellow keyword parameter.

green¶: The green LED or PWMLED.

TrafficLightsBuzzer¶

class gpiozero.TrafficLightsBuzzer(lights, buzzer, button, *, pin_factory=None)[source]¶

Extends CompositeOutputDevice and is a generic class for HATs with traffic lights, a button and a buzzer.

Parameters:

lights (TrafficLights) – An instance of TrafficLights representing the traffic lights of the HAT.
buzzer (Buzzer) – An instance of Buzzer representing the buzzer on the HAT.
button (Button) – An instance of Button representing the button on the HAT.
pin_factory (Factory or None) – See API - Pins for more information (this is an advanced feature which most users can ignore).

lights¶: The TrafficLights instance passed as the lights parameter.

buzzer¶: The Buzzer instance passed as the buzzer parameter.

button¶: The Button instance passed as the button parameter.

PiHutXmasTree¶

class gpiozero.PiHutXmasTree(*, pwm=False, initial_value=False, pin_factory=None)[source]¶

Extends LEDBoard for The Pi Hut’s Xmas board: a 3D Christmas tree board with 24 red LEDs and a white LED as a star on top.

The 24 red LEDs can be accessed through the attributes led0, led1, led2, and so on. The white star LED is accessed through the star attribute. Alternatively, as with all descendents of LEDBoard, you can treat the instance as a sequence of LEDs (the first element is the star).

The Xmas Tree board pins are fixed and therefore there’s no need to specify them when constructing this class. The following example turns all the LEDs on one at a time:

from gpiozero import PiHutXmasTree
from time import sleep

tree = PiHutXmasTree()

for light in tree:
    light.on()
    sleep(1)

The following example turns the star LED on and sets all the red LEDs to flicker randomly:

from gpiozero import PiHutXmasTree
from gpiozero.tools import random_values
from signal import pause

tree = PiHutXmasTree(pwm=True)

tree.star.on()

for led in tree[1:]:
    led.source_delay = 0.1
    led.source = random_values()

pause()

Parameters:

pwm (bool) – If True, construct PWMLED instances for each pin. If False (the default), construct regular LED instances.
initial_value (bool or None) – If False (the default), all LEDs will be off initially. If None, each device will be left in whatever state the pin is found in when configured for output (warning: this can be on). If True, the device will be switched on initially.
pin_factory (Factory or None) – See API - Pins for more information (this is an advanced feature which most users can ignore).

star¶: Returns the LED or PWMLED representing the white star on top of the tree.

led0, led1, led2, ...: Returns the LED or PWMLED representing one of the red LEDs. There are actually 24 of these properties named led0, led1, and so on but for the sake of brevity we represent all 24 under this section.

LedBorg¶

class gpiozero.LedBorg(*, pwm=True, initial_value=(0, 0, 0), pin_factory=None)[source]¶

Extends RGBLED for the PiBorg LedBorg: an add-on board containing a very bright RGB LED.

The LedBorg pins are fixed and therefore there’s no need to specify them when constructing this class. The following example turns the LedBorg purple:

from gpiozero import LedBorg

led = LedBorg()
led.color = (1, 0, 1)

Parameters:

initial_value (Color or tuple) – The initial color for the LedBorg. Defaults to black (0, 0, 0).
pwm (bool) – If True (the default), construct PWMLED instances for each component of the LedBorg. If False, construct regular LED instances, which prevents smooth color graduations.
pin_factory (Factory or None) – See API - Pins for more information (this is an advanced feature which most users can ignore).

PiLiter¶

class gpiozero.PiLiter(*, pwm=False, initial_value=False, pin_factory=None)[source]¶

Extends LEDBoard for the Ciseco Pi-LITEr: a strip of 8 very bright LEDs.

The Pi-LITEr pins are fixed and therefore there’s no need to specify them when constructing this class. The following example turns on all the LEDs of the Pi-LITEr:

from gpiozero import PiLiter

lite = PiLiter()
lite.on()

Parameters:

pwm (bool) – If True, construct PWMLED instances for each pin. If False (the default), construct regular LED instances.
initial_value (bool or None) – If False (the default), all LEDs will be off initially. If None, each LED will be left in whatever state the pin is found in when configured for output (warning: this can be on). If True, the each LED will be switched on initially.
pin_factory (Factory or None) – See API - Pins for more information (this is an advanced feature which most users can ignore).

PiLiterBarGraph¶

class gpiozero.PiLiterBarGraph(*, pwm=False, initial_value=False, pin_factory=None)[source]¶

Extends LEDBarGraph to treat the Ciseco Pi-LITEr as an 8-segment bar graph.

The Pi-LITEr pins are fixed and therefore there’s no need to specify them when constructing this class. The following example sets the graph value to 0.5:

from gpiozero import PiLiterBarGraph

graph = PiLiterBarGraph()
graph.value = 0.5

Parameters:	pwm (bool) – If `True`, construct `PWMLED` instances for each pin. If `False` (the default), construct regular `LED` instances. initial_value (float) – The initial `value` of the graph given as a float between -1 and +1. Defaults to `0.0`. pin_factory (Factory or None) – See API - Pins for more information (this is an advanced feature which most users can ignore).

PiTraffic¶

class gpiozero.PiTraffic(*, pwm=False, initial_value=False, pin_factory=None)[source]¶

Extends TrafficLights for the Low Voltage Labs PI-TRAFFIC vertical traffic lights board when attached to GPIO pins 9, 10, and 11.

There’s no need to specify the pins if the PI-TRAFFIC is connected to the default pins (9, 10, 11). The following example turns on the amber LED on the PI-TRAFFIC:

from gpiozero import PiTraffic

traffic = PiTraffic()
traffic.amber.on()

To use the PI-TRAFFIC board when attached to a non-standard set of pins, simply use the parent class, TrafficLights.

Parameters:

pwm (bool) – If True, construct PWMLED instances to represent each LED. If False (the default), construct regular LED instances.
initial_value (bool) – If False (the default), all LEDs will be off initially. If None, each device will be left in whatever state the pin is found in when configured for output (warning: this can be on). If True, the device will be switched on initially.
pin_factory (Factory or None) – See API - Pins for more information (this is an advanced feature which most users can ignore).

PiStop¶

class gpiozero.PiStop(location, *, pwm=False, initial_value=False, pin_factory=None)[source]¶

Extends TrafficLights for the PiHardware Pi-Stop: a vertical traffic lights board.

The following example turns on the amber LED on a Pi-Stop connected to location A+:

from gpiozero import PiStop

traffic = PiStop('A+')
traffic.amber.on()

Parameters:

location (str) – The location on the GPIO header to which the Pi-Stop is connected. Must be one of: A, A+, B, B+, C, D.
pwm (bool) – If True, construct PWMLED instances to represent each LED. If False (the default), construct regular LED instances.
initial_value (bool) – If False (the default), all LEDs will be off initially. If None, each device will be left in whatever state the pin is found in when configured for output (warning: this can be on). If True, the device will be switched on initially.
pin_factory (Factory or None) – See API - Pins for more information (this is an advanced feature which most users can ignore).

FishDish¶

class gpiozero.FishDish(*, pwm=False, pin_factory=None)[source]¶

Extends CompositeOutputDevice for the Pi Supply FishDish: traffic light LEDs, a button and a buzzer.

The FishDish pins are fixed and therefore there’s no need to specify them when constructing this class. The following example waits for the button to be pressed on the FishDish, then turns on all the LEDs:

from gpiozero import FishDish

fish = FishDish()
fish.button.wait_for_press()
fish.lights.on()

Parameters:	pwm (bool) – If `True`, construct `PWMLED` instances to represent each LED. If `False` (the default), construct regular `LED` instances. pin_factory (Factory or None) – See API - Pins for more information (this is an advanced feature which most users can ignore).

TrafficHat¶

class gpiozero.TrafficHat(*, pwm=False, pin_factory=None)[source]¶

Extends CompositeOutputDevice for the Pi Supply Traffic HAT: a board with traffic light LEDs, a button and a buzzer.

The Traffic HAT pins are fixed and therefore there’s no need to specify them when constructing this class. The following example waits for the button to be pressed on the Traffic HAT, then turns on all the LEDs:

from gpiozero import TrafficHat

hat = TrafficHat()
hat.button.wait_for_press()
hat.lights.on()

Parameters:	pwm (bool) – If `True`, construct `PWMLED` instances to represent each LED. If `False` (the default), construct regular `LED` instances. pin_factory (Factory or None) – See API - Pins for more information (this is an advanced feature which most users can ignore).

TrafficpHat¶

class gpiozero.TrafficpHat(*, pwm=False, pin_factory=None)[source]¶

Extends TrafficLights for the Pi Supply Traffic pHAT: a small board with traffic light LEDs.

The Traffic pHAT pins are fixed and therefore there’s no need to specify them when constructing this class. The following example then turns on all the LEDs:

from gpiozero import TrafficpHat
phat = TrafficpHat()
phat.red.on()
phat.blink()

Parameters:

pwm (bool) – If True, construct PWMLED instances to represent each LED. If False (the default), construct regular LED instances.
initial_value (bool or None) – If False (the default), all LEDs will be off initially. If None, each device will be left in whatever state the pin is found in when configured for output (warning: this can be on). If True, the device will be switched on initially.
pin_factory (Factory or None) – See API - Pins for more information (this is an advanced feature which most users can ignore).

JamHat¶

class gpiozero.JamHat(*, pwm=False, pin_factory=None)[source]¶

Extends CompositeOutputDevice for the ModMyPi JamHat board.

There are 6 LEDs, two buttons and a tonal buzzer. The pins are fixed. Usage:

from gpiozero import JamHat

hat = JamHat()

hat.button_1.wait_for_press()
hat.lights_1.on()
hat.buzzer.play('C4')
hat.button_2.wait_for_press()
hat.off()

Parameters:	pwm (bool) – If `True`, construct `PWMLED` instances to represent each LED on the board. If `False` (the default), construct regular `LED` instances. pin_factory (Factory or None) – See API - Pins for more information (this is an advanced feature which most users can ignore).

lights_1, lights_2

Two LEDBoard instances representing the top (lights_1) and bottom (lights_2) rows of LEDs on the JamHat.

red, yellow, green: LED or PWMLED instances representing the red, yellow, and green LEDs along the top row.

button_1, button_2: The left (button_1) and right (button_2) Button objects on the JamHat.

buzzer¶: The TonalBuzzer at the bottom right of the JamHat.

off()[source]¶: Turns all the LEDs off and stops the buzzer.

on()[source]¶: Turns all the LEDs on and makes the buzzer play its mid tone.

Pibrella¶

class gpiozero.Pibrella(*, pwm=False, pin_factory=None)[source]¶

Extends CompositeOutputDevice for the Cyntech/Pimoroni Pibrella board.

The Pibrella board comprises 3 LEDs, a button, a tonal buzzer, four general purpose input channels, and four general purpose output channels (with LEDs).

This class exposes the LEDs, button and buzzer.

Usage:

from gpiozero import Pibrella

pb = Pibrella()

pb.button.wait_for_press()
pb.lights.on()
pb.buzzer.play('A4')
pb.off()

The four input and output channels are exposed so you can create GPIO Zero devices using these pins without looking up their respective pin numbers:

from gpiozero import Pibrella, LED, Button

pb = Pibrella()
btn = Button(pb.inputs.a, pull_up=False)
led = LED(pb.outputs.e)

btn.when_pressed = led.on

Parameters:	pwm (bool) – If `True`, construct `PWMLED` instances to represent each LED on the board, otherwise if `False` (the default), construct regular `LED` instances. pin_factory (Factory or None) – See API - Pins for more information (this is an advanced feature which most users can ignore).

lights¶

TrafficLights instance representing the three LEDs

red, amber, green: LED or PWMLED instances representing the red, amber, and green LEDs

button¶: The red Button object on the Pibrella

buzzer¶: A TonalBuzzer object representing the buzzer

inputs¶

A namedtuple() of the input pin numbers

a, b, c, d

outputs¶

A namedtuple() of the output pin numbers

e, f, g, h

off()[source]¶: Turns all the LEDs off and stops the buzzer.

on()[source]¶: Turns all the LEDs on and makes the buzzer play its mid tone.

Robot¶

class gpiozero.Robot(left, right, *, pwm=True, pin_factory=None)[source]¶

Extends CompositeDevice to represent a generic dual-motor robot.

This class is constructed with two tuples representing the forward and backward pins of the left and right controllers respectively. For example, if the left motor’s controller is connected to GPIOs 4 and 14, while the right motor’s controller is connected to GPIOs 17 and 18 then the following example will drive the robot forward:

from gpiozero import Robot

robot = Robot(left=(4, 14), right=(17, 18))
robot.forward()

Parameters:

left (tuple) – A tuple of two (or three) GPIO pins representing the forward and backward inputs of the left motor’s controller. Use three pins if your motor controller requires an enable pin.
right (tuple) – A tuple of two (or three) GPIO pins representing the forward and backward inputs of the right motor’s controller. Use three pins if your motor controller requires an enable pin.
pwm (bool) – If True (the default), construct PWMOutputDevice instances for the motor controller pins, allowing both direction and variable speed control. If False, construct DigitalOutputDevice instances, allowing only direction control.
pin_factory (Factory or None) – See API - Pins for more information (this is an advanced feature which most users can ignore).

left_motor¶: The Motor on the left of the robot.

right_motor¶: The Motor on the right of the robot.

backward(speed=1, **kwargs)[source]¶

Drive the robot backward by running both motors backward.

Parameters:

speed (float) – Speed at which to drive the motors, as a value between 0 (stopped) and 1 (full speed). The default is 1.
curve_left (float) – The amount to curve left while moving backwards, by driving the left motor at a slower speed. Maximum curve_left is 1, the default is 0 (no curve). This parameter can only be specified as a keyword parameter, and is mutually exclusive with curve_right.
curve_right (float) – The amount to curve right while moving backwards, by driving the right motor at a slower speed. Maximum curve_right is 1, the default is 0 (no curve). This parameter can only be specified as a keyword parameter, and is mutually exclusive with curve_left.

forward(speed=1, **kwargs)[source]¶

Drive the robot forward by running both motors forward.

Parameters:

speed (float) – Speed at which to drive the motors, as a value between 0 (stopped) and 1 (full speed). The default is 1.
curve_left (float) – The amount to curve left while moving forwards, by driving the left motor at a slower speed. Maximum curve_left is 1, the default is 0 (no curve). This parameter can only be specified as a keyword parameter, and is mutually exclusive with curve_right.
curve_right (float) – The amount to curve right while moving forwards, by driving the right motor at a slower speed. Maximum curve_right is 1, the default is 0 (no curve). This parameter can only be specified as a keyword parameter, and is mutually exclusive with curve_left.

left(speed=1)[source]¶

Make the robot turn left by running the right motor forward and left motor backward.

Parameters:	speed (float) – Speed at which to drive the motors, as a value between 0 (stopped) and 1 (full speed). The default is 1.

reverse()[source]¶: Reverse the robot’s current motor directions. If the robot is currently running full speed forward, it will run full speed backward. If the robot is turning left at half-speed, it will turn right at half-speed. If the robot is currently stopped it will remain stopped.

right(speed=1)[source]¶

Make the robot turn right by running the left motor forward and right motor backward.

Parameters:	speed (float) – Speed at which to drive the motors, as a value between 0 (stopped) and 1 (full speed). The default is 1.

stop()[source]¶: Stop the robot.

value¶: Represents the motion of the robot as a tuple of (left_motor_speed, right_motor_speed) with (-1, -1) representing full speed backwards, (1, 1) representing full speed forwards, and (0, 0) representing stopped.

PhaseEnableRobot¶

class gpiozero.PhaseEnableRobot(left, right, *, pwm=True, pin_factory=None)[source]¶

Extends CompositeDevice to represent a dual-motor robot based around a Phase/Enable motor board.

This class is constructed with two tuples representing the phase (direction) and enable (speed) pins of the left and right controllers respectively. For example, if the left motor’s controller is connected to GPIOs 12 and 5, while the right motor’s controller is connected to GPIOs 13 and 6 so the following example will drive the robot forward:

from gpiozero import PhaseEnableRobot

robot = PhaseEnableRobot(left=(5, 12), right=(6, 13))
robot.forward()

Parameters:

left (tuple) – A tuple of two GPIO pins representing the phase and enable inputs of the left motor’s controller.
right (tuple) – A tuple of two GPIO pins representing the phase and enable inputs of the right motor’s controller.
pwm (bool) – If True (the default), construct PWMOutputDevice instances for the motor controller’s enable pins, allowing both direction and variable speed control. If False, construct DigitalOutputDevice instances, allowing only direction control.
pin_factory (Factory or None) – See API - Pins for more information (this is an advanced feature which most users can ignore).

left_motor¶: The PhaseEnableMotor on the left of the robot.

right_motor¶: The PhaseEnableMotor on the right of the robot.

backward(speed=1)[source]¶

Drive the robot backward by running both motors backward.

Parameters:	speed (float) – Speed at which to drive the motors, as a value between 0 (stopped) and 1 (full speed). The default is 1.

forward(speed=1)[source]¶

Drive the robot forward by running both motors forward.

Parameters:	speed (float) – Speed at which to drive the motors, as a value between 0 (stopped) and 1 (full speed). The default is 1.

left(speed=1)[source]¶

Make the robot turn left by running the right motor forward and left motor backward.

Parameters:	speed (float) – Speed at which to drive the motors, as a value between 0 (stopped) and 1 (full speed). The default is 1.

reverse()[source]¶: Reverse the robot’s current motor directions. If the robot is currently running full speed forward, it will run full speed backward. If the robot is turning left at half-speed, it will turn right at half-speed. If the robot is currently stopped it will remain stopped.

right(speed=1)[source]¶

Make the robot turn right by running the left motor forward and right motor backward.

Parameters:	speed (float) – Speed at which to drive the motors, as a value between 0 (stopped) and 1 (full speed). The default is 1.

stop()[source]¶: Stop the robot.

value¶: Returns a tuple of two floating point values (-1 to 1) representing the speeds of the robot’s two motors (left and right). This property can also be set to alter the speed of both motors.

RyanteckRobot¶

class gpiozero.RyanteckRobot(*, pwm=True, pin_factory=None)[source]¶

Extends Robot for the Ryanteck motor controller board.

The Ryanteck MCB pins are fixed and therefore there’s no need to specify them when constructing this class. The following example drives the robot forward:

from gpiozero import RyanteckRobot

robot = RyanteckRobot()
robot.forward()

Parameters:	pwm (bool) – If `True` (the default), construct `PWMOutputDevice` instances for the motor controller pins, allowing both direction and variable speed control. If `False`, construct `DigitalOutputDevice` instances, allowing only direction control. pin_factory (Factory or None) – See API - Pins for more information (this is an advanced feature which most users can ignore).

CamJamKitRobot¶

class gpiozero.CamJamKitRobot(*, pwm=True, pin_factory=None)[source]¶

Extends Robot for the CamJam #3 EduKit motor controller board.

The CamJam robot controller pins are fixed and therefore there’s no need to specify them when constructing this class. The following example drives the robot forward:

from gpiozero import CamJamKitRobot

robot = CamJamKitRobot()
robot.forward()

Parameters:	pwm (bool) – If `True` (the default), construct `PWMOutputDevice` instances for the motor controller pins, allowing both direction and variable speed control. If `False`, construct `DigitalOutputDevice` instances, allowing only direction control. pin_factory (Factory or None) – See API - Pins for more information (this is an advanced feature which most users can ignore).

PololuDRV8835Robot¶

class gpiozero.PololuDRV8835Robot(*, pwm=True, pin_factory=None)[source]¶

Extends PhaseEnableRobot for the Pololu DRV8835 Dual Motor Driver Kit.

The Pololu DRV8835 pins are fixed and therefore there’s no need to specify them when constructing this class. The following example drives the robot forward:

from gpiozero import PololuDRV8835Robot

robot = PololuDRV8835Robot()
robot.forward()

Parameters:

pwm (bool) – If True (the default), construct PWMOutputDevice instances for the motor controller’s enable pins, allowing both direction and variable speed control. If False, construct DigitalOutputDevice instances, allowing only direction control.
pin_factory (Factory or None) – See API - Pins for more information (this is an advanced feature which most users can ignore).

Energenie¶

class gpiozero.Energenie(socket, *, initial_value=False, pin_factory=None)[source]¶

Extends Device to represent an Energenie socket controller.

This class is constructed with a socket number and an optional initial state (defaults to False, meaning off). Instances of this class can be used to switch peripherals on and off. For example:

from gpiozero import Energenie

lamp = Energenie(1)
lamp.on()

Parameters:

socket (int) – Which socket this instance should control. This is an integer number between 1 and 4.
initial_value (bool or None) – The initial state of the socket. As Energenie sockets provide no means of reading their state, you may provide an initial state for the socket, which will be set upon construction. This defaults to False which will switch the socket off. Specifying None will not set any initial state nor transmit any control signal to the device.
pin_factory (Factory or None) – See API - Pins for more information (this is an advanced feature which most users can ignore).

off()[source]¶: Turns the socket off.

on()[source]¶: Turns the socket on.

socket¶: Returns the socket number.

value¶: Returns True if the socket is on and False if the socket is off. Setting this property changes the state of the socket. Returns None only when constructed with initial_value set to None and neither on() nor off() have been called since construction.

StatusZero¶

class gpiozero.StatusZero(*labels, pwm=False, active_high=True, initial_value=False, pin_factory=None)[source]¶

Extends LEDBoard for The Pi Hut’s STATUS Zero: a Pi Zero sized add-on board with three sets of red/green LEDs to provide a status indicator.

The following example designates the first strip the label “wifi” and the second “raining”, and turns them green and red respectfully:

from gpiozero import StatusZero

status = StatusZero('wifi', 'raining')
status.wifi.green.on()
status.raining.red.on()

Each designated label will contain two LED objects named “red” and “green”.

Parameters:

*labels (str) – Specify the names of the labels you wish to designate the strips to. You can list up to three labels. If no labels are given, three strips will be initialised with names ‘one’, ‘two’, and ‘three’. If some, but not all strips are given labels, any remaining strips will not be initialised.
pin_factory (Factory or None) – See API - Pins for more information (this is an advanced feature which most users can ignore).

your-label-here, your-label-here, ...

This entry represents one of the three labelled attributes supported on the STATUS Zero board. It is an LEDBoard which contains:

red¶: The LED or PWMLED representing the red LED next to the label.

green¶: The LED or PWMLED representing the green LED next to the label.

StatusBoard¶

class gpiozero.StatusBoard(*labels, pwm=False, active_high=True, initial_value=False, pin_factory=None)[source]¶

Extends CompositeOutputDevice for The Pi Hut’s STATUS board: a HAT sized add-on board with five sets of red/green LEDs and buttons to provide a status indicator with additional input.

The following example designates the first strip the label “wifi” and the second “raining”, turns the wifi green and then activates the button to toggle its lights when pressed:

from gpiozero import StatusBoard

status = StatusBoard('wifi', 'raining')
status.wifi.lights.green.on()
status.wifi.button.when_pressed = status.wifi.lights.toggle

Each designated label will contain a “lights” LEDBoard containing two LED objects named “red” and “green”, and a Button object named “button”.

Parameters:

*labels (str) – Specify the names of the labels you wish to designate the strips to. You can list up to five labels. If no labels are given, five strips will be initialised with names ‘one’ to ‘five’. If some, but not all strips are given labels, any remaining strips will not be initialised.
pin_factory (Factory or None) – See API - Pins for more information (this is an advanced feature which most users can ignore).

your-label-here, your-label-here, ...

This entry represents one of the five labelled attributes supported on the STATUS board. It is an CompositeOutputDevice which contains:

lights¶

A LEDBoard representing the lights next to the label. It contains:

red¶: The LED or PWMLED representing the red LED next to the label.

green¶: The LED or PWMLED representing the green LED next to the label.

button¶: A Button representing the button next to the label.

SnowPi¶

class gpiozero.SnowPi(*, pwm=False, initial_value=False, pin_factory=None)[source]¶

Extends LEDBoard for the Ryanteck SnowPi board.

The SnowPi pins are fixed and therefore there’s no need to specify them when constructing this class. The following example turns on the eyes, sets the nose pulsing, and the arms blinking:

from gpiozero import SnowPi

snowman = SnowPi(pwm=True)
snowman.eyes.on()
snowman.nose.pulse()
snowman.arms.blink()

Parameters:

pwm (bool) – If True, construct PWMLED instances to represent each LED. If False (the default), construct regular LED instances.
initial_value (bool) – If False (the default), all LEDs will be off initially. If None, each device will be left in whatever state the pin is found in when configured for output (warning: this can be on). If True, the device will be switched on initially.
pin_factory (Factory or None) – See API - Pins for more information (this is an advanced feature which most users can ignore).

arms¶

A LEDBoard representing the arms of the snow man. It contains the following attributes:

left, right

Two LEDBoard objects representing the left and right arms of the snow-man. They contain:

top, middle, bottom: The LED or PWMLED down the snow-man’s arms.

eyes¶

A LEDBoard representing the eyes of the snow-man. It contains:

left, right: The LED or PWMLED for the snow-man’s eyes.

nose¶: The LED or PWMLED for the snow-man’s nose.

PumpkinPi¶

class gpiozero.PumpkinPi(*, pwm=False, initial_value=False, pin_factory=None)[source]¶

Extends LEDBoard for the ModMyPi PumpkinPi board.

There are twelve LEDs connected up to individual pins, so for the PumpkinPi the pins are fixed. For example:

from gpiozero import PumpkinPi

pumpkin = PumpkinPi(pwm=True)
pumpkin.sides.pulse()
pumpkin.off()

Parameters:

pwm (bool) – If True, construct PWMLED instances to represent each LED. If False (the default), construct regular LED instances
initial_value (bool or None) – If False (the default), all LEDs will be off initially. If None, each device will be left in whatever state the pin is found in when configured for output (warning: this can be on). If True, the device will be switched on initially.
pin_factory (Factory or None) – See API - Pins for more information (this is an advanced feature which most users can ignore).

sides¶

A LEDBoard representing the LEDs around the edge of the pumpkin. It contains:

left, right

Two LEDBoard instances representing the LEDs on the left and right sides of the pumpkin. They each contain:

top, midtop, middle, midbottom, bottom: Each LED or PWMLED around the specified side of the pumpkin.

eyes¶

A LEDBoard representing the eyes of the pumpkin. It contains:

left, right: The LED or PWMLED for each of the pumpkin’s eyes.

Base Classes¶

The classes in the sections above are derived from a series of base classes, some of which are effectively abstract. The classes form the (partial) hierarchy displayed in the graph below:

For composite devices, the following chart shows which devices are composed of which other devices:

The following sections document these base classes for advanced users that wish to construct classes for their own devices.

LEDCollection¶

class gpiozero.LEDCollection(*pins, pwm=False, active_high=True, initial_value=False, pin_factory=None, **named_pins)[source]¶

Extends CompositeOutputDevice. Abstract base class for LEDBoard and LEDBarGraph.

is_lit¶: Composite devices are considered “active” if any of their constituent devices have a “truthy” value.

leds¶: A flat tuple of all LEDs contained in this collection (and all sub-collections).

CompositeOutputDevice¶

class gpiozero.CompositeOutputDevice(*args, _order=None, pin_factory=None, **kwargs)[source]¶

Extends CompositeDevice with on(), off(), and toggle() methods for controlling subordinate output devices. Also extends value to be writeable.

Parameters:

*args (Device) – The un-named devices that belong to the composite device. The value attributes of these devices will be represented within the composite device’s tuple value in the order specified here.
_order (list or None) – If specified, this is the order of named items specified by keyword arguments (to ensure that the value tuple is constructed with a specific order). All keyword arguments must be included in the collection. If omitted, an alphabetically sorted order will be selected for keyword arguments.
pin_factory (Factory or None) – See API - Pins for more information (this is an advanced feature which most users can ignore).
**kwargs (Device) – The named devices that belong to the composite device. These devices will be accessible as named attributes on the resulting device, and their value attributes will be accessible as named elements of the composite device’s tuple value.

off()[source]¶: Turn all the output devices off.

on()[source]¶: Turn all the output devices on.

toggle()[source]¶: Toggle all the output devices. For each device, if it’s on, turn it off; if it’s off, turn it on.

value¶: A tuple containing a value for each subordinate device. This property can also be set to update the state of all subordinate output devices.

CompositeDevice¶

class gpiozero.CompositeDevice(*args, _order=None, pin_factory=None, **kwargs)[source]¶

Extends Device. Represents a device composed of multiple devices like simple HATs, H-bridge motor controllers, robots composed of multiple motors, etc.

The constructor accepts subordinate devices as positional or keyword arguments. Positional arguments form unnamed devices accessed by treating the composite device as a container, while keyword arguments are added to the device as named (read-only) attributes.

For example:

>>> from gpiozero import *
>>> d = CompositeDevice(LED(2), LED(3), LED(4), btn=Button(17))
>>> d[0]
<gpiozero.LED object on pin GPIO2, active_high=True, is_active=False>
>>> d[1]
<gpiozero.LED object on pin GPIO3, active_high=True, is_active=False>
>>> d[2]
<gpiozero.LED object on pin GPIO4, active_high=True, is_active=False>
>>> d.btn
<gpiozero.Button object on pin GPIO17, pull_up=True, is_active=False>
>>> d.value
CompositeDeviceValue(device_0=False, device_1=False, device_2=False, btn=False)

Parameters:

*args (Device) – The un-named devices that belong to the composite device. The value attributes of these devices will be represented within the composite device’s tuple value in the order specified here.
_order (list or None) – If specified, this is the order of named items specified by keyword arguments (to ensure that the value tuple is constructed with a specific order). All keyword arguments must be included in the collection. If omitted, an alphabetically sorted order will be selected for keyword arguments.
pin_factory (Factory or None) – See API - Pins for more information (this is an advanced feature which most users can ignore).
**kwargs (Device) – The named devices that belong to the composite device. These devices will be accessible as named attributes on the resulting device, and their value attributes will be accessible as named elements of the composite device’s tuple value.

close()[source]¶

Shut down the device and release all associated resources (such as GPIO pins).

This method is idempotent (can be called on an already closed device without any side-effects). It is primarily intended for interactive use at the command line. It disables the device and releases its pin(s) for use by another device.

You can attempt to do this simply by deleting an object, but unless you’ve cleaned up all references to the object this may not work (even if you’ve cleaned up all references, there’s still no guarantee the garbage collector will actually delete the object at that point). By contrast, the close method provides a means of ensuring that the object is shut down.

For example, if you have a breadboard with a buzzer connected to pin 16, but then wish to attach an LED instead:

>>> from gpiozero import *
>>> bz = Buzzer(16)
>>> bz.on()
>>> bz.off()
>>> bz.close()
>>> led = LED(16)
>>> led.blink()

Device descendents can also be used as context managers using the with statement. For example:

>>> from gpiozero import *
>>> with Buzzer(16) as bz:
...     bz.on()
...
>>> with LED(16) as led:
...     led.on()
...

closed¶: Returns True if the device is closed (see the close() method). Once a device is closed you can no longer use any other methods or properties to control or query the device.

is_active¶: Composite devices are considered “active” if any of their constituent devices have a “truthy” value.

namedtuple¶: The namedtuple() type constructed to represent the value of the composite device. The value attribute returns values of this type.

value¶: A namedtuple() containing a value for each subordinate device. Devices with names will be represented as named elements. Unnamed devices will have a unique name generated for them, and they will appear in the position they appeared in the constructor.

API - Internal Devices¶

GPIO Zero also provides several “internal” devices which represent facilities provided by the operating system itself. These can be used to react to things like the time of day, or whether a server is available on the network.

These devices provide an API similar to and compatible with GPIO devices so that internal device events can trigger changes to GPIO output devices the way input devices can. In the same way a Button object is active when it’s pressed, and can be used to trigger other devices when its state changes, a TimeOfDay object is active during a particular time period.

Consider the following code in which a Button object is used to control an LED object:

from gpiozero import LED, Button
from signal import pause

led = LED(2)
btn = Button(3)

btn.when_pressed = led.on
btn.when_released = led.off

pause()

Now consider the following example in which a TimeOfDay object is used to control an LED using the same method:

from gpiozero import LED, TimeOfDay
from datetime import time
from signal import pause

led = LED(2)
tod = TimeOfDay(time(9), time(10))

tod.when_activated = led.on
tod.when_deactivated = led.off

pause()

Here, rather than the LED being controlled by the press of a button, it’s controlled by the time. When the time reaches 09:00AM, the LED comes on, and at 10:00AM it goes off.

Like the Button object, internal devices like the TimeOfDay object has value, values, is_active, when_activated and when_deactivated attributes, so alternative methods using the other paradigms would also work.

Note

Note that although the constructor parameter pin_factory is available for internal devices, and is required to be valid, the pin factory chosen will not make any practical difference. Reading a remote Pi’s CPU temperature, for example, is not currently possible.

Regular Classes¶

The following classes are intended for general use with the devices they are named after. All classes in this section are concrete (not abstract).

TimeOfDay¶

class gpiozero.TimeOfDay(start_time, end_time, *, utc=True, event_delay=10.0, pin_factory=None)[source]¶

Extends PolledInternalDevice to provide a device which is active when the computer’s clock indicates that the current time is between start_time and end_time (inclusive) which are time instances.

The following example turns on a lamp attached to an Energenie plug between 07:00AM and 08:00AM:

from gpiozero import TimeOfDay, Energenie
from datetime import time
from signal import pause

lamp = Energenie(1)
morning = TimeOfDay(time(7), time(8))

morning.when_activated = lamp.on
morning.when_deactivated = lamp.off

pause()

Note that start_time may be greater than end_time, indicating a time period which crosses midnight.

Parameters:

start_time (time) – The time from which the device will be considered active.
end_time (time) – The time after which the device will be considered inactive.
utc (bool) – If True (the default), a naive UTC time will be used for the comparison rather than a local time-zone reading.
event_delay (float) – The number of seconds between file reads (defaults to 10 seconds).
pin_factory (Factory or None) – See API - Pins for more information (this is an advanced feature which most users can ignore).

end_time¶: The time of day after which the device will be considered inactive.

is_active¶: Returns True if the device is currently active and False otherwise. This property is usually derived from value. Unlike value, this is always a boolean.

start_time¶: The time of day after which the device will be considered active.

utc¶: If True, use a naive UTC time reading for comparison instead of a local timezone reading.

value¶: Returns 1 when the system clock reads between start_time and end_time, and 0 otherwise. If start_time is greater than end_time (indicating a period that crosses midnight), then this returns 1 when the current time is greater than start_time or less than end_time.

when_activated¶

The function to run when the device changes state from inactive to active (time reaches start_time).

This can be set to a function which accepts no (mandatory) parameters, or a Python function which accepts a single mandatory parameter (with as many optional parameters as you like). If the function accepts a single mandatory parameter, the device that activated it will be passed as that parameter.

Set this property to None (the default) to disable the event.

when_deactivated¶

The function to run when the device changes state from active to inactive (time reaches end_time).

This can be set to a function which accepts no (mandatory) parameters, or a Python function which accepts a single mandatory parameter (with as many optional parameters as you like). If the function accepts a single mandatory parameter, the device that activated it will be passed as that parameter.

Set this property to None (the default) to disable the event.

PingServer¶

class gpiozero.PingServer(host, *, event_delay=10.0, pin_factory=None)[source]¶

Extends PolledInternalDevice to provide a device which is active when a host (domain name or IP address) can be pinged.

The following example lights an LED while google.com is reachable:

from gpiozero import PingServer, LED
from signal import pause

google = PingServer('google.com')
led = LED(4)

google.when_activated = led.on
google.when_deactivated = led.off

pause()

Parameters:	host (str) – The hostname or IP address to attempt to ping. event_delay (float) – The number of seconds between pings (defaults to 10 seconds). pin_factory (Factory or None) – See API - Pins for more information (this is an advanced feature which most users can ignore).

host¶: The hostname or IP address to test whenever value is queried.

is_active¶: Returns True if the device is currently active and False otherwise. This property is usually derived from value. Unlike value, this is always a boolean.

value¶: Returns 1 if the host returned a single ping, and 0 otherwise.

when_activated¶

The function to run when the device changes state from inactive (host unresponsive) to active (host responsive).

This can be set to a function which accepts no (mandatory) parameters, or a Python function which accepts a single mandatory parameter (with as many optional parameters as you like). If the function accepts a single mandatory parameter, the device that activated it will be passed as that parameter.

Set this property to None (the default) to disable the event.

when_deactivated¶

The function to run when the device changes state from inactive (host responsive) to active (host unresponsive).

This can be set to a function which accepts no (mandatory) parameters, or a Python function which accepts a single mandatory parameter (with as many optional parameters as you like). If the function accepts a single mandatory parameter, the device that activated it will be passed as that parameter.

Set this property to None (the default) to disable the event.

CPUTemperature¶

class gpiozero.CPUTemperature(sensor_file='/sys/class/thermal/thermal_zone0/temp', *, min_temp=0.0, max_temp=100.0, threshold=80.0, event_delay=5.0, pin_factory=None)[source]¶

Extends PolledInternalDevice to provide a device which is active when the CPU temperature exceeds the threshold value.

The following example plots the CPU’s temperature on an LED bar graph:

from gpiozero import LEDBarGraph, CPUTemperature
from signal import pause

# Use minimums and maximums that are closer to "normal" usage so the
# bar graph is a bit more "lively"
cpu = CPUTemperature(min_temp=50, max_temp=90)

print('Initial temperature: {}C'.format(cpu.temperature))

graph = LEDBarGraph(5, 6, 13, 19, 25, pwm=True)
graph.source = cpu

pause()

Parameters:

sensor_file (str) – The file from which to read the temperature. This defaults to the sysfs file /sys/class/thermal/thermal_zone0/temp. Whatever file is specified is expected to contain a single line containing the temperature in milli-degrees celsius.
min_temp (float) – The temperature at which value will read 0.0. This defaults to 0.0.
max_temp (float) – The temperature at which value will read 1.0. This defaults to 100.0.
threshold (float) – The temperature above which the device will be considered “active”. (see is_active). This defaults to 80.0.
event_delay (float) – The number of seconds between file reads (defaults to 5 seconds).
pin_factory (Factory or None) – See API - Pins for more information (this is an advanced feature which most users can ignore).

is_active¶: Returns True when the CPU temperature exceeds the threshold.

temperature¶: Returns the current CPU temperature in degrees celsius.

value¶: Returns the current CPU temperature as a value between 0.0 (representing the min_temp value) and 1.0 (representing the max_temp value). These default to 0.0 and 100.0 respectively, hence value is temperature divided by 100 by default.

when_activated¶

The function to run when the device changes state from inactive to active (temperature reaches threshold).

This can be set to a function which accepts no (mandatory) parameters, or a Python function which accepts a single mandatory parameter (with as many optional parameters as you like). If the function accepts a single mandatory parameter, the device that activated it will be passed as that parameter.

Set this property to None (the default) to disable the event.

when_deactivated¶

The function to run when the device changes state from active to inactive (temperature drops below threshold).

This can be set to a function which accepts no (mandatory) parameters, or a Python function which accepts a single mandatory parameter (with as many optional parameters as you like). If the function accepts a single mandatory parameter, the device that activated it will be passed as that parameter.

Set this property to None (the default) to disable the event.

LoadAverage¶

class gpiozero.LoadAverage(load_average_file='/proc/loadavg', *, min_load_average=0.0, max_load_average=1.0, threshold=0.8, minutes=5, event_delay=10.0, pin_factory=None)[source]¶

Extends PolledInternalDevice to provide a device which is active when the CPU load average exceeds the threshold value.

The following example plots the load average on an LED bar graph:

from gpiozero import LEDBarGraph, LoadAverage
from signal import pause

la = LoadAverage(min_load_average=0, max_load_average=2)
graph = LEDBarGraph(5, 6, 13, 19, 25, pwm=True)

graph.source = la

pause()

Parameters:

load_average_file (str) – The file from which to read the load average. This defaults to the proc file /proc/loadavg. Whatever file is specified is expected to contain three space-separated load averages at the beginning of the file, representing 1 minute, 5 minute and 15 minute averages respectively.
min_load_average (float) – The load average at which value will read 0.0. This defaults to 0.0.
max_load_average (float) – The load average at which value will read 1.0. This defaults to 1.0.
threshold (float) – The load average above which the device will be considered “active”. (see is_active). This defaults to 0.8.
minutes (int) – The number of minutes over which to average the load. Must be 1, 5 or 15. This defaults to 5.
event_delay (float) – The number of seconds between file reads (defaults to 10 seconds).
pin_factory (Factory or None) – See API - Pins for more information (this is an advanced feature which most users can ignore).

is_active¶: Returns True when the load_average exceeds the threshold.

load_average¶: Returns the current load average.

value¶: Returns the current load average as a value between 0.0 (representing the min_load_average value) and 1.0 (representing the max_load_average value). These default to 0.0 and 1.0 respectively.

when_activated¶

The function to run when the device changes state from inactive to active (load average reaches threshold).

This can be set to a function which accepts no (mandatory) parameters, or a Python function which accepts a single mandatory parameter (with as many optional parameters as you like). If the function accepts a single mandatory parameter, the device that activated it will be passed as that parameter.

Set this property to None (the default) to disable the event.

when_deactivated¶

The function to run when the device changes state from active to inactive (load average drops below threshold).

This can be set to a function which accepts no (mandatory) parameters, or a Python function which accepts a single mandatory parameter (with as many optional parameters as you like). If the function accepts a single mandatory parameter, the device that activated it will be passed as that parameter.

Set this property to None (the default) to disable the event.

DiskUsage¶

class gpiozero.DiskUsage(filesystem='/', *, threshold=90.0, event_delay=30.0, pin_factory=None)[source]¶

Extends PolledInternalDevice to provide a device which is active when the disk space used exceeds the threshold value.

The following example plots the disk usage on an LED bar graph:

from gpiozero import LEDBarGraph, DiskUsage
from signal import pause

disk = DiskUsage()

print('Current disk usage: {}%'.format(disk.usage))

graph = LEDBarGraph(5, 6, 13, 19, 25, pwm=True)
graph.source = disk

pause()

Parameters:

filesystem (str) – A path within the filesystem for which the disk usage needs to be computed. This defaults to /, which is the root filesystem.
threshold (float) – The disk usage percentage above which the device will be considered “active” (see is_active). This defaults to 90.0.
event_delay (float) – The number of seconds between file reads (defaults to 30 seconds).
pin_factory (Factory or None) – See API - Pins for more information (this is an advanced feature which most users can ignore).

is_active¶: Returns True when the disk usage exceeds the threshold.

usage¶: Returns the current disk usage in percentage.

value¶: Returns the current disk usage as a value between 0.0 and 1.0 by dividing usage by 100.

when_activated¶

The function to run when the device changes state from inactive to active (disk usage reaches threshold).

This can be set to a function which accepts no (mandatory) parameters, or a Python function which accepts a single mandatory parameter (with as many optional parameters as you like). If the function accepts a single mandatory parameter, the device that activated it will be passed as that parameter.

Set this property to None (the default) to disable the event.

when_deactivated¶

The function to run when the device changes state from active to inactive (disk usage drops below threshold).

This can be set to a function which accepts no (mandatory) parameters, or a Python function which accepts a single mandatory parameter (with as many optional parameters as you like). If the function accepts a single mandatory parameter, the device that activated it will be passed as that parameter.

Set this property to None (the default) to disable the event.

Base Classes¶

The classes in the sections above are derived from a series of base classes, some of which are effectively abstract. The classes form the (partial) hierarchy displayed in the graph below (abstract classes are shaded lighter than concrete classes):

The following sections document these base classes for advanced users that wish to construct classes for their own devices.

PolledInternalDevice¶

class gpiozero.PolledInternalDevice(*, event_delay=1.0, pin_factory=None)[source]¶: Extends InternalDevice to provide a background thread to poll internal devices that lack any other mechanism to inform the instance of changes.

InternalDevice¶

class gpiozero.InternalDevice(*, pin_factory=None)[source]¶: Extends Device to provide a basis for devices which have no specific hardware representation. These are effectively pseudo-devices and usually represent operating system services like the internal clock, file systems or network facilities.

API - Generic Classes¶

The GPIO Zero class hierarchy is quite extensive. It contains several base classes (most of which are documented in their corresponding chapters):

Device is the root of the hierarchy, implementing base functionality like close() and context manager handlers.
GPIODevice represents individual devices that attach to a single GPIO pin
SPIDevice represents devices that communicate over an SPI interface (implemented as four GPIO pins)
InternalDevice represents devices that are entirely internal to the Pi (usually operating system related services)
CompositeDevice represents devices composed of multiple other devices like HATs

There are also several mixin classes for adding important functionality at numerous points in the hierarchy, which is illustrated below (mixin classes are represented in purple, while abstract classes are shaded lighter):

Device¶

class gpiozero.Device(*, pin_factory=None)[source]¶

Represents a single device of any type; GPIO-based, SPI-based, I2C-based, etc. This is the base class of the device hierarchy. It defines the basic services applicable to all devices (specifically the is_active property, the value property, and the close() method).

pin_factory¶

This attribute exists at both a class level (representing the default pin factory used to construct devices when no pin_factory parameter is specified), and at an instance level (representing the pin factory that the device was constructed with).

The pin factory provides various facilities to the device including allocating pins, providing low level interfaces (e.g. SPI), and clock facilities (querying and calculating elapsed times).

close()¶

Shut down the device and release all associated resources (such as GPIO pins).

This method is idempotent (can be called on an already closed device without any side-effects). It is primarily intended for interactive use at the command line. It disables the device and releases its pin(s) for use by another device.

You can attempt to do this simply by deleting an object, but unless you’ve cleaned up all references to the object this may not work (even if you’ve cleaned up all references, there’s still no guarantee the garbage collector will actually delete the object at that point). By contrast, the close method provides a means of ensuring that the object is shut down.

For example, if you have a breadboard with a buzzer connected to pin 16, but then wish to attach an LED instead:

>>> from gpiozero import *
>>> bz = Buzzer(16)
>>> bz.on()
>>> bz.off()
>>> bz.close()
>>> led = LED(16)
>>> led.blink()

Device descendents can also be used as context managers using the with statement. For example:

>>> from gpiozero import *
>>> with Buzzer(16) as bz:
...     bz.on()
...
>>> with LED(16) as led:
...     led.on()
...

closed¶: Returns True if the device is closed (see the close() method). Once a device is closed you can no longer use any other methods or properties to control or query the device.

is_active¶: Returns True if the device is currently active and False otherwise. This property is usually derived from value. Unlike value, this is always a boolean.

value¶: Returns a value representing the device’s state. Frequently, this is a boolean value, or a number between 0 and 1 but some devices use larger ranges (e.g. -1 to +1) and composite devices usually use tuples to return the states of all their subordinate components.

ValuesMixin¶

class gpiozero.ValuesMixin(...)[source]¶

Adds a values property to the class which returns an infinite generator of readings from the value property. There is rarely a need to use this mixin directly as all base classes in GPIO Zero include it.

Note

Use this mixin first in the parent class list.

values¶: An infinite iterator of values read from value.

SourceMixin¶

class gpiozero.SourceMixin(...)[source]¶

Adds a source property to the class which, given an iterable or a ValuesMixin descendent, sets value to each member of that iterable until it is exhausted. This mixin is generally included in novel output devices to allow their state to be driven from another device.

Note

Use this mixin first in the parent class list.

source¶: The iterable to use as a source of values for value.

source_delay¶: The delay (measured in seconds) in the loop used to read values from source. Defaults to 0.01 seconds which is generally sufficient to keep CPU usage to a minimum while providing adequate responsiveness.

SharedMixin¶

class gpiozero.SharedMixin(...)[source]¶

This mixin marks a class as “shared”. In this case, the meta-class (GPIOMeta) will use _shared_key() to convert the constructor arguments to an immutable key, and will check whether any existing instances match that key. If they do, they will be returned by the constructor instead of a new instance. An internal reference counter is used to determine how many times an instance has been “constructed” in this way.

When close() is called, an internal reference counter will be decremented and the instance will only close when it reaches zero.

classmethod _shared_key(*args, **kwargs)[source]¶

This is called with the constructor arguments to generate a unique key (which must be storable in a dict and, thus, immutable and hashable) representing the instance that can be shared. This must be overridden by descendents.

The default simply assumes all positional arguments are immutable and returns this as the key but this is almost never the “right” thing to do and almost all descendents should override this method.

EventsMixin¶

class gpiozero.EventsMixin(...)[source]¶

Adds edge-detected when_activated() and when_deactivated() events to a device based on changes to the is_active property common to all devices. Also adds wait_for_active() and wait_for_inactive() methods for level-waiting.

Note

Note that this mixin provides no means of actually firing its events; call _fire_events() in sub-classes when device state changes to trigger the events. This should also be called once at the end of initialization to set initial states.

wait_for_active(timeout=None)[source]¶

Pause the script until the device is activated, or the timeout is reached.

Parameters:	timeout (float or None) – Number of seconds to wait before proceeding. If this is `None` (the default), then wait indefinitely until the device is active.

wait_for_inactive(timeout=None)[source]¶

Pause the script until the device is deactivated, or the timeout is reached.

Parameters:	timeout (float or None) – Number of seconds to wait before proceeding. If this is `None` (the default), then wait indefinitely until the device is inactive.

active_time¶: The length of time (in seconds) that the device has been active for. When the device is inactive, this is None.

inactive_time¶: The length of time (in seconds) that the device has been inactive for. When the device is active, this is None.

when_activated¶

The function to run when the device changes state from inactive to active.

This can be set to a function which accepts no (mandatory) parameters, or a Python function which accepts a single mandatory parameter (with as many optional parameters as you like). If the function accepts a single mandatory parameter, the device that activated it will be passed as that parameter.

Set this property to None (the default) to disable the event.

when_deactivated¶

The function to run when the device changes state from active to inactive.

This can be set to a function which accepts no (mandatory) parameters, or a Python function which accepts a single mandatory parameter (with as many optional parameters as you like). If the function accepts a single mandatory parameter, the device that deactivated it will be passed as that parameter.

Set this property to None (the default) to disable the event.

HoldMixin¶

class gpiozero.HoldMixin(...)[source]¶

Extends EventsMixin to add the when_held event and the machinery to fire that event repeatedly (when hold_repeat is True) at internals defined by hold_time.

held_time¶: The length of time (in seconds) that the device has been held for. This is counted from the first execution of the when_held event rather than when the device activated, in contrast to active_time. If the device is not currently held, this is None.

hold_repeat¶: If True, when_held will be executed repeatedly with hold_time seconds between each invocation.

hold_time¶: The length of time (in seconds) to wait after the device is activated, until executing the when_held handler. If hold_repeat is True, this is also the length of time between invocations of when_held.

is_held¶: When True, the device has been active for at least hold_time seconds.

when_held¶

The function to run when the device has remained active for hold_time seconds.

This can be set to a function which accepts no (mandatory) parameters, or a Python function which accepts a single mandatory parameter (with as many optional parameters as you like). If the function accepts a single mandatory parameter, the device that activated will be passed as that parameter.

Set this property to None (the default) to disable the event.

API - Device Source Tools¶

GPIO Zero includes several utility routines which are intended to be used with the Source/Values attributes common to most devices in the library. These utility routines are in the tools module of GPIO Zero and are typically imported as follows:

from gpiozero.tools import scaled, negated, all_values

Given that source and values deal with infinite iterators, another excellent source of utilities is the itertools module in the standard library.

Single source conversions¶

gpiozero.tools.absoluted(values)[source]¶

Returns values with all negative elements negated (so that they’re positive). For example:

from gpiozero import PWMLED, Motor, MCP3008
from gpiozero.tools import absoluted, scaled
from signal import pause

led = PWMLED(4)
motor = Motor(22, 27)
pot = MCP3008(channel=0)

motor.source = scaled(pot, -1, 1)
led.source = absoluted(motor)

pause()

gpiozero.tools.booleanized(values, min_value, max_value, hysteresis=0)[source]¶

Returns True for each item in values between min_value and max_value, and False otherwise. hysteresis can optionally be used to add hysteresis which prevents the output value rapidly flipping when the input value is fluctuating near the min_value or max_value thresholds. For example, to light an LED only when a potentiometer is between ¼ and ¾ of its full range:

from gpiozero import LED, MCP3008
from gpiozero.tools import booleanized
from signal import pause

led = LED(4)
pot = MCP3008(channel=0)

led.source = booleanized(pot, 0.25, 0.75)

pause()

gpiozero.tools.clamped(values, output_min=0, output_max=1)[source]¶

Returns values clamped from output_min to output_max, i.e. any items less than output_min will be returned as output_min and any items larger than output_max will be returned as output_max (these default to 0 and 1 respectively). For example:

from gpiozero import PWMLED, MCP3008
from gpiozero.tools import clamped
from signal import pause

led = PWMLED(4)
pot = MCP3008(channel=0)

led.source = clamped(pot, 0.5, 1.0)

pause()

gpiozero.tools.inverted(values, input_min=0, input_max=1)[source]¶

Returns the inversion of the supplied values (input_min becomes input_max, input_max becomes input_min, input_min + 0.1 becomes input_max - 0.1, etc.). All items in values are assumed to be between input_min and input_max (which default to 0 and 1 respectively), and the output will be in the same range. For example:

from gpiozero import MCP3008, PWMLED
from gpiozero.tools import inverted
from signal import pause

led = PWMLED(4)
pot = MCP3008(channel=0)

led.source = inverted(pot)

pause()

gpiozero.tools.negated(values)[source]¶

Returns the negation of the supplied values (True becomes False, and False becomes True). For example:

from gpiozero import Button, LED
from gpiozero.tools import negated
from signal import pause

led = LED(4)
btn = Button(17)

led.source = negated(btn)

pause()

gpiozero.tools.post_delayed(values, delay)[source]¶: Waits for delay seconds after returning each item from values.

gpiozero.tools.post_periodic_filtered(values, repeat_after, block)[source]¶

After every repeat_after items, blocks the next block items from values. Note that unlike pre_periodic_filtered(), repeat_after can’t be 0. For example, to block every tenth item read from an ADC:

from gpiozero import MCP3008
from gpiozero.tools import post_periodic_filtered

adc = MCP3008(channel=0)

for value in post_periodic_filtered(adc, 9, 1):
    print(value)

gpiozero.tools.pre_delayed(values, delay)[source]¶: Waits for delay seconds before returning each item from values.

gpiozero.tools.pre_periodic_filtered(values, block, repeat_after)[source]¶

Blocks the first block items from values, repeating the block after every repeat_after items, if repeat_after is non-zero. For example, to discard the first 50 values read from an ADC:

from gpiozero import MCP3008
from gpiozero.tools import pre_periodic_filtered

adc = MCP3008(channel=0)

for value in pre_periodic_filtered(adc, 50, 0):
    print(value)

Or to only display every even item read from an ADC:

from gpiozero import MCP3008
from gpiozero.tools import pre_periodic_filtered

adc = MCP3008(channel=0)

for value in pre_periodic_filtered(adc, 1, 1):
    print(value)

gpiozero.tools.quantized(values, steps, input_min=0, input_max=1)[source]¶

Returns values quantized to steps increments. All items in values are assumed to be between input_min and input_max (which default to 0 and 1 respectively), and the output will be in the same range.

For example, to quantize values between 0 and 1 to 5 “steps” (0.0, 0.25, 0.5, 0.75, 1.0):

from gpiozero import PWMLED, MCP3008
from gpiozero.tools import quantized
from signal import pause

led = PWMLED(4)
pot = MCP3008(channel=0)

led.source = quantized(pot, 4)

pause()

gpiozero.tools.queued(values, qsize)[source]¶

Queues up readings from values (the number of readings queued is determined by qsize) and begins yielding values only when the queue is full. For example, to “cascade” values along a sequence of LEDs:

from gpiozero import LEDBoard, Button
from gpiozero.tools import queued
from signal import pause

leds = LEDBoard(5, 6, 13, 19, 26)
btn = Button(17)

for i in range(4):
    leds[i].source = queued(leds[i + 1], 5)
    leds[i].source_delay = 0.01

leds[4].source = btn

pause()

gpiozero.tools.smoothed(values, qsize, average=<function mean>)[source]¶

Queues up readings from values (the number of readings queued is determined by qsize) and begins yielding the average of the last qsize values when the queue is full. The larger the qsize, the more the values are smoothed. For example, to smooth the analog values read from an ADC:

from gpiozero import MCP3008
from gpiozero.tools import smoothed

adc = MCP3008(channel=0)

for value in smoothed(adc, 5):
    print(value)

gpiozero.tools.scaled(values, output_min, output_max, input_min=0, input_max=1)[source]¶

Returns values scaled from output_min to output_max, assuming that all items in values lie between input_min and input_max (which default to 0 and 1 respectively). For example, to control the direction of a motor (which is represented as a value between -1 and 1) using a potentiometer (which typically provides values between 0 and 1):

from gpiozero import Motor, MCP3008
from gpiozero.tools import scaled
from signal import pause

motor = Motor(20, 21)
pot = MCP3008(channel=0)

motor.source = scaled(pot, -1, 1)

pause()

Warning

If values contains elements that lie outside input_min to input_max (inclusive) then the function will not produce values that lie within output_min to output_max (inclusive).

Combining sources¶

gpiozero.tools.all_values(*values)[source]¶

Returns the logical conjunction of all supplied values (the result is only True if and only if all input values are simultaneously True). One or more values can be specified. For example, to light an LED only when both buttons are pressed:

from gpiozero import LED, Button
from gpiozero.tools import all_values
from signal import pause

led = LED(4)
btn1 = Button(20)
btn2 = Button(21)

led.source = all_values(btn1, btn2)

pause()

gpiozero.tools.any_values(*values)[source]¶

Returns the logical disjunction of all supplied values (the result is True if any of the input values are currently True). One or more values can be specified. For example, to light an LED when any button is pressed:

from gpiozero import LED, Button
from gpiozero.tools import any_values
from signal import pause

led = LED(4)
btn1 = Button(20)
btn2 = Button(21)

led.source = any_values(btn1, btn2)

pause()

gpiozero.tools.averaged(*values)[source]¶

Returns the mean of all supplied values. One or more values can be specified. For example, to light a PWMLED as the average of several potentiometers connected to an MCP3008 ADC:

from gpiozero import MCP3008, PWMLED
from gpiozero.tools import averaged
from signal import pause

pot1 = MCP3008(channel=0)
pot2 = MCP3008(channel=1)
pot3 = MCP3008(channel=2)
led = PWMLED(4)

led.source = averaged(pot1, pot2, pot3)

pause()

gpiozero.tools.multiplied(*values)[source]¶

Returns the product of all supplied values. One or more values can be specified. For example, to light a PWMLED as the product (i.e. multiplication) of several potentiometers connected to an MCP3008 ADC:

from gpiozero import MCP3008, PWMLED
from gpiozero.tools import multiplied
from signal import pause

pot1 = MCP3008(channel=0)
pot2 = MCP3008(channel=1)
pot3 = MCP3008(channel=2)
led = PWMLED(4)

led.source = multiplied(pot1, pot2, pot3)

pause()

gpiozero.tools.summed(*values)[source]¶

Returns the sum of all supplied values. One or more values can be specified. For example, to light a PWMLED as the (scaled) sum of several potentiometers connected to an MCP3008 ADC:

from gpiozero import MCP3008, PWMLED
from gpiozero.tools import summed, scaled
from signal import pause

pot1 = MCP3008(channel=0)
pot2 = MCP3008(channel=1)
pot3 = MCP3008(channel=2)
led = PWMLED(4)

led.source = scaled(summed(pot1, pot2, pot3), 0, 1, 0, 3)

pause()

gpiozero.tools.zip_values(*devices)[source]¶

Provides a source constructed from the values of each item, for example:

from gpiozero import MCP3008, Robot
from gpiozero.tools import zip_values
from signal import pause

robot = Robot(left=(4, 14), right=(17, 18))

left = MCP3008(0)
right = MCP3008(1)

robot.source = zip_values(left, right)

pause()

zip_values(left, right) is equivalent to zip(left.values, right.values).

Artificial sources¶

gpiozero.tools.alternating_values(initial_value=False)[source]¶

Provides an infinite source of values alternating between True and False, starting wth initial_value (which defaults to False). For example, to produce a flashing LED:

from gpiozero import LED
from gpiozero.tools import alternating_values
from signal import pause

red = LED(2)

red.source_delay = 0.5
red.source = alternating_values()

pause()

gpiozero.tools.cos_values(period=360)[source]¶

Provides an infinite source of values representing a cosine wave (from -1 to +1) which repeats every period values. For example, to produce a “siren” effect with a couple of LEDs that repeats once a second:

from gpiozero import PWMLED
from gpiozero.tools import cos_values, scaled_half, inverted
from signal import pause

red = PWMLED(2)
blue = PWMLED(3)

red.source_delay = 0.01
blue.source_delay = red.source_delay
red.source = scaled_half(cos_values(100))
blue.source = inverted(red)

pause()

If you require a different range than -1 to +1, see scaled().

gpiozero.tools.ramping_values(period=360)[source]¶

Provides an infinite source of values representing a triangle wave (from 0 to 1 and back again) which repeats every period values. For example, to pulse an LED once a second:

from gpiozero import PWMLED
from gpiozero.tools import ramping_values
from signal import pause

red = PWMLED(2)

red.source_delay = 0.01
red.source = ramping_values(100)

pause()

If you require a wider range than 0 to 1, see scaled().

gpiozero.tools.random_values()[source]¶

Provides an infinite source of random values between 0 and 1. For example, to produce a “flickering candle” effect with an LED:

from gpiozero import PWMLED
from gpiozero.tools import random_values
from signal import pause

led = PWMLED(4)

led.source = random_values()

pause()

If you require a wider range than 0 to 1, see scaled().

gpiozero.tools.sin_values(period=360)[source]¶

Provides an infinite source of values representing a sine wave (from -1 to +1) which repeats every period values. For example, to produce a “siren” effect with a couple of LEDs that repeats once a second:

from gpiozero import PWMLED
from gpiozero.tools import sin_values, scaled_half, inverted
from signal import pause

red = PWMLED(2)
blue = PWMLED(3)

red.source_delay = 0.01
blue.source_delay = red.source_delay
red.source = scaled_half(sin_values(100))
blue.source = inverted(red)

pause()

If you require a different range than -1 to +1, see scaled().

API - Fonts¶

GPIO Zero includes a concept of “fonts” which is somewhat different to that you may be familiar with. While a typical printing font determines how a particular character is rendered on a page, a GPIO Zero font determines how a particular character is rendered by a series of lights, like LED segments (e.g. with LEDCharDisplay or LEDMultiCharDisplay).

As a result, GPIO Zero’s fonts are quite crude affairs, being little more than mappings of characters to tuples of LED states. Still, it helps to have a “friendly” format for creating such fonts, and in this module the library provides several routines for this purpose.

The module itself is typically imported as follows:

from gpiozero import fonts

Font Parsing¶

gpiozero.fonts.load_font_7seg(filename_or_obj)[source]¶

Given a filename or a file-like object, parse it as an font definition for a 7-segment display, returning a dict suitable for use with LEDCharDisplay.

The file-format is a simple text-based format in which blank and #-prefixed lines are ignored. All other lines are assumed to be groups of character definitions which are cells of 3x3 characters laid out as follows:

Ca
fgb
edc

Where C is the character being defined, and a-g define the states of the LEDs for that position. a, d, and g are on if they are “_”. b, c, e, and f are on if they are “|”. Any other character in these positions is considered off. For example, you might define the following characters:

 .  0_  1.  2_  3_  4.  5_  6_  7_  8_  9_
... |.| ..| ._| ._| |_| |_. |_. ..| |_| |_|
... |_| ..| |_. ._| ..| ._| |_| ..| |_| ._|

In the example above, empty locations are marked with “.” but could mostly be left as spaces. However, the first item defines the space (” “) character and needs some non-space characters in its definition as the parser also strips empty columns (as typically occur between character definitions). This is also why the definition for “1” must include something to fill the middle column.

gpiozero.fonts.load_font_14seg(filename_or_obj)[source]¶

Given a filename or a file-like object, parse it as a font definition for a 14-segment display, returning a dict suitable for use with LEDCharDisplay.

The file-format is a simple text-based format in which blank and #-prefixed lines are ignored. All other lines are assumed to be groups of character definitions which are cells of 5x5 characters laid out as follows:

X.a..
fijkb
.g.h.
elmnc
..d..

Where X is the character being defined, and a-n define the states of the LEDs for that position. a, d, g, and h are on if they are “-“. b, c, e, f, j, and m are on if they are “|”. i and n are on if they are “”. Finally, k and l are on if they are “/”. Any other character in these positions is considered off. For example, you might define the following characters:

 .... 0---  1..   2---  3---  4     5---  6---  7---. 8---  9---
..... |  /|    /|     |     | |   | |     |        /  |   | |   |
..... | / |     |  ---    --   ---|  ---  |---    |    ---   ---|
..... |/  |     | |         |     |     | |   |   |   |   |     |
.....  ---         ---   ---         ---   ---         ---

In the example above, several locations have extraneous characters. For example, the “/” in the center of the “0” definition, or the “-” in the middle of the “8”. These locations are ignored, but filled in nonetheless to make the shape more obvious.

These extraneous locations could equally well be left as spaces. However, the first item defines the space (” “) character and needs some non-space characters in its definition as the parser also strips empty columns (as typically occur between character definitions) and verifies that definitions are 5 columns wide and 5 rows high.

This also explains why place-holder characters (“.”) have been inserted at the top of the definition of the “1” character. Otherwise the parser will strip these empty columns and decide the definition is invalid (as the result is only 3 columns wide).

gpiozero.fonts.load_segment_font(filename_or_obj, width, height, pins)[source]¶

A generic function for parsing segment font definition files.

If you’re working with “standard” 7-segment or 14-segment displays you don’t want this function; see load_font_7seg() or load_font_14seg() instead. However, if you are working with another style of segmented display and wish to construct a parser for a custom format, this is the function you want.

The filename_or_obj parameter is simply the file-like object or filename to load. This is typically passed in from the calling function.

The width and height parameters give the width and height in characters of each character definition. For example, these are 3 and 3 for 7-segment displays. Finally, pins is a list of tuples that defines the position of each pin definition in the character array, and the character that marks that position “active”.

For example, for 7-segment displays this function is called as follows:

load_segment_font(filename_or_obj, width=3, height=3, pins=[
    (1, '_'), (5, '|'), (8, '|'), (7, '_'),
    (6, '|'), (3, '|'), (4, '_')])

This dictates that each character will be defined by a 3x3 character grid which will be converted into a nine-character string like so:

012
345  ==>  '012345678'
678

Position 0 is always assumed to be the character being defined. The pins list then specifies: the first pin is the character at position 1 which will be “on” when that character is “_”. The second pin is the character at position 5 which will be “on” when that character is “|”, and so on.

API - Tones¶

GPIO Zero includes a Tone class intended for use with the TonalBuzzer. This class is in the tones module of GPIO Zero and is typically imported as follows:

from gpiozero.tones import Tone

Tone¶

class gpiozero.tones.Tone[source]¶

Represents a frequency of sound in a variety of musical notations.

Tone class can be used with the TonalBuzzer class to easily represent musical tones. The class can be constructed in a variety of ways. For example as a straight frequency in Hz (which is the internal storage format), as an integer MIDI note, or as a string representation of a musical note.

All the following constructors are equivalent ways to construct the typical tuning note, concert A at 440Hz, which is MIDI note #69:

>>> from gpiozero.tones import Tone
>>> Tone(440.0)
>>> Tone(69)
>>> Tone('A4')

If you do not want the constructor to guess which format you are using (there is some ambiguity between frequencies and MIDI notes at the bottom end of the frequencies, from 128Hz down), you can use one of the explicit constructors, from_frequency(), from_midi(), or from_note(), or you can specify a keyword argument when constructing:

>>> Tone.from_frequency(440)
>>> Tone.from_midi(69)
>>> Tone.from_note('A4')
>>> Tone(frequency=440)
>>> Tone(midi=69)
>>> Tone(note='A4')

Several attributes are provided to permit conversion to any of the supported construction formats: frequency, midi, and note. Methods are provided to step up() or down() to adjacent MIDI notes.

Warning

Currently Tone derives from float and can be used as a floating point number in most circumstances (addition, subtraction, etc). This part of the API is not yet considered “stable”; i.e. we may decide to enhance / change this behaviour in future versions.

down(n=1)[source]¶: Return the Tone n semi-tones below this frequency (n defaults to 1).

classmethod from_frequency(freq)[source]¶: Construct a Tone from a frequency specified in Hz which must be a positive floating-point value in the range 0 < freq <= 20000.

classmethod from_midi(midi_note)[source]¶: Construct a Tone from a MIDI note, which must be an integer in the range 0 to 127. For reference, A4 (concert A typically used for tuning) is MIDI note #69.

classmethod from_note(note)[source]¶

Construct a Tone from a musical note which must consist of a capital letter A through G, followed by an optional semi-tone modifier (“b” for flat, “#” for sharp, or their Unicode equivalents), followed by an octave number (0 through 9).

For example concert A, the typical tuning note at 440Hz, would be represented as “A4”. One semi-tone above this would be “A#4” or alternatively “Bb4”. Unicode representations of sharp and flat are also accepted.

up(n=1)[source]¶: Return the Tone n semi-tones above this frequency (n defaults to 1).

frequency¶: Return the frequency of the tone in Hz.

midi¶: Return the (nearest) MIDI note to the tone’s frequency. This will be an integer number in the range 0 to 127. If the frequency is outside the range represented by MIDI notes (which is approximately 8Hz to 12.5KHz) ValueError exception will be raised.

note¶: Return the (nearest) note to the tone’s frequency. This will be a string in the form accepted by from_note(). If the frequency is outside the range represented by this format (“A0” is approximately 27.5Hz, and “G9” is approximately 12.5Khz) a ValueError exception will be raised.

API - Pi Information¶

The GPIO Zero library also contains a database of information about the various revisions of the Raspberry Pi computer. This is used internally to raise warnings when non-physical pins are used, or to raise exceptions when pull-downs are requested on pins with physical pull-up resistors attached. The following functions and classes can be used to query this database:

pi_info¶

gpiozero.pi_info(revision=None)[source]¶

Returns a PiBoardInfo instance containing information about a revision of the Raspberry Pi.

Parameters:	revision (str) – The revision of the Pi to return information about. If this is omitted or `None` (the default), then the library will attempt to determine the model of Pi it is running on and return information about that.

PiBoardInfo¶

class gpiozero.PiBoardInfo[source]¶

This class is a namedtuple() derivative used to represent information about a particular model of Raspberry Pi. While it is a tuple, it is strongly recommended that you use the following named attributes to access the data contained within. The object can be used in format strings with various custom format specifications:

from gpiozero import *

print('{0}'.format(pi_info()))
print('{0:full}'.format(pi_info()))
print('{0:board}'.format(pi_info()))
print('{0:specs}'.format(pi_info()))
print('{0:headers}'.format(pi_info()))

“color” and “mono” can be prefixed to format specifications to force the use of ANSI color codes. If neither is specified, ANSI codes will only be used if stdout is detected to be a tty:

print('{0:color board}'.format(pi_info())) # force use of ANSI codes
print('{0:mono board}'.format(pi_info())) # force plain ASCII

physical_pin(function)[source]¶

Return the physical pin supporting the specified function. If no pins support the desired function, this function raises PinNoPins. If multiple pins support the desired function, PinMultiplePins will be raised (use physical_pins() if you expect multiple pins in the result, such as for electrical ground).

Parameters:	function (str) – The pin function you wish to search for. Usually this is something like “GPIO9” for Broadcom GPIO pin 9.

physical_pins(function)[source]¶

Return the physical pins supporting the specified function as tuples of (header, pin_number) where header is a string specifying the header containing the pin_number. Note that the return value is a set which is not indexable. Use physical_pin() if you are expecting a single return value.

Parameters:	function (str) – The pin function you wish to search for. Usually this is something like “GPIO9” for Broadcom GPIO pin 9, or “GND” for all the pins connecting to electrical ground.

pprint(color=None)[source]¶

Pretty-print a representation of the board along with header diagrams.

If color is None (the default), the diagram will include ANSI color codes if stdout is a color-capable terminal. Otherwise color can be set to True or False to force color or monochrome output.

pulled_up(function)[source]¶

Returns a bool indicating whether a physical pull-up is attached to the pin supporting the specified function. Either PinNoPins or PinMultiplePins may be raised if the function is not associated with a single pin.

Parameters:	function (str) – The pin function you wish to determine pull-up for. Usually this is something like “GPIO9” for Broadcom GPIO pin 9.

to_gpio(spec)[source]¶

Parses a pin spec, returning the equivalent Broadcom GPIO port number or raising a ValueError exception if the spec does not represent a GPIO port.

The spec may be given in any of the following forms:

An integer, which will be accepted as a GPIO number
‘GPIOn’ where n is the GPIO number
‘WPIn’ where n is the wiringPi pin number
‘BCMn’ where n is the GPIO number (alias of GPIOn)
‘BOARDn’ where n is the physical pin number on the main header
‘h:n’ where h is the header name and n is the physical pin number (for example J8:5 is physical pin 5 on header J8, which is the main header on modern Raspberry Pis)

revision¶: A string indicating the revision of the Pi. This is unique to each revision and can be considered the “key” from which all other attributes are derived. However, in itself the string is fairly meaningless.

model¶: A string containing the model of the Pi (for example, “B”, “B+”, “A+”, “2B”, “CM” (for the Compute Module), or “Zero”).

pcb_revision¶: A string containing the PCB revision number which is silk-screened onto the Pi (on some models).

Note

This is primarily useful to distinguish between the model B revision 1.0 and 2.0 (not to be confused with the model 2B) which had slightly different pinouts on their 26-pin GPIO headers.

released¶: A string containing an approximate release date for this revision of the Pi (formatted as yyyyQq, e.g. 2012Q1 means the first quarter of 2012).

soc¶: A string indicating the SoC (system on a chip) that this revision of the Pi is based upon.

manufacturer¶: A string indicating the name of the manufacturer (usually “Sony” but a few others exist).

memory¶: An integer indicating the amount of memory (in Mb) connected to the SoC.

Note

This can differ substantially from the amount of RAM available to the operating system as the GPU’s memory is shared with the CPU. When the camera module is activated, at least 128Mb of RAM is typically reserved for the GPU.

storage¶: A string indicating the type of bootable storage used with this revision of Pi, e.g. “SD”, “MicroSD”, or “eMMC” (for the Compute Module).

usb¶: An integer indicating how many USB ports are physically present on this revision of the Pi, of any type.

Note

This does not include the micro-USB or USB-C port used to power the Pi.

usb3¶: An integer indicating how many of the USB ports are USB3 ports on this revision of the Pi.

ethernet¶: An integer indicating how many Ethernet ports are physically present on this revision of the Pi.

eth_speed¶: An integer indicating the maximum speed (in Mbps) of the Ethernet ports (if any). If no Ethernet ports are present, this is 0.

wifi¶: A bool indicating whether this revision of the Pi has wifi built-in.

bluetooth¶: A bool indicating whether this revision of the Pi has bluetooth built-in.

csi¶: An integer indicating the number of CSI (camera) ports available on this revision of the Pi.

dsi¶: An integer indicating the number of DSI (display) ports available on this revision of the Pi.

headers¶

A dictionary which maps header labels to HeaderInfo tuples. For example, to obtain information about header P1 you would query headers['P1']. To obtain information about pin 12 on header J8 you would query headers['J8'].pins[12].

A rendered version of this data can be obtained by using the PiBoardInfo object in a format string:

from gpiozero import *
print('{0:headers}'.format(pi_info()))

board¶

An ASCII art rendition of the board, primarily intended for console pretty-print usage. A more usefully rendered version of this data can be obtained by using the PiBoardInfo object in a format string. For example:

from gpiozero import *
print('{0:board}'.format(pi_info()))

HeaderInfo¶

class gpiozero.HeaderInfo[source]¶

This class is a namedtuple() derivative used to represent information about a pin header on a board. The object can be used in a format string with various custom specifications:

from gpiozero import *

print('{0}'.format(pi_info().headers['J8']))
print('{0:full}'.format(pi_info().headers['J8']))
print('{0:col2}'.format(pi_info().headers['P1']))
print('{0:row1}'.format(pi_info().headers['P1']))

“color” and “mono” can be prefixed to format specifications to force the use of ANSI color codes. If neither is specified, ANSI codes will only be used if stdout is detected to be a tty:

print('{0:color row2}'.format(pi_info().headers['J8'])) # force use of ANSI codes
print('{0:mono row2}'.format(pi_info().headers['P1'])) # force plain ASCII

The following attributes are defined:

pprint(color=None)[source]¶

Pretty-print a diagram of the header pins.

If color is None (the default, the diagram will include ANSI color codes if stdout is a color-capable terminal). Otherwise color can be set to True or False to force color or monochrome output.

name¶: The name of the header, typically as it appears silk-screened on the board (e.g. “P1” or “J8”).

rows¶: The number of rows on the header.

columns¶: The number of columns on the header.

pins¶: A dictionary mapping physical pin numbers to PinInfo tuples.

PinInfo¶

class gpiozero.PinInfo[source]¶

This class is a namedtuple() derivative used to represent information about a pin present on a GPIO header. The following attributes are defined:

number¶: An integer containing the physical pin number on the header (starting from 1 in accordance with convention).

function¶: A string describing the function of the pin. Some common examples include “GND” (for pins connecting to ground), “3V3” (for pins which output 3.3 volts), “GPIO9” (for GPIO9 in the Broadcom numbering scheme), etc.

pull_up¶: A bool indicating whether the pin has a physical pull-up resistor permanently attached (this is usually False but GPIO2 and GPIO3 are usually True). This is used internally by gpiozero to raise errors when pull-down is requested on a pin with a physical pull-up resistor.

row¶: An integer indicating on which row the pin is physically located in the header (1-based)

col¶: An integer indicating in which column the pin is physically located in the header (1-based)

API - Pins¶

As of release 1.1, the GPIO Zero library can be roughly divided into two things: pins and the devices that are connected to them. The majority of the documentation focuses on devices as pins are below the level that most users are concerned with. However, some users may wish to take advantage of the capabilities of alternative GPIO implementations or (in future) use GPIO extender chips. This is the purpose of the pins portion of the library.

When you construct a device, you pass in a pin specification. This is passed to a pin Factory which turns it into a Pin implementation. The default factory can be queried (and changed) with Device.pin_factory. However, all classes (even internal devices) accept a pin_factory keyword argument to their constructors permitting the factory to be overridden on a per-device basis (the reason for allowing per-device factories is made apparent in the Configuring Remote GPIO chapter).

This is illustrated in the following flow-chart:

The default factory is constructed when the first device is initialised; if no default factory can be constructed (e.g. because no GPIO implementations are installed, or all of them fail to load for whatever reason), a BadPinFactory exception will be raised at construction time.

After importing gpiozero, until constructing a gpiozero device, the pin factory is None, but at the point of first construction the default pin factory will come into effect:

pi@raspberrypi:~ $ python3
Python 3.7.3 (default, Apr  3 2019, 05:39:12)
[GCC 8.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> from gpiozero import Device, LED
>>> print(Device.pin_factory)
None
>>> led = LED(2)
>>> Device.pin_factory
<gpiozero.pins.rpigpio.RPiGPIOFactory object at 0xb667ae30>
>>> led.pin_factory
<gpiozero.pins.rpigpio.RPiGPIOFactory object at 0xb6323530>

As above, on a Raspberry Pi with the RPi.GPIO library installed, (assuming no environment variables are set), the default pin factory will be RPiGPIOFactory.

On a PC (with no pin libraries installed and no environment variables set), importing will work but attempting to create a device will raise BadPinFactory:

ben@magicman:~ $ python3
Python 3.6.8 (default, Aug 20 2019, 17:12:48)
[GCC 8.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> from gpiozero import Device, LED
>>> print(Device.pin_factory)
None
>>> led = LED(2)
...
BadPinFactory: Unable to load any default pin factory!

Changing the pin factory¶

The default pin factory can be replaced by specifying a value for the GPIOZERO_PIN_FACTORY environment variable. For example:

pi@raspberrypi:~ $ GPIOZERO_PIN_FACTORY=native python3
Python 3.7.3 (default, Apr  3 2019, 05:39:12)
[GCC 8.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> from gpiozero import Device
>>> Device._default_pin_factory()
<gpiozero.pins.native.NativeFactory object at 0x762c26b0>

To set the GPIOZERO_PIN_FACTORY for the rest of your session you can export this value:

pi@raspberrypi:~ $ export GPIOZERO_PIN_FACTORY=native
pi@raspberrypi:~ $ python3
Python 3.7.3 (default, Apr  3 2019, 05:39:12)
[GCC 8.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import gpiozero
>>> Device._default_pin_factory()
<gpiozero.pins.native.NativeFactory object at 0x762c26b0>
>>> quit()
pi@raspberrypi:~ $ python3
Python 3.7.3 (default, Apr  3 2019, 05:39:12)
[GCC 8.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import gpiozero
>>> Device._default_pin_factory()
<gpiozero.pins.native.NativeFactory object at 0x762c26b0>

If you add the export command to your ~/.bashrc file, you’ll set the default pin factory for all future sessions too.

If the environment variable is set, the corresponding pin factory will be used, otherwise each of the four GPIO pin factories will be attempted to be used in turn.

The following values, and the corresponding Factory and Pin classes are listed in the table below. Factories are listed in the order that they are tried by default.

Name	Factory class	Pin class
rpigpio	`gpiozero.pins.rpigpio.RPiGPIOFactory`	`gpiozero.pins.rpigpio.RPiGPIOPin`
rpio	`gpiozero.pins.rpio.RPIOFactory`	`gpiozero.pins.rpio.RPIOPin`
pigpio	`gpiozero.pins.pigpio.PiGPIOFactory`	`gpiozero.pins.pigpio.PiGPIOPin`
native	`gpiozero.pins.native.NativeFactory`	`gpiozero.pins.native.NativePin`

If you need to change the default pin factory from within a script, either set Device.pin_factory to the new factory instance to use:

from gpiozero.pins.native import NativeFactory
from gpiozero import Device, LED

Device.pin_factory = NativeFactory()

# These will now implicitly use NativePin instead of RPiGPIOPin
led1 = LED(16)
led2 = LED(17)

Or use the pin_factory keyword parameter mentioned above:

from gpiozero.pins.native import NativeFactory
from gpiozero import LED

my_factory = NativeFactory()

# This will use NativePin instead of RPiGPIOPin for led1
# but led2 will continue to use RPiGPIOPin
led1 = LED(16, pin_factory=my_factory)
led2 = LED(17)

Certain factories may take default information from additional sources. For example, to default to creating pins with gpiozero.pins.pigpio.PiGPIOPin on a remote pi called “remote-pi” you can set the PIGPIO_ADDR environment variable when running your script:

$ GPIOZERO_PIN_FACTORY=pigpio PIGPIO_ADDR=remote-pi python3 my_script.py

Like the GPIOZERO_PIN_FACTORY value, these can be exported from your ~/.bashrc script too.

Warning

The astute and mischievous reader may note that it is possible to mix factories, e.g. using RPiGPIOFactory for one pin, and NativeFactory for another. This is unsupported, and if it results in your script crashing, your components failing, or your Raspberry Pi turning into an actual raspberry pie, you have only yourself to blame.

Sensible uses of multiple pin factories are given in Configuring Remote GPIO.

Mock pins¶

There’s also a MockFactory which generates entirely fake pins. This was originally intended for GPIO Zero developers who wish to write tests for devices without having to have the physical device wired in to their Pi. However, they have also proven useful in developing GPIO Zero scripts without having a Pi to hand. This pin factory will never be loaded by default; it must be explicitly specified, either by setting an environment variable or setting the pin factory within the script. For example:

pi@raspberrypi:~ $ GPIOZERO_PIN_FACTORY=mock python3

or:

from gpiozero import Device, LED
from gpiozero.pins.mock import MockFactory

Device.pin_factory = MockFactory()

led = LED(2)

You can create device objects and inspect their value changing as you’d expect:

pi@raspberrypi:~ $ GPIOZERO_PIN_FACTORY=mock python3
Python 3.7.3 (default, Apr  3 2019, 05:39:12)
[GCC 8.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> from gpiozero import LED
>>> led = LED(2)
>>> led.value
0
>>> led.on()
>>> led.value
1

You can even control pin state changes to simulate device behaviour:

>>> from gpiozero import LED, Button

# Construct a couple of devices attached to mock pins 16 and 17, and link the devices
>>> led = LED(17)
>>> btn = Button(16)
>>> led.source = btn

# Initailly the button isn't "pressed" so the LED should be off
>>> led.value
0

# Drive the pin low (this is what would happen electrically when the button is pressed)
>>> btn.pin.drive_low()
# The LED is now on
>>> led.value
1

>>> btn.pin.drive_high()
# The button is now "released", so the LED should be off again
>>> led.value
0

Several sub-classes of mock pins exist for emulating various other things (pins that do/don’t support PWM, pins that are connected together, pins that drive high after a delay, etc), for example, you have to use MockPWMPin to be able to use devices requiring PWM:

pi@raspberrypi:~ $ GPIOZERO_PIN_FACTORY=mock GPIOZERO_MOCK_PIN_CLASS=mockpwmpin python3

or:

from gpiozero import Device, LED
from gpiozero.pins.mock import MockFactory, MockPWMPin

Device.pin_factory = MockFactory(pin_class=MockPWMPin)

led = LED(2)

Interested users are invited to read the GPIO Zero test suite for further examples of usage.

Base classes¶

class gpiozero.Factory[source]¶

Generates pins and SPI interfaces for devices. This is an abstract base class for pin factories. Descendents must override the following methods:

ticks()
ticks_diff()

Descendents may override the following methods, if applicable:

close()
reserve_pins()
release_pins()
release_all()
pin()
spi()
_get_pi_info()

close()[source]¶: Closes the pin factory. This is expected to clean up all resources manipulated by the factory. It it typically called at script termination.

pin(spec)[source]¶: Creates an instance of a Pin descendent representing the specified pin.

Warning

Descendents must ensure that pin instances representing the same hardware are identical; i.e. two separate invocations of pin() for the same pin specification must return the same object.

release_all(reserver)[source]¶: Releases all pin reservations taken out by reserver. See release_pins() for further information).

release_pins(reserver, *pins)[source]¶: Releases the reservation of reserver against pins. This is typically called during close() to clean up reservations taken during construction. Releasing a reservation that is not currently held will be silently ignored (to permit clean-up after failed / partial construction).

reserve_pins(requester, *pins)[source]¶: Called to indicate that the device reserves the right to use the specified pins. This should be done during device construction. If pins are reserved, you must ensure that the reservation is released by eventually called release_pins().

spi(**spi_args)[source]¶: Returns an instance of an SPI interface, for the specified SPI port and device, or for the specified pins (clock_pin, mosi_pin, miso_pin, and select_pin). Only one of the schemes can be used; attempting to mix port and device with pin numbers will raise SPIBadArgs.

ticks()[source]¶

Return the current ticks, according to the factory. The reference point is undefined and thus the result of this method is only meaningful when compared to another value returned by this method.

The format of the time is also arbitrary, as is whether the time wraps after a certain duration. Ticks should only be compared using the ticks_diff() method.

ticks_diff(later, earlier)[source]¶: Return the time in seconds between two ticks() results. The arguments are specified in the same order as they would be in the formula later - earlier but the result is guaranteed to be in seconds, and to be positive even if the ticks “wrapped” between calls to ticks().

pi_info¶

Returns a PiBoardInfo instance representing the Pi that instances generated by this factory will be attached to.

If the pins represented by this class are not directly attached to a Pi (e.g. the pin is attached to a board attached to the Pi, or the pins are not on a Pi at all), this may return None.

class gpiozero.Pin[source]¶

Abstract base class representing a pin attached to some form of controller, be it GPIO, SPI, ADC, etc.

Descendents should override property getters and setters to accurately represent the capabilities of pins. Descendents must override the following methods:

_get_function()
_set_function()
_get_state()

Descendents may additionally override the following methods, if applicable:

close()
output_with_state()
input_with_pull()
_set_state()
_get_frequency()
_set_frequency()
_get_pull()
_set_pull()
_get_bounce()
_set_bounce()
_get_edges()
_set_edges()
_get_when_changed()
_set_when_changed()

close()[source]¶: Cleans up the resources allocated to the pin. After this method is called, this Pin instance may no longer be used to query or control the pin’s state.

input_with_pull(pull)[source]¶

Sets the pin’s function to “input” and specifies an initial pull-up for the pin. By default this is equivalent to performing:

pin.function = 'input'
pin.pull = pull

However, descendents may override this order to provide the smallest possible delay between configuring the pin for input and pulling the pin up/down (which can be important for avoiding “blips” in some configurations).

output_with_state(state)[source]¶

Sets the pin’s function to “output” and specifies an initial state for the pin. By default this is equivalent to performing:

pin.function = 'output'
pin.state = state

However, descendents may override this in order to provide the smallest possible delay between configuring the pin for output and specifying an initial value (which can be important for avoiding “blips” in active-low configurations).

bounce¶

The amount of bounce detection (elimination) currently in use by edge detection, measured in seconds. If bounce detection is not currently in use, this is None.

For example, if edges is currently “rising”, bounce is currently 5/1000 (5ms), then the waveform below will only fire when_changed on two occasions despite there being three rising edges:

TIME 0...1...2...3...4...5...6...7...8...9...10..11..12 ms

bounce elimination   |===================| |==============

HIGH - - - - >       ,--. ,--------------. ,--.
                     |  | |              | |  |
                     |  | |              | |  |
LOW  ----------------'  `-'              `-'  `-----------
                     :                     :
                     :                     :
               when_changed          when_changed
                   fires                 fires

If the pin does not support edge detection, attempts to set this property will raise PinEdgeDetectUnsupported. If the pin supports edge detection, the class must implement bounce detection, even if only in software.

edges¶

The edge that will trigger execution of the function or bound method assigned to when_changed. This can be one of the strings “both” (the default), “rising”, “falling”, or “none”:

HIGH - - - - >           ,--------------.
                         |              |
                         |              |
LOW  --------------------'              `--------------
                         :              :
                         :              :
Fires when_changed     "both"         "both"
when edges is ...     "rising"       "falling"

If the pin does not support edge detection, attempts to set this property will raise PinEdgeDetectUnsupported.

frequency¶

The frequency (in Hz) for the pin’s PWM implementation, or None if PWM is not currently in use. This value always defaults to None and may be changed with certain pin types to activate or deactivate PWM.

If the pin does not support PWM, PinPWMUnsupported will be raised when attempting to set this to a value other than None.

function¶

The function of the pin. This property is a string indicating the current function or purpose of the pin. Typically this is the string “input” or “output”. However, in some circumstances it can be other strings indicating non-GPIO related functionality.

With certain pin types (e.g. GPIO pins), this attribute can be changed to configure the function of a pin. If an invalid function is specified, for this attribute, PinInvalidFunction will be raised.

pull¶

The pull-up state of the pin represented as a string. This is typically one of the strings “up”, “down”, or “floating” but additional values may be supported by the underlying hardware.

If the pin does not support changing pull-up state (for example because of a fixed pull-up resistor), attempts to set this property will raise PinFixedPull. If the specified value is not supported by the underlying hardware, PinInvalidPull is raised.

state¶

The state of the pin. This is 0 for low, and 1 for high. As a low level view of the pin, no swapping is performed in the case of pull ups (see pull for more information):

HIGH - - - - >       ,----------------------
                     |
                     |
LOW  ----------------'

Descendents which implement analog, or analog-like capabilities can return values between 0 and 1. For example, pins implementing PWM (where frequency is not None) return a value between 0.0 and 1.0 representing the current PWM duty cycle.

If a pin is currently configured for input, and an attempt is made to set this attribute, PinSetInput will be raised. If an invalid value is specified for this attribute, PinInvalidState will be raised.

when_changed¶

A function or bound method to be called when the pin’s state changes (more specifically when the edge specified by edges is detected on the pin). The function or bound method must accept two parameters: the first will report the ticks (from Factory.ticks()) when the pin’s state changed, and the second will report the pin’s current state.

Warning

Depending on hardware support, the state is not guaranteed to be accurate. For instance, many GPIO implementations will provide an interrupt indicating when a pin’s state changed but not what it changed to. In this case the pin driver simply reads the pin’s current state to supply this parameter, but the pin’s state may have changed since the interrupt. Exercise appropriate caution when relying upon this parameter.

If the pin does not support edge detection, attempts to set this property will raise PinEdgeDetectUnsupported.

class gpiozero.SPI(**kwargs)[source]¶

Abstract interface for Serial Peripheral Interface (SPI) implementations. Descendents must override the following methods:

transfer()
_get_clock_mode()

Descendents may override the following methods, if applicable:

read()
write()
_set_clock_mode()
_get_lsb_first()
_set_lsb_first()
_get_select_high()
_set_select_high()
_get_bits_per_word()
_set_bits_per_word()

read(n)[source]¶

Read n words of data from the SPI interface, returning them as a sequence of unsigned ints, each no larger than the configured bits_per_word of the interface.

This method is typically used with read-only devices that feature half-duplex communication. See transfer() for full duplex communication.

transfer(data)[source]¶

Write data to the SPI interface. data must be a sequence of unsigned integer words each of which will fit within the configured bits_per_word of the interface. The method returns the sequence of words read from the interface while writing occurred (full duplex communication).

The length of the sequence returned dictates the number of words of data written to the interface. Each word in the returned sequence will be an unsigned integer no larger than the configured bits_per_word of the interface.

write(data)[source]¶

Write data to the SPI interface. data must be a sequence of unsigned integer words each of which will fit within the configured bits_per_word of the interface. The method returns the number of words written to the interface (which may be less than or equal to the length of data).

This method is typically used with write-only devices that feature half-duplex communication. See transfer() for full duplex communication.

bits_per_word¶

Controls the number of bits that make up a word, and thus where the word boundaries appear in the data stream, and the maximum value of a word. Defaults to 8 meaning that words are effectively bytes.

Several implementations do not support non-byte-sized words.

clock_mode¶

Presents a value representing the clock_polarity and clock_phase attributes combined according to the following table:

mode	polarity (CPOL)	phase (CPHA)
0	False	False
1	False	True
2	True	False
3	True	True

Adjusting this value adjusts both the clock_polarity and clock_phase attributes simultaneously.

clock_phase¶

The phase of the SPI clock pin. If this is False (the default), data will be read from the MISO pin when the clock pin activates. Setting this to True will cause data to be read from the MISO pin when the clock pin deactivates. On many data sheets this is documented as the CPHA value. Whether the clock edge is rising or falling when the clock is considered activated is controlled by the clock_polarity attribute (corresponding to CPOL).

The following diagram indicates when data is read when clock_polarity is False, and clock_phase is False (the default), equivalent to CPHA 0:

    ,---.   ,---.   ,---.   ,---.   ,---.   ,---.   ,---.
CLK |   |   |   |   |   |   |   |   |   |   |   |   |   |
    |   |   |   |   |   |   |   |   |   |   |   |   |   |
----'   `---'   `---'   `---'   `---'   `---'   `---'   `-------
    :       :       :       :       :       :       :
MISO---.   ,---.   ,---.   ,---.   ,---.   ,---.   ,---.
  /     \ /     \ /     \ /     \ /     \ /     \ /     \
-{  Bit  X  Bit  X  Bit  X  Bit  X  Bit  X  Bit  X  Bit  }------
  \     / \     / \     / \     / \     / \     / \     /
   `---'   `---'   `---'   `---'   `---'   `---'   `---'

The following diagram indicates when data is read when clock_polarity is False, but clock_phase is True, equivalent to CPHA 1:

    ,---.   ,---.   ,---.   ,---.   ,---.   ,---.   ,---.
CLK |   |   |   |   |   |   |   |   |   |   |   |   |   |
    |   |   |   |   |   |   |   |   |   |   |   |   |   |
----'   `---'   `---'   `---'   `---'   `---'   `---'   `-------
        :       :       :       :       :       :       :
MISO   ,---.   ,---.   ,---.   ,---.   ,---.   ,---.   ,---.
      /     \ /     \ /     \ /     \ /     \ /     \ /     \
-----{  Bit  X  Bit  X  Bit  X  Bit  X  Bit  X  Bit  X  Bit  }--
      \     / \     / \     / \     / \     / \     / \     /
       `---'   `---'   `---'   `---'   `---'   `---'   `---'

clock_polarity¶

The polarity of the SPI clock pin. If this is False (the default), the clock pin will idle low, and pulse high. Setting this to True will cause the clock pin to idle high, and pulse low. On many data sheets this is documented as the CPOL value.

The following diagram illustrates the waveform when clock_polarity is False (the default), equivalent to CPOL 0:

       on      on      on      on      on      on      on
      ,---.   ,---.   ,---.   ,---.   ,---.   ,---.   ,---.
CLK   |   |   |   |   |   |   |   |   |   |   |   |   |   |
      |   |   |   |   |   |   |   |   |   |   |   |   |   |
------'   `---'   `---'   `---'   `---'   `---'   `---'   `------
idle       off     off     off     off     off     off       idle

The following diagram illustrates the waveform when clock_polarity is True, equivalent to CPOL 1:

idle       off     off     off     off     off     off       idle
------.   ,---.   ,---.   ,---.   ,---.   ,---.   ,---.   ,------
      |   |   |   |   |   |   |   |   |   |   |   |   |   |
CLK   |   |   |   |   |   |   |   |   |   |   |   |   |   |
      `---'   `---'   `---'   `---'   `---'   `---'   `---'
       on      on      on      on      on      on      on

lsb_first¶

Controls whether words are read and written LSB in (Least Significant Bit first) order. The default is False indicating that words are read and written in MSB (Most Significant Bit first) order. Effectively, this controls the Bit endianness of the connection.

The following diagram shows the a word containing the number 5 (binary 0101) transmitted on MISO with bits_per_word set to 4, and clock_mode set to 0, when lsb_first is False (the default):

    ,---.   ,---.   ,---.   ,---.
CLK |   |   |   |   |   |   |   |
    |   |   |   |   |   |   |   |
----'   `---'   `---'   `---'   `-----
    :     ,-------. :     ,-------.
MISO:     | :     | :     | :     |
    :     | :     | :     | :     |
----------' :     `-------' :     `----
    :       :       :       :
   MSB                     LSB

And now with lsb_first set to True (and all other parameters the same):

    ,---.   ,---.   ,---.   ,---.
CLK |   |   |   |   |   |   |   |
    |   |   |   |   |   |   |   |
----'   `---'   `---'   `---'   `-----
  ,-------. :     ,-------. :
MISO:     | :     | :     | :
  | :     | :     | :     | :
--' :     `-------' :     `-----------
    :       :       :       :
   LSB                     MSB

rate¶

Controls the speed of the SPI interface in Hz (or baud).

Note that most software SPI implementations ignore this property, and will raise SPIFixedRate if an attempt is made to set it, as they have no rate control (they simply bit-bang as fast as possible because typically this isn’t very fast anyway, and introducing measures to limit the rate would simply slow them down to the point of being useless).

select_high¶

If False (the default), the chip select line is considered active when it is pulled low. When set to True, the chip select line is considered active when it is driven high.

The following diagram shows the waveform of the chip select line, and the clock when clock_polarity is False, and select_high is False (the default):

---.                                                     ,------
__ |                                                     |
CS |      chip is selected, and will react to clock      |  idle
   `-----------------------------------------------------'

    ,---.   ,---.   ,---.   ,---.   ,---.   ,---.   ,---.
CLK |   |   |   |   |   |   |   |   |   |   |   |   |   |
    |   |   |   |   |   |   |   |   |   |   |   |   |   |
----'   `---'   `---'   `---'   `---'   `---'   `---'   `-------

And when select_high is True:

   ,-----------------------------------------------------.
CS |      chip is selected, and will react to clock      |  idle
   |                                                     |
---'                                                     `------

    ,---.   ,---.   ,---.   ,---.   ,---.   ,---.   ,---.
CLK |   |   |   |   |   |   |   |   |   |   |   |   |   |
    |   |   |   |   |   |   |   |   |   |   |   |   |   |
----'   `---'   `---'   `---'   `---'   `---'   `---'   `-------

class gpiozero.pins.pi.PiFactory[source]¶

Extends Factory. Abstract base class representing hardware attached to a Raspberry Pi. This forms the base of LocalPiFactory.

close()[source]¶: Closes the pin factory. This is expected to clean up all resources manipulated by the factory. It it typically called at script termination.

pin(spec)[source]¶: Creates an instance of a Pin descendent representing the specified pin.

Warning

Descendents must ensure that pin instances representing the same hardware are identical; i.e. two separate invocations of pin() for the same pin specification must return the same object.

release_pins(reserver, *pins)[source]¶: Releases the reservation of reserver against pins. This is typically called during close() to clean up reservations taken during construction. Releasing a reservation that is not currently held will be silently ignored (to permit clean-up after failed / partial construction).

reserve_pins(requester, *pins)[source]¶: Called to indicate that the device reserves the right to use the specified pins. This should be done during device construction. If pins are reserved, you must ensure that the reservation is released by eventually called release_pins().

spi(**spi_args)[source]¶

Returns an SPI interface, for the specified SPI port and device, or for the specified pins (clock_pin, mosi_pin, miso_pin, and select_pin). Only one of the schemes can be used; attempting to mix port and device with pin numbers will raise SPIBadArgs.

If the pins specified match the hardware SPI pins (clock on GPIO11, MOSI on GPIO10, MISO on GPIO9, and chip select on GPIO8 or GPIO7), and the spidev module can be imported, a hardware based interface (using spidev) will be returned. Otherwise, a software based interface will be returned which will use simple bit-banging to communicate.

Both interfaces have the same API, support clock polarity and phase attributes, and can handle half and full duplex communications, but the hardware interface is significantly faster (though for many simpler devices this doesn’t matter).

class gpiozero.pins.pi.PiPin(factory, number)[source]¶

Extends Pin. Abstract base class representing a multi-function GPIO pin attached to a Raspberry Pi. Descendents must override the following methods:

_get_function()
_set_function()
_get_state()
_call_when_changed()
_enable_event_detect()
_disable_event_detect()

Descendents may additionally override the following methods, if applicable:

close()
output_with_state()
input_with_pull()
_set_state()
_get_frequency()
_set_frequency()
_get_pull()
_set_pull()
_get_bounce()
_set_bounce()
_get_edges()
_set_edges()

class gpiozero.pins.local.LocalPiFactory[source]¶

Extends PiFactory. Abstract base class representing pins attached locally to a Pi. This forms the base class for local-only pin interfaces (RPiGPIOPin, RPIOPin, and NativePin).

static ticks()[source]¶

Return the current ticks, according to the factory. The reference point is undefined and thus the result of this method is only meaningful when compared to another value returned by this method.

The format of the time is also arbitrary, as is whether the time wraps after a certain duration. Ticks should only be compared using the ticks_diff() method.

static ticks_diff(later, earlier)[source]¶: Return the time in seconds between two ticks() results. The arguments are specified in the same order as they would be in the formula later - earlier but the result is guaranteed to be in seconds, and to be positive even if the ticks “wrapped” between calls to ticks().

class gpiozero.pins.local.LocalPiPin(factory, number)[source]¶: Extends PiPin. Abstract base class representing a multi-function GPIO pin attached to the local Raspberry Pi.

RPi.GPIO¶

class gpiozero.pins.rpigpio.RPiGPIOFactory[source]¶

Extends LocalPiFactory. Uses the RPi.GPIO library to interface to the Pi’s GPIO pins. This is the default pin implementation if the RPi.GPIO library is installed. Supports all features including PWM (via software).

Because this is the default pin implementation you can use it simply by specifying an integer number for the pin in most operations, e.g.:

from gpiozero import LED

led = LED(12)

However, you can also construct RPi.GPIO pins manually if you wish:

from gpiozero.pins.rpigpio import RPiGPIOFactory
from gpiozero import LED

factory = RPiGPIOFactory()
led = LED(12, pin_factory=factory)

class gpiozero.pins.rpigpio.RPiGPIOPin(factory, number)[source]¶: Extends LocalPiPin. Pin implementation for the RPi.GPIO library. See RPiGPIOFactory for more information.

lgpio¶

class gpiozero.pins.lgpio.LGPIOFactory(chip=0)[source]¶

Extends LocalPiFactory. Uses the lgpio library to interface to the local computer’s GPIO pins. The lgpio library simply talks to Linux gpiochip devices; it is not specific to the Raspberry Pi although this class is currently constructed under the assumption that it is running on a Raspberry Pi.

You can construct lgpio pins manually like so:

from gpiozero.pins.lgpio import LGPIOFactory
from gpiozero import LED

factory = LGPIOFactory(chip=0)
led = LED(12, pin_factory=factory)

The chip parameter to the factory constructor specifies which gpiochip device to attempt to open. It defaults to 0 and thus doesn’t normally need to be specified (the example above only includes it for completeness).

The lgpio library relies on access to the /dev/gpiochip* devices. If you run into issues, please check that your user has read/write access to the specific gpiochip device you are attempting to open (0 by default).

class gpiozero.pins.lgpio.LGPIOPin(factory, number)[source]¶: Extends LocalPiPin. Pin implementation for the lgpio library. See LGPIOFactory for more information.

RPIO¶

class gpiozero.pins.rpio.RPIOFactory[source]¶

Extends LocalPiFactory. Uses the RPIO library to interface to the Pi’s GPIO pins. This is the default pin implementation if the RPi.GPIO library is not installed, but RPIO is. Supports all features including PWM (hardware via DMA).

Note

Please note that at the time of writing, RPIO is only compatible with Pi 1’s; the Raspberry Pi 2 Model B is not supported. Also note that root access is required so scripts must typically be run with sudo.

You can construct RPIO pins manually like so:

from gpiozero.pins.rpio import RPIOFactory
from gpiozero import LED

factory = RPIOFactory()
led = LED(12, pin_factory=factory)

class gpiozero.pins.rpio.RPIOPin(factory, number)[source]¶: Extends LocalPiPin. Pin implementation for the RPIO library. See RPIOFactory for more information.

PiGPIO¶

class gpiozero.pins.pigpio.PiGPIOFactory(host=None, port=None)[source]¶

Extends PiFactory. Uses the pigpio library to interface to the Pi’s GPIO pins. The pigpio library relies on a daemon (pigpiod) to be running as root to provide access to the GPIO pins, and communicates with this daemon over a network socket.

While this does mean only the daemon itself should control the pins, the architecture does have several advantages:

Pins can be remote controlled from another machine (the other machine doesn’t even have to be a Raspberry Pi; it simply needs the pigpio client library installed on it)
The daemon supports hardware PWM via the DMA controller
Your script itself doesn’t require root privileges; it just needs to be able to communicate with the daemon

You can construct pigpio pins manually like so:

from gpiozero.pins.pigpio import PiGPIOFactory
from gpiozero import LED

factory = PiGPIOFactory()
led = LED(12, pin_factory=factory)

This is particularly useful for controlling pins on a remote machine. To accomplish this simply specify the host (and optionally port) when constructing the pin:

from gpiozero.pins.pigpio import PiGPIOFactory
from gpiozero import LED

factory = PiGPIOFactory(host='192.168.0.2')
led = LED(12, pin_factory=factory)

Note

In some circumstances, especially when playing with PWM, it does appear to be possible to get the daemon into “unusual” states. We would be most interested to hear any bug reports relating to this (it may be a bug in our pin implementation). A workaround for now is simply to restart the pigpiod daemon.

class gpiozero.pins.pigpio.PiGPIOPin(factory, number)[source]¶: Extends PiPin. Pin implementation for the pigpio library. See PiGPIOFactory for more information.

Native¶

class gpiozero.pins.native.NativeFactory[source]¶

Extends LocalPiFactory. Uses a built-in pure Python implementation to interface to the Pi’s GPIO pins. This is the default pin implementation if no third-party libraries are discovered.

Warning

This implementation does not currently support PWM. Attempting to use any class which requests PWM will raise an exception.

You can construct native pin instances manually like so:

from gpiozero.pins.native import NativeFactory
from gpiozero import LED

factory = NativeFactory()
led = LED(12, pin_factory=factory)

class gpiozero.pins.native.NativePin(factory, number)[source]¶: Extends LocalPiPin. Native pin implementation. See NativeFactory for more information.

class gpiozero.pins.native.Native2835Pin(factory, number)[source]¶: Extends NativePin for Pi hardware prior to the Pi 4 (Pi 0, 1, 2, 3, and 3+).

class gpiozero.pins.native.Native2711Pin(factory, number)[source]¶: Extends NativePin for Pi 4 hardware (Pi 4, CM4, Pi 400 at the time of writing).

Mock¶

class gpiozero.pins.mock.MockFactory(revision=None, pin_class=None)[source]¶

Factory for generating mock pins. The revision parameter specifies what revision of Pi the mock factory pretends to be (this affects the result of the pi_info attribute as well as where pull-ups are assumed to be). The pin_class attribute specifies which mock pin class will be generated by the pin() method by default. This can be changed after construction by modifying the pin_class attribute.

pin_class¶: This attribute stores the MockPin class (or descendent) that will be used when constructing pins with the pin() method (if no pin_class parameter is used to override it). It defaults on construction to the value of the pin_class parameter in the constructor, or MockPin if that is unspecified.

pin(spec, pin_class=None, **kwargs)[source]¶: The pin method for MockFactory additionally takes a pin_class attribute which can be used to override the class’ pin_class attribute. Any additional keyword arguments will be passed along to the pin constructor (useful with things like MockConnectedPin which expect to be constructed with another pin).

reset()[source]¶: Clears the pins and reservations sets. This is primarily useful in test suites to ensure the pin factory is back in a “clean” state before the next set of tests are run.

class gpiozero.pins.mock.MockPin(factory, number)[source]¶: A mock pin used primarily for testing. This class does not support PWM.

class gpiozero.pins.mock.MockPWMPin(factory, number)[source]¶: This derivative of MockPin adds PWM support.

class gpiozero.pins.mock.MockConnectedPin(factory, number, input_pin=None)[source]¶: This derivative of MockPin emulates a pin connected to another mock pin. This is used in the “real pins” portion of the test suite to check that one pin can influence another.

class gpiozero.pins.mock.MockChargingPin(factory, number, charge_time=0.01)[source]¶: This derivative of MockPin emulates a pin which, when set to input, waits a predetermined length of time and then drives itself high (as if attached to, e.g. a typical circuit using an LDR and a capacitor to time the charging rate).

class gpiozero.pins.mock.MockTriggerPin(factory, number, echo_pin=None, echo_time=0.04)[source]¶: This derivative of MockPin is intended to be used with another MockPin to emulate a distance sensor. Set echo_pin to the corresponding pin instance. When this pin is driven high it will trigger the echo pin to drive high for the echo time.

API - Exceptions¶

The following exceptions are defined by GPIO Zero. Please note that multiple inheritance is heavily used in the exception hierarchy to make testing for exceptions easier. For example, to capture any exception generated by GPIO Zero’s code:

from gpiozero import *

led = PWMLED(17)
try:
    led.value = 2
except GPIOZeroError:
    print('A GPIO Zero error occurred')

Since all GPIO Zero’s exceptions descend from GPIOZeroError, this will work. However, certain specific errors have multiple parents. For example, in the case that an out of range value is passed to OutputDevice.value you would expect a ValueError to be raised. In fact, a OutputDeviceBadValue error will be raised. However, note that this descends from both GPIOZeroError (indirectly) and from ValueError so you can still do the obvious:

from gpiozero import *

led = PWMLED(17)
try:
    led.value = 2
except ValueError:
    print('Bad value specified')

Errors¶

exception gpiozero.GPIOZeroError[source]¶

Bases: Exception

Base class for all exceptions in GPIO Zero

exception gpiozero.DeviceClosed[source]¶

Bases: gpiozero.exc.GPIOZeroError

Error raised when an operation is attempted on a closed device

exception gpiozero.BadEventHandler[source]¶

Bases: gpiozero.exc.GPIOZeroError, ValueError

Error raised when an event handler with an incompatible prototype is specified

exception gpiozero.BadWaitTime[source]¶

Bases: gpiozero.exc.GPIOZeroError, ValueError

Error raised when an invalid wait time is specified

exception gpiozero.BadQueueLen[source]¶

Bases: gpiozero.exc.GPIOZeroError, ValueError

Error raised when non-positive queue length is specified

exception gpiozero.BadPinFactory[source]¶

Bases: gpiozero.exc.GPIOZeroError, ImportError

Error raised when an unknown pin factory name is specified

exception gpiozero.ZombieThread[source]¶

Bases: gpiozero.exc.GPIOZeroError, RuntimeError

Error raised when a thread fails to die within a given timeout

exception gpiozero.CompositeDeviceError[source]¶

Bases: gpiozero.exc.GPIOZeroError

Base class for errors specific to the CompositeDevice hierarchy

exception gpiozero.CompositeDeviceBadName[source]¶

Bases: gpiozero.exc.CompositeDeviceError, ValueError

Error raised when a composite device is constructed with a reserved name

exception gpiozero.CompositeDeviceBadOrder[source]¶

Bases: gpiozero.exc.CompositeDeviceError, ValueError

Error raised when a composite device is constructed with an incomplete order

exception gpiozero.CompositeDeviceBadDevice[source]¶

Bases: gpiozero.exc.CompositeDeviceError, ValueError

Error raised when a composite device is constructed with an object that doesn’t inherit from Device

exception gpiozero.EnergenieSocketMissing[source]¶

Bases: gpiozero.exc.CompositeDeviceError, ValueError

Error raised when socket number is not specified

exception gpiozero.EnergenieBadSocket[source]¶

Bases: gpiozero.exc.CompositeDeviceError, ValueError

Error raised when an invalid socket number is passed to Energenie

exception gpiozero.SPIError[source]¶

Bases: gpiozero.exc.GPIOZeroError

Base class for errors related to the SPI implementation

exception gpiozero.SPIBadArgs[source]¶

Bases: gpiozero.exc.SPIError, ValueError

Error raised when invalid arguments are given while constructing SPIDevice

exception gpiozero.SPIBadChannel[source]¶

Bases: gpiozero.exc.SPIError, ValueError

Error raised when an invalid channel is given to an AnalogInputDevice

exception gpiozero.SPIFixedClockMode[source]¶

Bases: gpiozero.exc.SPIError, AttributeError

Error raised when the SPI clock mode cannot be changed

exception gpiozero.SPIInvalidClockMode[source]¶

Bases: gpiozero.exc.SPIError, ValueError

Error raised when an invalid clock mode is given to an SPI implementation

exception gpiozero.SPIFixedBitOrder[source]¶

Bases: gpiozero.exc.SPIError, AttributeError

Error raised when the SPI bit-endianness cannot be changed

exception gpiozero.SPIFixedSelect[source]¶

Bases: gpiozero.exc.SPIError, AttributeError

Error raised when the SPI select polarity cannot be changed

exception gpiozero.SPIFixedWordSize[source]¶

Bases: gpiozero.exc.SPIError, AttributeError

Error raised when the number of bits per word cannot be changed

exception gpiozero.SPIInvalidWordSize[source]¶

Bases: gpiozero.exc.SPIError, ValueError

Error raised when an invalid (out of range) number of bits per word is specified

exception gpiozero.GPIODeviceError[source]¶

Bases: gpiozero.exc.GPIOZeroError

Base class for errors specific to the GPIODevice hierarchy

exception gpiozero.GPIODeviceClosed[source]¶

Bases: gpiozero.exc.GPIODeviceError, gpiozero.exc.DeviceClosed

Deprecated descendent of DeviceClosed

exception gpiozero.GPIOPinInUse[source]¶

Bases: gpiozero.exc.GPIODeviceError

Error raised when attempting to use a pin already in use by another device

exception gpiozero.GPIOPinMissing[source]¶

Bases: gpiozero.exc.GPIODeviceError, ValueError

Error raised when a pin specification is not given

exception gpiozero.InputDeviceError[source]¶

Bases: gpiozero.exc.GPIODeviceError

Base class for errors specific to the InputDevice hierarchy

exception gpiozero.OutputDeviceError[source]¶

Bases: gpiozero.exc.GPIODeviceError

Base class for errors specified to the OutputDevice hierarchy

exception gpiozero.OutputDeviceBadValue[source]¶

Bases: gpiozero.exc.OutputDeviceError, ValueError

Error raised when value is set to an invalid value

exception gpiozero.PinError[source]¶

Bases: gpiozero.exc.GPIOZeroError

Base class for errors related to pin implementations

exception gpiozero.PinInvalidFunction[source]¶

Bases: gpiozero.exc.PinError, ValueError

Error raised when attempting to change the function of a pin to an invalid value

exception gpiozero.PinInvalidState[source]¶

Bases: gpiozero.exc.PinError, ValueError

Error raised when attempting to assign an invalid state to a pin

exception gpiozero.PinInvalidPull[source]¶

Bases: gpiozero.exc.PinError, ValueError

Error raised when attempting to assign an invalid pull-up to a pin

exception gpiozero.PinInvalidEdges[source]¶

Bases: gpiozero.exc.PinError, ValueError

Error raised when attempting to assign an invalid edge detection to a pin

exception gpiozero.PinInvalidBounce[source]¶

Bases: gpiozero.exc.PinError, ValueError

Error raised when attempting to assign an invalid bounce time to a pin

exception gpiozero.PinSetInput[source]¶

Bases: gpiozero.exc.PinError, AttributeError

Error raised when attempting to set a read-only pin

exception gpiozero.PinFixedPull[source]¶

Bases: gpiozero.exc.PinError, AttributeError

Error raised when attempting to set the pull of a pin with fixed pull-up

exception gpiozero.PinEdgeDetectUnsupported[source]¶

Bases: gpiozero.exc.PinError, AttributeError

Error raised when attempting to use edge detection on unsupported pins

exception gpiozero.PinUnsupported[source]¶

Bases: gpiozero.exc.PinError, NotImplementedError

Error raised when attempting to obtain a pin interface on unsupported pins

exception gpiozero.PinSPIUnsupported[source]¶

Bases: gpiozero.exc.PinError, NotImplementedError

Error raised when attempting to obtain an SPI interface on unsupported pins

exception gpiozero.PinPWMError[source]¶

Bases: gpiozero.exc.PinError

Base class for errors related to PWM implementations

exception gpiozero.PinPWMUnsupported[source]¶

Bases: gpiozero.exc.PinPWMError, AttributeError

Error raised when attempting to activate PWM on unsupported pins

exception gpiozero.PinPWMFixedValue[source]¶

Bases: gpiozero.exc.PinPWMError, AttributeError

Error raised when attempting to initialize PWM on an input pin

exception gpiozero.PinUnknownPi[source]¶

Bases: gpiozero.exc.PinError, RuntimeError

Error raised when gpiozero doesn’t recognize a revision of the Pi

exception gpiozero.PinMultiplePins[source]¶

Bases: gpiozero.exc.PinError, RuntimeError

Error raised when multiple pins support the requested function

exception gpiozero.PinNoPins[source]¶

Bases: gpiozero.exc.PinError, RuntimeError

Error raised when no pins support the requested function

exception gpiozero.PinInvalidPin[source]¶

Bases: gpiozero.exc.PinError, ValueError

Error raised when an invalid pin specification is provided

Warnings¶

exception gpiozero.GPIOZeroWarning[source]¶

Bases: Warning

Base class for all warnings in GPIO Zero

exception gpiozero.DistanceSensorNoEcho[source]¶

Bases: gpiozero.exc.GPIOZeroWarning

Warning raised when the distance sensor sees no echo at all

exception gpiozero.SPIWarning[source]¶

Bases: gpiozero.exc.GPIOZeroWarning

Base class for warnings related to the SPI implementation

exception gpiozero.SPISoftwareFallback[source]¶

Bases: gpiozero.exc.SPIWarning

Warning raised when falling back to the SPI software implementation

exception gpiozero.PinWarning[source]¶

Bases: gpiozero.exc.GPIOZeroWarning

Base class for warnings related to pin implementations

exception gpiozero.PinFactoryFallback[source]¶

Bases: gpiozero.exc.PinWarning

Warning raised when a default pin factory fails to load and a fallback is tried

exception gpiozero.PinNonPhysical[source]¶

Bases: gpiozero.exc.PinWarning

Warning raised when a non-physical pin is specified in a constructor

exception gpiozero.ThresholdOutOfRange[source]¶

Bases: gpiozero.exc.GPIOZeroWarning

Warning raised when a threshold is out of range specified by min and max values

exception gpiozero.CallbackSetToNone[source]¶

Bases: gpiozero.exc.GPIOZeroWarning

Warning raised when a callback is set to None when its previous value was None

Changelog¶

Release 1.6.1 (2021-03-17)¶

Fix missing font files for 7-segment displays

Release 1.6.0 (2021-03-14)¶

Added RotaryEncoder class (thanks to Paulo Mateus) (#482, #928)
Added support for multi-segment character displays with LEDCharDisplay and LEDMultiCharDisplay along with “font” support using LEDCharFont (thanks to Martin O’Hanlon) (#357, #485, #488, #493, #930)
Added Pibrella class (thanks to Carl Monk) (#773, #798)
Added TrafficpHat class (thanks to Ryan Walmsley) (#845, #846)
Added support for the lgpio library as a pin factory (LGPIOFactory) (thanks to Joan for lg) (#927)
Allow Motor to pass pin_factory to its child OutputDevice objects (thanks to Yisrael Dov Lebow) (#792)
Small SPI exception fix (thanks to Maksim Levental) (#762)
Warn users when using default pin factory for Servos and Distance Sensors (thanks to Sofiia Kosovan and Daniele Procida at the EuroPython sprints) (#780, #781)
Added pulse_width property to Servo (suggested by Daniele Procida at the PyCon UK sprints) (#795, #797)
Added event-driven functionality to internal devices (#941)
Allowed Energenie sockets preserve their state on construction (thanks to Jack Wearden) (#865)
Added source tools scaled_half() and scaled_full()
Added complete Pi 4 support to NativeFactory (thanks to Andrew Scheller) (#920, #929, #940)
Updated add-on boards to use BOARD numbering (#349, #860)
Fixed ButtonBoard release events (#761)
Add ASCII art diagrams to pinout for Pi 400 and CM4 (#932)
Cleaned up software SPI (thanks to Andrew Scheller and Kyle Morgan) (#777, #895, #900)
Added USB3 and Ethernet speed attributes to pi_info()
Various docs updates

Warning

This is the last release to support Python 2

Release 1.5.1 (2019-06-24)¶

Added Raspberry Pi 4 data for pi_info() and pinout
Minor docs updates

Release 1.5.0 (2019-02-12)¶

Introduced pin event timing to increase accuracy of certain devices such as the HC-SR04 DistanceSensor. (#664, #665)
Further improvements to DistanceSensor (ignoring missed edges). (#719)
Allow source to take a device object as well as values or other values. See Source/Values. (#640)
Added internal device classes LoadAverage and DiskUsage (thanks to Jeevan M R for the latter). (#532, #714)
Added support for colorzero with RGBLED (this adds a new dependency). (#655)
Added TonalBuzzer with Tone API for specifying frequencies raw or via MIDI or musical notes. (#681, #717)
Added PiHutXmasTree. (#502)
Added PumpkinPi and JamHat (thanks to Claire Pollard). (#680, #681, #717)
Ensured gpiozero can be imported without a valid pin factory set. (#591, #713)
Reduced import time by not computing default pin factory at the point of import. (#675, #722)
Added support for various pin numbering mechanisms. (#470)
Motor instances now use DigitalOutputDevice for non-PWM pins.
Allow non-PWM use of Robot. (#481)
Added optional enable init param to Motor. (#366)
Added --xyz option to pinout command line tool to open pinout.xyz in a web browser. (#604)
Added 3B+, 3A+ and CM3+ to Pi model data. (#627, #704)
Minor improvements to Energenie, thanks to Steve Amor. (#629, #634)
Allow SmoothedInputDevice, LightSensor and MotionSensor to have pull-up configured. (#652)
Allow input devices to be pulled up or down externally, thanks to Philippe Muller. (#593, #658)
Minor changes to support Python 3.7, thanks to Russel Winder and Rick Ansell. (#666, #668, #669, #671, #673)
Added zip_values() source tool.
Correct row/col numbering logic in PinInfo. (#674)
Many additional tests, and other improvements to the test suite.
Many documentation corrections, additions and clarifications.
Automatic documentation class hierarchy diagram generation.
Automatic copyright attribution in source files.

Release 1.4.1 (2018-02-20)¶

This release is mostly bug-fixes, but a few enhancements have made it in too:

Added curve_left and curve_right parameters to Robot.forward() and Robot.backward(). (#306 and #619)
Fixed DistanceSensor returning incorrect readings after a long pause, and added a lock to ensure multiple distance sensors can operate simultaneously in a single project. (#584, #595, #617, #618)
Added support for phase/enable motor drivers with PhaseEnableMotor, PhaseEnableRobot, and descendants, thanks to Ian Harcombe! (#386)
A variety of other minor enhancements, largely thanks to Andrew Scheller! (#479, #489, #491, #492)

Release 1.4.0 (2017-07-26)¶

Pin factory is now configurable from device constructors as well as command line. NOTE: this is a backwards incompatible change for manual pin construction but it’s hoped this is (currently) a sufficiently rare use case that this won’t affect too many people and the benefits of the new system warrant such a change, i.e. the ability to use remote pin factories with HAT classes that don’t accept pin assignations (#279)
Major work on SPI, primarily to support remote hardware SPI (#421, #459, #465, #468, #575)
Pin reservation now works properly between GPIO and SPI devices (#459, #468)
Lots of work on the documentation: source/values chapter, better charts, more recipes, remote GPIO configuration, mock pins, better PDF output (#484, #469, #523, #520, #434, #565, #576)
Support for StatusZero and StatusBoard HATs (#558)
Added pinout command line tool to provide a simple reference to the GPIO layout and information about the associated Pi (#497, #504) thanks to Stewart Adcock for the initial work
pi_info() made more lenient for new (unknown) Pi models (#529)
Fixed a variety of packaging issues (#535, #518, #519)
Improved text in factory fallback warnings (#572)

Release 1.3.2 (2017-03-03)¶

Added new Pi models to stop pi_info() breaking
Fix issue with pi_info() breaking on unknown Pi models

Release 1.3.1 (2016-08-31 … later)¶

Fixed hardware SPI support which Dave broke in 1.3.0. Sorry!
Some minor docs changes

Release 1.3.0 (2016-08-31)¶

Added ButtonBoard for reading multiple buttons in a single class (#340)
Added Servo and AngularServo classes for controlling simple servo motors (#248)
Lots of work on supporting easier use of internal and third-party pin implementations (#359)
Robot now has a proper value attribute (#305)
Added CPUTemperature as another demo of “internal” devices (#294)
A temporary work-around for an issue with DistanceSensor was included but a full fix is in the works (#385)
More work on the documentation (#320, #295, #289, etc.)

Not quite as much as we’d hoped to get done this time, but we’re rushing to make a Raspbian freeze. As always, thanks to the community - your suggestions and PRs have been brilliant and even if we don’t take stuff exactly as is, it’s always great to see your ideas. Onto 1.4!

Release 1.2.0 (2016-04-10)¶

Added Energenie class for controlling Energenie plugs (#69)
Added LineSensor class for single line-sensors (#109)
Added DistanceSensor class for HC-SR04 ultra-sonic sensors (#114)
Added SnowPi class for the Ryanteck Snow-pi board (#130)
Added when_held (and related properties) to Button (#115)
Fixed issues with installing GPIO Zero for python 3 on Raspbian Wheezy releases (#140)
Added support for lots of ADC chips (MCP3xxx family) (#162) - many thanks to pcopa and lurch!
Added support for pigpiod as a pin implementation with PiGPIOPin (#180)
Many refinements to the base classes mean more consistency in composite devices and several bugs squashed (#164, #175, #182, #189, #193, #229)
GPIO Zero is now aware of what sort of Pi it’s running on via pi_info() and has a fairly extensive database of Pi information which it uses to determine when users request impossible things (like pull-down on a pin with a physical pull-up resistor) (#222)
The source/values system was enhanced to ensure normal usage doesn’t stress the CPU and lots of utilities were added (#181, #251)

And I’ll just add a note of thanks to the many people in the community who contributed to this release: we’ve had some great PRs, suggestions, and bug reports in this version. Of particular note:

Schelto van Doorn was instrumental in adding support for numerous ADC chips
Alex Eames generously donated a RasPiO Analog board which was extremely useful in developing the software SPI interface (and testing the ADC support)
Andrew Scheller squashed several dozen bugs (usually a day or so after Dave had introduced them ;)

As always, many thanks to the whole community - we look forward to hearing from you more in 1.3!

Release 1.1.0 (2016-02-08)¶

Documentation converted to reST and expanded to include generic classes and several more recipes (#80, #82, #101, #119, #135, #168)
New CamJamKitRobot class with the pre-defined motor pins for the new CamJam EduKit
New LEDBarGraph class (many thanks to Martin O’Hanlon!) (#126, #176)
New Pin implementation abstracts out the concept of a GPIO pin paving the way for alternate library support and IO extenders in future (#141)
New LEDBoard.blink() method which works properly even when background is set to False (#94, #161)
New RGBLED.blink() method which implements (rudimentary) color fading too! (#135, #174)
New initial_value attribute on OutputDevice ensures consistent behaviour on construction (#118)
New active_high attribute on PWMOutputDevice and RGBLED allows use of common anode devices (#143, #154)
Loads of new ADC chips supported (many thanks to GitHub user pcopa!) (#150)

Release 1.0.0 (2015-11-16)¶

Debian packaging added (#44)
PWMLED class added (#58)
TemperatureSensor removed pending further work (#93)
Buzzer.beep() alias method added (#75)
Motor PWM devices exposed, and Robot motor devices exposed (#107)

Release 0.9.0 (2015-10-25)¶

Fourth public beta

Added source and values properties to all relevant classes (#76)
Fix names of parameters in Motor constructor (#79)
Added wrappers for LED groups on add-on boards (#81)

Release 0.8.0 (2015-10-16)¶

Third public beta

Added generic AnalogInputDevice class along with specific classes for the MCP3008 and MCP3004 (#41)
Fixed DigitalOutputDevice.blink() (#57)

Release 0.7.0 (2015-10-09)¶

Second public beta

Release 0.6.0 (2015-09-28)¶

First public beta

Release 0.5.0 (2015-09-24)¶

Release 0.4.0 (2015-09-23)¶

Release 0.3.0 (2015-09-22)¶

Release 0.2.0 (2015-09-21)¶

Initial release

License¶

SPDX-License-Identifier: BSD-3-Clause

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
Neither the name of the copyright holder nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS “AS IS” AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.