from __future__ import (
unicode_literals,
print_function,
absolute_import,
division,
)
import warnings
from time import sleep
from threading import Lock
from itertools import repeat, cycle, chain
from .exc import OutputDeviceError, GPIODeviceError, GPIODeviceClosed
from .devices import GPIODevice, GPIOThread, CompositeDevice, SourceMixin
[docs]class OutputDevice(SourceMixin, GPIODevice):
"""
Represents a generic GPIO output device.
This class extends :class:`GPIODevice` to add facilities common to GPIO
output devices: an :meth:`on` method to switch the device on, and a
corresponding :meth:`off` method.
:param int pin:
The GPIO pin (in BCM numbering) that the device is connected to. If
this is ``None`` a :exc:`GPIODeviceError` will be raised.
:param bool active_high:
If ``True`` (the default), the :meth:`on` method will set the GPIO to
HIGH. If ``False``, the :meth:`on` method will set the GPIO to LOW (the
:meth:`off` method always does the opposite).
:param bool initial_value:
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.
"""
def __init__(self, pin=None, active_high=True, initial_value=False):
self._active_high = active_high
super(OutputDevice, self).__init__(pin)
self._active_state = True if active_high else False
self._inactive_state = False if active_high else True
if initial_value is None:
self.pin.function = 'output'
elif initial_value:
self.pin.output_with_state(self._active_state)
else:
self.pin.output_with_state(self._inactive_state)
def _write(self, value):
if not self.active_high:
value = not value
try:
self.pin.state = bool(value)
except ValueError:
self._check_open()
raise
[docs] def on(self):
"""
Turns the device on.
"""
self._write(True)
[docs] def off(self):
"""
Turns the device off.
"""
self._write(False)
@property
def value(self):
return super(OutputDevice, self).value
@value.setter
def value(self, value):
self._write(value)
@property
def active_high(self):
return self._active_high
def __repr__(self):
try:
return '<gpiozero.%s object on pin %r, active_high=%s, is_active=%s>' % (
self.__class__.__name__, self.pin, self.active_high, self.is_active)
except:
return super(OutputDevice, self).__repr__()
[docs]class DigitalOutputDevice(OutputDevice):
"""
Represents a generic output device with typical on/off behaviour.
This class extends :class:`OutputDevice` with a :meth:`toggle` method to
switch the device between its on and off states, and a :meth:`blink` method
which uses an optional background thread to handle toggling the device
state without further interaction.
"""
def __init__(self, pin=None, active_high=True, initial_value=False):
self._blink_thread = None
super(DigitalOutputDevice, self).__init__(pin, active_high, initial_value)
self._lock = Lock()
[docs] def close(self):
self._stop_blink()
super(DigitalOutputDevice, self).close()
[docs] def on(self):
self._stop_blink()
self._write(True)
[docs] def off(self):
self._stop_blink()
self._write(False)
[docs] def toggle(self):
"""
Reverse the state of the device. If it's on, turn it off; if it's off,
turn it on.
"""
with self._lock:
if self.is_active:
self.off()
else:
self.on()
[docs] def blink(self, on_time=1, off_time=1, n=None, background=True):
"""
Make the device turn on and off repeatedly.
:param float on_time:
Number of seconds on. Defaults to 1 second.
:param float off_time:
Number of seconds off. Defaults to 1 second.
:param int n:
Number of times to blink; ``None`` (the default) means forever.
:param bool background:
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).
"""
self._stop_blink()
self._blink_thread = GPIOThread(
target=self._blink_device, args=(on_time, off_time, n)
)
self._blink_thread.start()
if not background:
self._blink_thread.join()
self._blink_thread = None
def _stop_blink(self):
if self._blink_thread:
self._blink_thread.stop()
self._blink_thread = None
def _blink_device(self, on_time, off_time, n):
iterable = repeat(0) if n is None else repeat(0, n)
for i in iterable:
self._write(True)
if self._blink_thread.stopping.wait(on_time):
break
self._write(False)
if self._blink_thread.stopping.wait(off_time):
break
[docs]class LED(DigitalOutputDevice):
"""
Extends :class:`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()
:param int pin:
The GPIO pin which the LED is attached to. See :doc:`notes` for valid
pin numbers.
:param bool active_high:
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).
:param bool initial_value:
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.
"""
pass
LED.is_lit = LED.is_active
[docs]class Buzzer(DigitalOutputDevice):
"""
Extends :class:`DigitalOutputDevice` and represents a digital buzzer
component.
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()
:param int pin:
The GPIO pin which the buzzer is attached to. See :doc:`notes` for
valid pin numbers.
:param bool active_high:
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.
:param bool initial_value:
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.
"""
pass
Buzzer.beep = Buzzer.blink
[docs]class PWMOutputDevice(OutputDevice):
"""
Generic output device configured for pulse-width modulation (PWM).
:param int pin:
The GPIO pin which the device is attached to. See :doc:`notes` for
valid pin numbers.
:param bool active_high:
If ``True`` (the default), the :meth:`on` method will set the GPIO to
HIGH. If ``False``, the :meth:`on` method will set the GPIO to LOW (the
:meth:`off` method always does the opposite).
:param bool initial_value:
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.
:param int frequency:
The frequency (in Hz) of pulses emitted to drive the device. Defaults
to 100Hz.
"""
def __init__(self, pin=None, active_high=True, initial_value=0, frequency=100):
self._blink_thread = None
if not 0 <= initial_value <= 1:
raise OutputDeviceError("initial_value must be between 0 and 1")
super(PWMOutputDevice, self).__init__(pin, active_high)
try:
# XXX need a way of setting these together
self.pin.frequency = frequency
self.value = initial_value
except:
self.close()
raise
[docs] def close(self):
self._stop_blink()
try:
self.pin.frequency = None
except AttributeError:
# If the pin's already None, ignore the exception
pass
super(PWMOutputDevice, self).close()
def _read(self):
self._check_open()
if self.active_high:
return self.pin.state
else:
return 1 - self.pin.state
def _write(self, value):
if not self.active_high:
value = 1 - value
if not 0 <= value <= 1:
raise OutputDeviceError("PWM value must be between 0 and 1")
try:
self.pin.state = value
except AttributeError:
self._check_open()
raise
@property
def value(self):
"""
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.
"""
return self._read()
@value.setter
def value(self, value):
self._stop_blink()
self._write(value)
[docs] def on(self):
self._stop_blink()
self._write(1)
[docs] def off(self):
self._stop_blink()
self._write(0)
[docs] def toggle(self):
"""
Toggle the state of the device. If the device is currently off
(:attr:`value` is 0.0), this changes it to "fully" on (:attr:`value` is
1.0). If the device has a duty cycle (:attr:`value`) of 0.1, this will
toggle it to 0.9, and so on.
"""
self._stop_blink()
self.value = 1 - self.value
@property
def is_active(self):
"""
Returns ``True`` if the device is currently active (:attr:`value` is
non-zero) and ``False`` otherwise.
"""
return self.value != 0
@property
def frequency(self):
"""
The frequency of the pulses used with the PWM device, in Hz. The
default is 100Hz.
"""
return self.pin.frequency
@frequency.setter
def frequency(self, value):
self.pin.frequency = value
[docs] def blink(
self, 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.
:param float on_time:
Number of seconds on. Defaults to 1 second.
:param float off_time:
Number of seconds off. Defaults to 1 second.
:param float fade_in_time:
Number of seconds to spend fading in. Defaults to 0.
:param float fade_out_time:
Number of seconds to spend fading out. Defaults to 0.
:param int n:
Number of times to blink; ``None`` (the default) means forever.
:param bool background:
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).
"""
self._stop_blink()
self._blink_thread = GPIOThread(
target=self._blink_device,
args=(on_time, off_time, fade_in_time, fade_out_time, n)
)
self._blink_thread.start()
if not background:
self._blink_thread.join()
self._blink_thread = None
def _stop_blink(self):
if self._blink_thread:
self._blink_thread.stop()
self._blink_thread = None
def _blink_device(
self, on_time, off_time, fade_in_time, fade_out_time, n, fps=50):
sequence = []
if fade_in_time > 0:
sequence += [
(i * (1 / fps) / fade_in_time, 1 / fps)
for i in range(int(fps * fade_in_time))
]
sequence.append((1, on_time))
if fade_out_time > 0:
sequence += [
(1 - (i * (1 / fps) / fade_out_time), 1 / fps)
for i in range(int(fps * fade_out_time))
]
sequence.append((0, off_time))
sequence = (
cycle(sequence) if n is None else
chain.from_iterable(repeat(sequence, n))
)
for value, delay in sequence:
self._write(value)
if self._blink_thread.stopping.wait(delay):
break
[docs]class PWMLED(PWMOutputDevice):
"""
Extends :class:`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.
:param int pin:
The GPIO pin which the LED is attached to. See :doc:`notes` for
valid pin numbers.
:param bool active_high:
If ``True`` (the default), the :meth:`on` method will set the GPIO to
HIGH. If ``False``, the :meth:`on` method will set the GPIO to LOW (the
:meth:`off` method always does the opposite).
:param bool initial_value:
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.
:param int frequency:
The frequency (in Hz) of pulses emitted to drive the LED. Defaults
to 100Hz.
"""
pass
PWMLED.is_lit = PWMLED.is_active
def _led_property(index, doc=None):
def getter(self):
return self._leds[index].value
def setter(self, value):
self._stop_blink()
self._leds[index].value = value
return property(getter, setter, doc=doc)
[docs]class RGBLED(SourceMixin, CompositeDevice):
"""
Extends :class:`CompositeDevice` 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 can either use three limiting resistors (one per anode) or a
single limiting resistor on the cathode.
The following code will make the LED purple::
from gpiozero import RGBLED
led = RGBLED(2, 3, 4)
led.color = (1, 0, 1)
:param int red:
The GPIO pin that controls the red component of the RGB LED.
:param int green:
The GPIO pin that controls the green component of the RGB LED.
:param int blue:
The GPIO pin that controls the blue component of the RGB LED.
:param bool active_high:
Set to ``True`` (the default) for common cathode RGB LEDs. If you are
using a common anode RGB LED, set this to ``False``.
:param bool initial_value:
The initial color for the LED. Defaults to black ``(0, 0, 0)``.
"""
def __init__(
self, red=None, green=None, blue=None, active_high=True,
initial_value=(0, 0, 0)):
self._leds = ()
self._blink_thread = None
if not all([red, green, blue]):
raise OutputDeviceError('red, green, and blue pins must be provided')
super(RGBLED, self).__init__()
self._leds = tuple(PWMLED(pin, active_high) for pin in (red, green, blue))
self.value = initial_value
red = _led_property(0)
green = _led_property(1)
blue = _led_property(2)
@property
def value(self):
"""
Represents the color of the LED as an RGB 3-tuple of ``(red, green,
blue)`` where each value is between 0 and 1.
For example, purple would be ``(1, 0, 1)`` and yellow would be ``(1, 1,
0)``, while orange would be ``(1, 0.5, 0)``.
"""
return (self.red, self.green, self.blue)
@value.setter
def value(self, value):
self.red, self.green, self.blue = value
@property
def is_active(self):
"""
Returns ``True`` if the LED is currently active (not black) and
``False`` otherwise.
"""
return self.value != (0, 0, 0)
is_lit = is_active
color = value
[docs] def on(self):
"""
Turn the LED on. This equivalent to setting the LED color to white
``(1, 1, 1)``.
"""
self.value = (1, 1, 1)
[docs] def off(self):
"""
Turn the LED off. This is equivalent to setting the LED color to black
``(0, 0, 0)``.
"""
self.value = (0, 0, 0)
[docs] def toggle(self):
"""
Toggle the state of the device. If the device is currently off
(:attr:`value` is ``(0, 0, 0)``), this changes it to "fully" on
(:attr:`value` is ``(1, 1, 1)``). If the device has a specific color,
this method inverts the color.
"""
r, g, b = self.value
self.value = (1 - r, 1 - g, 1 - b)
def close(self):
self._stop_blink()
for led in self._leds:
led.close()
[docs] def blink(
self, 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):
"""
Make the device turn on and off repeatedly.
:param float on_time:
Number of seconds on. Defaults to 1 second.
:param float off_time:
Number of seconds off. Defaults to 1 second.
:param float fade_in_time:
Number of seconds to spend fading in. Defaults to 0.
:param float fade_out_time:
Number of seconds to spend fading out. Defaults to 0.
:param tuple on_color:
The color to use when the LED is "on". Defaults to white.
:param tuple off_color:
The color to use when the LED is "off". Defaults to black.
:param int n:
Number of times to blink; ``None`` (the default) means forever.
:param bool background:
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).
"""
self._stop_blink()
self._blink_thread = GPIOThread(
target=self._blink_device,
args=(on_time, off_time, fade_in_time, fade_out_time, on_color, off_color, n)
)
self._blink_thread.start()
if not background:
self._blink_thread.join()
self._blink_thread = None
def _stop_blink(self):
if self._blink_thread:
self._blink_thread.stop()
self._blink_thread = None
def _blink_device(
self, on_time, off_time, fade_in_time, fade_out_time, on_color,
off_color, n, fps=50):
# Define some simple lambdas to perform linear interpolation between
# off_color and on_color
lerp = lambda t, fade_in: tuple(
(1 - t) * off + t * on
if fade_in else
(1 - t) * on + t * off
for off, on in zip(off_color, on_color)
)
sequence = []
if fade_in_time > 0:
sequence += [
(lerp(i * (1 / fps) / fade_in_time, True), 1 / fps)
for i in range(int(fps * fade_in_time))
]
sequence.append((on_color, on_time))
if fade_out_time > 0:
sequence += [
(lerp(i * (1 / fps) / fade_out_time, False), 1 / fps)
for i in range(int(fps * fade_out_time))
]
sequence.append((off_color, off_time))
sequence = (
cycle(sequence) if n is None else
chain.from_iterable(repeat(sequence, n))
)
for value, delay in sequence:
self._leds[0].value, self._leds[1].value, self._leds[2].value = value
if self._blink_thread.stopping.wait(delay):
break
[docs]class Motor(SourceMixin, CompositeDevice):
"""
Extends :class:`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.
.. _H-bridge: https://en.wikipedia.org/wiki/H_bridge
The following code will make the motor turn "forwards"::
from gpiozero import Motor
motor = Motor(17, 18)
motor.forward()
:param int forward:
The GPIO pin that the forward input of the motor driver chip is
connected to.
:param int backward:
The GPIO pin that the backward input of the motor driver chip is
connected to.
"""
def __init__(self, forward=None, backward=None):
if not all([forward, backward]):
raise OutputDeviceError(
'forward and backward pins must be provided'
)
super(Motor, self).__init__()
self._forward = PWMOutputDevice(forward)
self._backward = PWMOutputDevice(backward)
def close(self):
self._forward.close()
self._backward.close()
@property
def closed(self):
return self._forward.closed and self._backward.closed
@property
def forward_device(self):
"""
Returns the `PWMOutputDevice` representing the forward pin of the motor
controller.
"""
return self._forward
@property
def backward_device(self):
"""
Returns the `PWMOutputDevice` representing the backward pin of the
motor controller.
"""
return self._backward
@property
def value(self):
"""
Represents the speed of the motor as a floating point value between -1
(full speed backward) and 1 (full speed forward).
"""
return self._forward.value - self._backward.value
@value.setter
def value(self, value):
if not -1 <= value <= 1:
raise OutputDeviceError("Motor value must be between -1 and 1")
if value > 0:
self.forward(value)
elif value < 0:
self.backward(-value)
else:
self.stop()
@property
def is_active(self):
"""
Returns ``True`` if the motor is currently running and ``False``
otherwise.
"""
return self.value != 0
[docs] def forward(self, speed=1):
"""
Drive the motor forwards.
:param float speed:
The speed at which the motor should turn. Can be any value between
0 (stopped) and the default 1 (maximum speed).
"""
self._backward.off()
self._forward.value = speed
[docs] def backward(self, speed=1):
"""
Drive the motor backwards.
:param float speed:
The speed at which the motor should turn. Can be any value between
0 (stopped) and the default 1 (maximum speed).
"""
self._forward.off()
self._backward.value = speed
def reverse(self):
"""
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.
"""
self.value = -self.value
[docs] def stop(self):
"""
Stop the motor.
"""
self._forward.off()
self._backward.off()