5. 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!
5.1. LED + Button¶
Let a button on one Raspberry Pi control the LED of another:
from gpiozero import 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.values
pause()
5.2. LED + 2 Buttons¶
The LED will come on when both buttons are pressed:
from gpiozero import 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.values, button_2.values)
pause()
5.3. Multi-room motion alert¶
Install a Raspberry Pi with a motion sensor in each room of your house, and have an LED indicator showing when there’s motion in each room:
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]
leds = LEDBoard(2, 3, 4, 5) # leds on this pi
sensors = [MotionSensor(17, pin_factory=r) for r in remotes] # remote sensors
for led, sensor in zip(leds, sensors):
led.source = sensor.values
pause()
5.4. 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.values
pause()
This could also be used as an internal doorbell (tell people it’s time for dinner from the kitchen).
5.5. 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()
5.6. 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 light sensor 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.