gpiozero¶

A simple interface to everyday GPIO components used with Raspberry Pi.

Created by Ben Nuttall of the Raspberry Pi Foundation, Dave Jones, and other contributors.

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()

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.

Install¶

First, update your repositories list:

sudo apt-get update

Then install the package of your choice. Both Python 3 and Python 2 are supported. Python 3 is recommended:

sudo apt-get install python3-gpiozero

or:

sudo apt-get install python-gpiozero

Documentation¶

Comprehensive documentation is available at https://gpiozero.readthedocs.org/.

Development¶

This project is being developed on GitHub. Join in:

Provide suggestions, report bugs and ask questions as issues
Provide examples we can use as recipes
Contribute to the code

Alternatively, email suggestions and feedback to mailto:ben@raspberrypi.org

Contributors¶

Table of Contents¶

Recipes¶

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

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.

Any pin marked GPIO in the diagram below can be used for generic components:

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 Keep your script running for more information.

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()

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.values

pause()

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)

with PiCamera() as camera:
    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()

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

buttons = [Button(pin) for pin in sound_pins]
for button in buttons:
    sound = sound_pins[button.pin.number]
    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()

RGB LED¶

Making colours with an RGBLED:

from gpiozero import RGBLED
from time import sleep

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, LED
from signal import pause

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

led.source = sensor.values

pause()

Distance sensor¶

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()

Motors¶

Spin a Motor around forwards and backwards:

from gpiozero import Motor
from time import sleep

motor = Motor(forward=4, back=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 RyanteckRobot, Button
from signal import pause

robot = RyanteckRobot()

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 RyanteckRobot

robot = RyanteckRobot()

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 DOWN
            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 UP
            robot.stop()

curses.wrapper(main)

Note

This recipe uses the 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, but will require that you install the evdev library with sudo pip install evdev first:

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

robot = RyanteckRobot()

devices = [InputDevice(device) for device in list_devices()]
keyboard = devices[0]  # this may vary

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:
        if event.value == 1:  # key down
            keypress_actions[event.code]()
        if event.value == 0:  # key up
            robot.stop()

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 signal import pause

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

robot.source = zip(pir.values, pir.values)

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

while True:
    with MCP3008(channel=0) as pot:
        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.values
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 signal import pause

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

led.source = zip(red_pot.values, green_pot.values, blue_pot.values)

pause()

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

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)
activity = LED(47)

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

Notes¶

Keep your 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 or IDLE) shell. 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()

Importing from 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)

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. See the Recipes page for more information.

Button¶

class gpiozero.Button(pin, pull_up=True, bounce_time=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) – The GPIO pin which the button is attached to. See Notes for valid pin numbers.
pull_up (bool) – 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.
bounce_time (float) – If None (the default), no software bounce compensation will be performed. Otherwise, this is the length in 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.
hold_repeat (bool) – If True, the when_held handler will be repeatedly executed as long as the device remains active, every hold_time seconds.

wait_for_press(timeout=None)¶

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

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

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. Defaults to False.

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 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 will be passed as that parameter.

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

Line Sensor (TRCT5000)¶

class gpiozero.LineSensor(pin)[source]¶

Extends DigitalInputDevice 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) – The GPIO pin which the button is attached to. See Notes for valid pin numbers.
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 mean 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.

wait_for_line(timeout=None)¶

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

Parameters:	timeout (float) – 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) – 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.

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 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 will be passed as that parameter.

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

Motion Sensor (D-SUN PIR)¶

class gpiozero.MotionSensor(pin, queue_len=1, sample_rate=10, threshold=0.5, partial=False)[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) – The GPIO pin which the button is attached to. See Notes for valid pin numbers.
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 100.
threshold (float) – Defaults to 0.5. When the mean 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.

wait_for_motion(timeout=None)¶

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

Parameters:	timeout (float) – 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) – 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 device is currently active 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.

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 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 will be passed as that parameter.

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

Light Sensor (LDR)¶

class gpiozero.LightSensor(pin, queue_len=5, charge_time_limit=0.01, threshold=0.1, partial=False)[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) – The GPIO pin which the button is attached to. See Notes for valid pin numbers.
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 0.01µf 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 mean 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.

wait_for_dark(timeout=None)¶

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

Parameters:	timeout (float) – 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) – 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 device is currently active 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.

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 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 will be passed as that parameter.

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

Distance Sensor (HC-SR04)¶

class gpiozero.DistanceSensor(echo, trigger, queue_len=30, max_distance=1, threshold_distance=0.3, partial=False)[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 a 330Ω resistor from the ECHO pin of the sensor to a different GPIO pin.
Connect a 470Ω resistor from ground to the ECHO GPIO pin. This forms the required voltage divider.
Finally, connect the VCC pin of the sensor to a 5V pin on the Pi.

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

Parameters:

echo (int) – The GPIO pin which the ECHO pin is attached to. See Notes for valid pin numbers.
trigger (int) – The GPIO pin which the TRIG pin is attached to. See Notes for valid pin numbers.
queue_len (int) – The length of the queue used to store values read from the sensor. This defaults to 30.
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.

wait_for_in_range(timeout=None)¶

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

Parameters:	timeout (float) – 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) – 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.

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 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 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:

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, bounce_time=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:	bouncetime (float) – 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.

SmoothedInputDevice¶

class gpiozero.SmoothedInputDevice(pin=None, pull_up=False, threshold=0.5, queue_len=5, sample_wait=0.0, partial=False)[source]¶

Represents a generic input device which takes its value from the mean 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 mean 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:

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.

close()[source]¶

Shut down the device and release all associated resources. This method can be called on an already closed device without raising an exception.

This method 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()
...

is_active¶: Returns True if the device is currently active 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 mean 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)[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) – The GPIO pin (in Broadcom numbering) that the device is connected to. If this is `None` a `GPIODeviceError` will be raised. pull_up (bool) – If `True`, the pin will be pulled high with an internal resistor. If `False` (the default), the pin will be pulled low.

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

GPIODevice¶

class gpiozero.GPIODevice(pin)[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) – The GPIO pin (in BCM numbering) that the device is connected to. If this is `None`, `GPIOPinMissing` 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. This method can be called on an already closed device without raising an exception.

This method 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()
...

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.

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. See the Recipes page for more information.

LED¶

class gpiozero.LED(pin, active_high=True, initial_value=False)[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) – The GPIO pin which the LED is attached to. See Notes for valid pin numbers.
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) – 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.

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) – 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.

PWMLED¶

class gpiozero.PWMLED(pin, active_high=True, initial_value=0, frequency=100)[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) – The GPIO pin which the LED is attached to. See Notes for valid pin numbers.
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) – 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.

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) – 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()¶: 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))[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 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)

Parameters:

red (int) – The GPIO pin that controls the red component of the RGB LED.
green (int) – The GPIO pin that controls the green component of the RGB LED.
blue (int) – 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 (bool) – The initial color for the LED. Defaults to black (0, 0, 0).

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.
fade_out_time (float) – Number of seconds to spend fading out. Defaults to 0.
on_color (tuple) – The color to use when the LED is “on”. Defaults to white.
off_color (tuple) – The color to use when the LED is “off”. Defaults to black.
n (int) – 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).

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.

color¶

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).

is_lit¶: Returns True if the LED is currently active (not black) and False otherwise.

Buzzer¶

class gpiozero.Buzzer(pin, active_high=True, initial_value=False)[source]¶

Extends 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()

Parameters:

pin (int) – The GPIO pin which the buzzer is attached to. See Notes for valid pin numbers.
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) – 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.

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) – 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.

Motor¶

class gpiozero.Motor(forward, backward)[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) – The GPIO pin that the forward input of the motor driver chip is connected to. backward (int) – The GPIO pin that the backward input of the motor driver chip is connected to.

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).

stop()[source]¶: Stop the motor.

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:

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)[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.

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) – 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).

close()[source]¶

Shut down the device and release all associated resources. This method can be called on an already closed device without raising an exception.

This method 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()
...

off()[source]¶: Turns the device off.

on()[source]¶: Turns the device on.

PWMOutputDevice¶

class gpiozero.PWMOutputDevice(pin, active_high=True, initial_value=0, frequency=100)[source]¶

Generic output device configured for pulse-width modulation (PWM).

Parameters:

pin (int) – The GPIO pin which the device is attached to. See Notes for valid pin numbers.
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) – 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.

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) – 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).

close()[source]¶

Shut down the device and release all associated resources. This method can be called on an already closed device without raising an exception.

This method 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()
...

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) – 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()[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)[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) – The GPIO pin (in BCM numbering) that the device is connected to. If this is None a GPIOPinMissing 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) – 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.

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 True if the device is currently active and False otherwise. Setting this property changes the state of the device.

GPIODevice¶

class gpiozero.GPIODevice(pin)[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) – The GPIO pin (in BCM numbering) that the device is connected to. If this is `None`, `GPIOPinMissing` 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. This method can be called on an already closed device without raising an exception.

This method 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()
...

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.

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.

Hence the following constructors are all equiavlent:

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)¶

class gpiozero.MCP3001(**spi_args)[source]¶

The MCP3001 is a 10-bit analog to digital converter with 1 channel

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).

class gpiozero.MCP3002(channel=0, differential=False, **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), and the MCP3301 only has 1 channel.

differential¶

If True, the device is operated in pseudo-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 devices operating in differential mode).

class gpiozero.MCP3004(channel=0, differential=False, **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), and the MCP3301 only has 1 channel.

differential¶

If True, the device is operated in pseudo-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 devices operating in differential mode).

class gpiozero.MCP3008(channel=0, differential=False, **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), and the MCP3301 only has 1 channel.

differential¶

If True, the device is operated in pseudo-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 devices operating in differential mode).

class gpiozero.MCP3201(**spi_args)[source]¶

The MCP3201 is a 12-bit analog to digital converter with 1 channel

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).

class gpiozero.MCP3202(channel=0, differential=False, **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), and the MCP3301 only has 1 channel.

differential¶

If True, the device is operated in pseudo-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 devices operating in differential mode).

class gpiozero.MCP3204(channel=0, differential=False, **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), and the MCP3301 only has 1 channel.

differential¶

If True, the device is operated in pseudo-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 devices operating in differential mode).

class gpiozero.MCP3208(channel=0, differential=False, **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), and the MCP3301 only has 1 channel.

differential¶

If True, the device is operated in pseudo-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 devices operating in differential mode).

class gpiozero.MCP3301(**spi_args)[source]¶

The MCP3301 is a signed 13-bit analog to digital converter. Please note that the MCP3301 always operates in differential mode between its two channels and the 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).

class gpiozero.MCP3302(channel=0, differential=False, **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), and the MCP3301 only has 1 channel.

differential¶

If True, the device is operated in pseudo-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 devices operating in differential mode).

class gpiozero.MCP3304(channel=0, differential=False, **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), and the MCP3301 only has 1 channel.

differential¶

If True, the device is operated in pseudo-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 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:

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

AnalogInputDevice¶

class gpiozero.AnalogInputDevice(bits=None, **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.values

bits¶: The bit-resolution of the device/channel.

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 devices operating in differential mode).

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. This method can be called on an already closed device without raising an exception.

This method 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()
...

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 Input Devices and 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. See the Recipes page for more information.

LEDBoard¶

class gpiozero.LEDBoard(*pins, pwm=False, active_high=True, initial_value=False, **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 (int) – Specify the GPIO pins that the LEDs of the board are attached to. 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. This parameter can only be specified as a keyword parameter.
active_high (bool) – If True (the default), the on() method will set all the associates pins to HIGH. If False, the on() method will set all pins to LOW (the off() method always does the opposite).
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.
**named_pins – Sepcify GPIO pins that LEDs of the board are attached to, associated each LED with a property name. You can designate as many pins as necessary and any name provided it’s 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) – 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).

close()[source]¶

Shut down the device and release all associated resources. This method can be called on an already closed device without raising an exception.

This method 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()
...

off(*args)[source]¶: Turn all the output devices off.

on(*args)[source]¶: Turn all the output devices 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) – 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]¶: Toggle all the output devices. For each device, if it’s on, turn it off; if it’s off, turn it on.

leds¶: A flat iterator over all LEDs contained in this collection (and all sub-collections).

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.

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.

values¶: An infinite iterator of values read from value.

LEDBarGraph¶

class gpiozero.LEDBarGraph(*pins, initial_value=0)[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 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.values
pause()

Parameters:

*pins (int) – Specify the GPIO pins that the LEDs of the bar graph are attached to. You can designate as many pins as necessary.
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.
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.

off()¶: Turn all the output devices off.

on()¶: Turn all the output devices on.

toggle()¶: Toggle all the output devices. For each device, if it’s on, turn it off; if it’s off, turn it on.

leds¶: A flat iterator over all LEDs contained in this collection (and all sub-collections).

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.

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.

TrafficLights¶

class gpiozero.TrafficLights(red=None, amber=None, green=None, pwm=False)[source]¶

Extends LEDBoard for devices containing red, amber, and green LEDs.

The following example initializes a device connected to GPIO pins 2, 3, and 4, then lights the amber LED attached to GPIO 3:

from gpiozero import TrafficLights

traffic = TrafficLights(2, 3, 4)
traffic.amber.on()

Parameters:	red (int) – The GPIO pin that the red LED is attached to. amber (int) – The GPIO pin that the amber LED is attached to. green (int) – The GPIO pin that the green LED is attached to. pwm (bool) – If `True`, construct `PWMLED` instances to represent each LED. If `False` (the default), construct regular `LED` instances.

blink(on_time=1, off_time=1, fade_in_time=0, fade_out_time=0, n=None, background=True)¶

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) – 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).

close()¶

Shut down the device and release all associated resources. This method can be called on an already closed device without raising an exception.

This method 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()
...

off(*args)¶: Turn all the output devices off.

on(*args)¶: Turn all the output devices 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) – 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)¶: Toggle all the output devices. For each device, if it’s on, turn it off; if it’s off, turn it on.

leds¶: A flat iterator over all LEDs contained in this collection (and all sub-collections).

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.

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.

values¶: An infinite iterator of values read from value.

PiLITEr¶

class gpiozero.PiLiter(pwm=False)[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. This parameter can only be specified as a keyword parameter.

blink(on_time=1, off_time=1, fade_in_time=0, fade_out_time=0, n=None, background=True)¶

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) – 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).

close()¶

Shut down the device and release all associated resources. This method can be called on an already closed device without raising an exception.

This method 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()
...

off(*args)¶: Turn all the output devices off.

on(*args)¶: Turn all the output devices 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) – 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)¶: Toggle all the output devices. For each device, if it’s on, turn it off; if it’s off, turn it on.

leds¶: A flat iterator over all LEDs contained in this collection (and all sub-collections).

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.

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.

values¶: An infinite iterator of values read from value.

PiLITEr Bar Graph¶

class gpiozero.PiLiterBarGraph(initial_value=0)[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:	initial_value (bool) – The initial value of the graph given as a float between -1 and +1. Defaults to 0.0.

off()¶: Turn all the output devices off.

on()¶: Turn all the output devices on.

toggle()¶: Toggle all the output devices. For each device, if it’s on, turn it off; if it’s off, turn it on.

leds¶: A flat iterator over all LEDs contained in this collection (and all sub-collections).

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.

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.

PI-TRAFFIC¶

class gpiozero.PiTraffic[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.

blink(on_time=1, off_time=1, fade_in_time=0, fade_out_time=0, n=None, background=True)¶

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) – 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).

close()¶

Shut down the device and release all associated resources. This method can be called on an already closed device without raising an exception.

This method 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()
...

off(*args)¶: Turn all the output devices off.

on(*args)¶: Turn all the output devices 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) – 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)¶: Toggle all the output devices. For each device, if it’s on, turn it off; if it’s off, turn it on.

leds¶: A flat iterator over all LEDs contained in this collection (and all sub-collections).

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.

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.

values¶: An infinite iterator of values read from value.

TrafficLightsBuzzer¶

class gpiozero.TrafficLightsBuzzer(lights, buzzer, button)[source]¶

Extends CompositeDevice 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.

off()¶: Turn all the output devices off.

on()¶: Turn all the output devices on.

toggle()¶: Toggle all the output devices. For each device, if it’s on, turn it off; if it’s off, turn it on.

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.

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.

values¶: An infinite iterator of values read from value.

Fish Dish¶

class gpiozero.FishDish(pwm=False)[source]¶

Extends TrafficLightsBuzzer 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.

off()¶: Turn all the output devices off.

on()¶: Turn all the output devices on.

toggle()¶: Toggle all the output devices. For each device, if it’s on, turn it off; if it’s off, turn it on.

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.

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.

values¶: An infinite iterator of values read from value.

Traffic HAT¶

class gpiozero.TrafficHat(pwm=False)[source]¶

Extends TrafficLightsBuzzer for the Ryanteck Traffic HAT: 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.

off()¶: Turn all the output devices off.

on()¶: Turn all the output devices on.

toggle()¶: Toggle all the output devices. For each device, if it’s on, turn it off; if it’s off, turn it on.

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.

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.

values¶: An infinite iterator of values read from value.

Robot¶

class gpiozero.Robot(left=None, right=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 turn the robot left:

from gpiozero import Robot

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

Parameters:	left (tuple) – A tuple of two GPIO pins representing the forward and backward inputs of the left motor’s controller. right (tuple) – A tuple of two GPIO pins representing the forward and backward inputs of the right motor’s controller.

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.

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.

values¶: An infinite iterator of values read from value.

Ryanteck MCB Robot¶

class gpiozero.RyanteckRobot[source]¶

Extends Robot for the Ryanteck MCB robot.

The Ryanteck MCB pins are fixed and therefore there’s no need to specify them when constructing this class. The following example turns the robot left:

from gpiozero import RyanteckRobot

robot = RyanteckRobot()
robot.left()

backward(speed=1)¶

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)¶

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)¶

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()¶: 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)¶

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()¶: Stop the robot.

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.

values¶: An infinite iterator of values read from value.

CamJam #3 Kit Robot¶

class gpiozero.CamJamKitRobot[source]¶

Extends Robot for the CamJam #3 EduKit robot controller.

The CamJam robot controller pins are fixed and therefore there’s no need to specify them when constructing this class. The following example turns the robot left:

from gpiozero import CamJamKitRobot

robot = CamJamKitRobot()
robot.left()

backward(speed=1)¶

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)¶

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)¶

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()¶: 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)¶

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()¶: Stop the robot.

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.

values¶: An infinite iterator of values read from value.

Energenie¶

class gpiozero.Energenie(socket=None, initial_value=False)[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) – The initial state of the socket. As Energenie sockets provide no means of reading their state, you must provide an initial state for the socket, which will be set upon construction. This defaults to `False` which will switch the socket off.

close()[source]¶

Shut down the device and release all associated resources. This method can be called on an already closed device without raising an exception.

This method 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()
...

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.

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.

values¶: An infinite iterator of values read from value.

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(*args, **kwargs)[source]¶

Extends CompositeOutputDevice. Abstract base class for LEDBoard and LEDBarGraph.

leds¶: A flat iterator over all LEDs contained in this collection (and all sub-collections).

CompositeOutputDevice¶

class gpiozero.CompositeOutputDevice(*args, _order=None, **kwargs)[source]¶

Extends CompositeDevice with on(), off(), and toggle() methods for controlling subordinate output devices. Also extends value to be writeable.

Parameters:	_order (list) – 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.

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, **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 via the all attribute, while keyword arguments are added to the device as named (read-only) attributes.

Parameters:	_order (list) – 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.

close()[source]¶

Shut down the device and release all associated resources. This method can be called on an already closed device without raising an exception.

This method 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()
...

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.

Warning

These devices are experimental and their API is not yet considered stable. We welcome any comments from testers, especially regarding new “internal devices” that you’d find useful!

TimeOfDay¶

class gpiozero.TimeOfDay(start_time, end_time, utc=True)[source]¶

Extends InternalDevice 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 7 and 8 AM:

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

lamp = Energenie(0)
morning = TimeOfDay(time(7), time(8))
morning.when_activated = lamp.on
morning.when_deactivated = lamp.off
pause()

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.

PingServer¶

class gpiozero.PingServer(host)[source]¶

Extends InternalDevice to provide a device which is active when a host on the network can be pinged.

The following example lights an LED while a server is reachable (note the use of source_delay to ensure the server is not flooded with pings):

from gpiozero import PingServer, LED
from signal import pause

server = PingServer('my-server')
led = LED(4)
led.source_delay = 1
led.source = server.values
pause()

Parameters:	host (str) – The hostname or IP address to attempt to ping.

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:

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

InternalDevice¶

class gpiozero.InternalDevice[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.

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:

Device¶

class gpiozero.Device[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 thhe is_active property, the value property, and the close() method).

close()¶

Shut down the device and release all associated resources. This method can be called on an already closed device without raising an exception.

This method 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, 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]¶: Given the constructor arguments, returns an immutable key representing the instance. The default simply assumes all positional arguments are immutable.

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) – 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) – 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 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 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.

Source Tools¶

GPIO Zero includes several utility routines which are intended to be used with the source and 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, conjunction

Given that source and values deal with infinite iterators, another excellent source of utilities is the itertools module in the standard library.

Warning

While the devices API is now considered stable and won’t change in backwards incompatible ways, the tools API is not yet considered stable. It is potentially subject to change in future versions. We welcome any comments from testers!

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.values, -1, 1)
led.source = absoluted(motor.values)
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.values, 0.5, 1.0)
pause()

gpiozero.tools.inverted(values)[source]¶

Returns the inversion of the supplied values (1 becomes 0, 0 becomes 1, 0.1 becomes 0.9, etc.). 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.values)
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.values)
pause()

gpiozero.tools.post_delayed(values, delay)[source]¶: Waits for delay seconds after returning each item from values.

gpiozero.tools.pre_delayed(values, delay)[source]¶: Waits for delay seconds before returning each item from values.

gpiozero.tools.quantized(values, steps, output_min=0, output_max=1)[source]¶

Returns values quantized to steps increments. All items in values are assumed to be between output_min and output_max (use scaled() to ensure this if necessary).

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.values, 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].values, 5)
    leds[i].source_delay = 0.01
leds[4].source = btn.values
pause()

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.values, -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.values, btn2.values)
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.values, btn2.values)
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.values, pot2.values, pot3.values)
pause()

Artifical sources¶

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, inverted
from signal import pause

red = PWMLED(2)
blue = PWMLED(3)
red.source_delay = 0.01
blue.source_delay = 0.01
red.source = scaled(cos_values(100), 0, 1, -1, 1)
blue.source = inverted(red.values)
pause()

If you require a different range than -1 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, inverted
from signal import pause

red = PWMLED(2)
blue = PWMLED(3)
red.source_delay = 0.01
blue.source_delay = 0.01
red.source = scaled(sin_values(100), 0, 1, -1, 1)
blue.source = inverted(red.values)
pause()

If you require a different range than -1 to +1, see scaled().

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 GPIO pin number. However, what the library actually expects is a Pin implementation. If it finds a simple integer number instead, it uses one of the following classes to provide the Pin implementation (classes are listed in favoured order):

gpiozero.pins.rpigpio.RPiGPIOPin
gpiozero.pins.rpio.RPIOPin
gpiozero.pins.pigpiod.PiGPIOPin
gpiozero.pins.native.NativePin

You can change the default pin implementation by over-writing the DefaultPin global in the devices module like so:

from gpiozero.pins.native import NativePin
import gpiozero.devices
# Force the default pin implementation to be NativePin
gpiozero.devices.DefaultPin = NativePin

from gpiozero import LED

# This will now use NativePin instead of RPiGPIOPin
led = LED(16)

Alternatively, instead of passing an integer to the device constructor, you can pass a Pin object itself:

from gpiozero.pins.native import NativePin
from gpiozero import LED

led = LED(NativePin(16))

This is particularly useful with implementations that can take extra parameters such as PiGPIOPin which can address pins on remote machines:

from gpiozero.pins.pigpiod import PiGPIOPin
from gpiozero import LED

led = LED(PiGPIOPin(16, host='my_other_pi'))

In future, this separation of pins and devices should also permit the library to utilize pins that are part of IO extender chips. For example:

from gpiozero import IOExtender, LED

ext = IOExtender()
led = LED(ext.pins[0])
led.on()

Warning

While the devices API is now considered stable and won’t change in backwards incompatible ways, the pins API is not yet considered stable. It is potentially subject to change in future versions. We welcome any comments from testers!

Warning

The astute and mischievous reader may note that it is possible to mix pin implementations, e.g. using RPiGPIOPin for one pin, and NativePin 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.

RPiGPIOPin¶

class gpiozero.pins.rpigpio.RPiGPIOPin[source]¶

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 RPiGPIOPin
from gpiozero import LED

led = LED(RPiGPIOPin(12))

RPIOPin¶

class gpiozero.pins.rpio.RPIOPin[source]¶

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 RPIOPin
from gpiozero import LED

led = LED(RPIOPin(12))

PiGPIOPin¶

class gpiozero.pins.pigpiod.PiGPIOPin[source]¶

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 pigpiod pins manually like so:

from gpiozero.pins.pigpiod import PiGPIOPin
from gpiozero import LED

led = LED(PiGPIOPin(12))

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.pigpiod import PiGPIOPin
from gpiozero import LED
from signal import pause

led = LED(PiGPIOPin(12, host='192.168.0.2'))

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.

NativePin¶

class gpiozero.pins.native.NativePin[source]¶

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. This implementation is also experimental; we make no guarantees it will not eat your Pi for breakfast!

You can construct native pin instances manually like so:

from gpiozero.pins.native import NativePin
from gpiozero import LED

led = LED(NativePin(12))

Abstract Pin¶

class gpiozero.Pin[source]¶

Abstract base class representing a GPIO pin or a pin from an IO extender.

Descendents should override property getters and setters to accurately represent the capabilities of pins. The following functions must be overridden:

_get_function()
_set_function()
_get_state()

The following functions may be overridden if applicable:

close()
_set_state()
_get_frequency()
_set_frequency()
_get_pull()
_set_pull()
_get_bounce()
_set_bounce()
_get_edges()
_set_edges()
_get_when_changed()
_set_when_changed()
output_with_state()
input_with_pull()

Warning

Descendents must ensure that pin instances representing the same physical hardware are identical, right down to object identity. The framework relies on this to correctly clean up resources at interpreter shutdown.

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.

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”.

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).

If PWM is currently active (when frequency is not None), this represents the PWM duty cycle as a value between 0.0 and 1.0.

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 take no parameters.

If the pin does not support edge detection, attempts to set this property will raise PinEdgeDetectUnsupported.

Utilities¶

The pins module also contains a database of information about the various revisions of Raspberry Pi. 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:

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.

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.

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.

Note

This does not include the micro-USB port used to power the Pi. On the Compute Module this is listed as 0 as the compute module itself doesn’t have any physical USB headers, despite providing one on the I/O development board and having the pins for one on the module itself.

ethernet¶: An integer indicating how many Ethernet ports are physically present on this revision of the Pi.

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 dictionaries which map physical pin numbers to PinInfo tuples. For example, to obtain information about pin 12 on header P1 you would query headers['P1'][12].

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.

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:

from gpiozero import *

led = PWMLED(17)
try:
    led.value = 2
except ValueError:
    print('Bad value specified')

Errors¶

exception gpiozero.GPIOZeroError[source]¶: Base class for all exceptions in GPIO Zero

exception gpiozero.DeviceClosed[source]¶: Error raised when an operation is attempted on a closed device

exception gpiozero.BadEventHandler[source]¶: Error raised when an event handler with an incompatible prototype is specified

exception gpiozero.BadQueueLen[source]¶: Error raised when non-positive queue length is specified

exception gpiozero.BadWaitTime[source]¶: Error raised when an invalid wait time is specified

exception gpiozero.CompositeDeviceError[source]¶: Base class for errors specific to the CompositeDevice hierarchy

exception gpiozero.CompositeDeviceBadName[source]¶: Error raised when a composite device is constructed with a reserved name

exception gpiozero.EnergenieSocketMissing[source]¶: Error raised when socket number is not specified

exception gpiozero.EnergenieBadSocket[source]¶: Error raised when an invalid socket number is passed to Energenie

exception gpiozero.SPIError[source]¶: Base class for errors related to the SPI implementation

exception gpiozero.SPIBadArgs[source]¶: Error raised when invalid arguments are given while constructing SPIDevice

exception gpiozero.GPIODeviceError[source]¶: Base class for errors specific to the GPIODevice hierarchy

exception gpiozero.GPIODeviceClosed[source]¶: Deprecated descendent of DeviceClosed

exception gpiozero.GPIOPinInUse[source]¶: Error raised when attempting to use a pin already in use by another device

exception gpiozero.GPIOPinMissing[source]¶: Error raised when a pin number is not specified

exception gpiozero.InputDeviceError[source]¶: Base class for errors specific to the InputDevice hierarchy

exception gpiozero.OutputDeviceError[source]¶: Base class for errors specified to the OutputDevice hierarchy

exception gpiozero.OutputDeviceBadValue[source]¶: Error raised when value is set to an invalid value

exception gpiozero.PinError[source]¶: Base class for errors related to pin implementations

exception gpiozero.PinInvalidFunction[source]¶: Error raised when attempting to change the function of a pin to an invalid value

exception gpiozero.PinInvalidState[source]¶: Error raised when attempting to assign an invalid state to a pin

exception gpiozero.PinInvalidPull[source]¶: Error raised when attempting to assign an invalid pull-up to a pin

exception gpiozero.PinInvalidEdges[source]¶: Error raised when attempting to assign an invalid edge detection to a pin

exception gpiozero.PinSetInput[source]¶: Error raised when attempting to set a read-only pin

exception gpiozero.PinFixedPull[source]¶: Error raised when attempting to set the pull of a pin with fixed pull-up

exception gpiozero.PinEdgeDetectUnsupported[source]¶: Error raised when attempting to use edge detection on unsupported pins

exception gpiozero.PinPWMError[source]¶: Base class for errors related to PWM implementations

exception gpiozero.PinPWMUnsupported[source]¶: Error raised when attempting to activate PWM on unsupported pins

exception gpiozero.PinPWMFixedValue[source]¶: Error raised when attempting to initialize PWM on an input pin

exception gpiozero.PinMultiplePins[source]¶: Error raised when multiple pins support the requested function

exception gpiozero.PinNoPins[source]¶: Error raised when no pins support the requested function

exception gpiozero.PinUnknownPi[source]¶: Error raised when gpiozero doesn’t recognize a revision of the Pi

Warnings¶

exception gpiozero.GPIOZeroWarning[source]¶: Base class for all warnings in GPIO Zero

exception gpiozero.SPIWarning[source]¶: Base class for warnings related to the SPI implementation

exception gpiozero.SPISoftwareFallback[source]¶: Warning raised when falling back to the software implementation

Changelog¶

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¶

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.