mirror of
https://github.com/KevinMidboe/python-gpiozero.git
synced 2025-10-29 17:50:37 +00:00
705 lines
14 KiB
ReStructuredText
705 lines
14 KiB
ReStructuredText
=======
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Recipes
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=======
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.. currentmodule:: gpiozero
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The following recipes demonstrate some of the capabilities of the gpiozero
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library. Please note that all recipes are written assuming Python 3. Recipes
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*may* work under Python 2, but no guarantees!
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Pin Numbering
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=============
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This library uses Broadcom (BCM) pin numbering for the GPIO pins, as opposed
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to physical (BOARD) numbering. Unlike in the `RPi.GPIO`_ library, this is not
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configurable.
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.. _RPi.GPIO: https://pypi.python.org/pypi/RPi.GPIO
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Any pin marked ``GPIO`` in the diagram below can be used for generic
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components:
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.. image:: images/pin_layout.*
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LED
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===
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.. image:: images/led.*
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Turn an :class:`LED` on and off repeatedly::
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from gpiozero import LED
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from time import sleep
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red = LED(17)
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while True:
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red.on()
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sleep(1)
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red.off()
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sleep(1)
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Alternatively::
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from gpiozero import LED
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from signal import pause
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red = LED(17)
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red.blink()
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pause()
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.. note::
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Reaching the end of a Python script will terminate the process and GPIOs
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may be reset. Keep your script alive with :func:`signal.pause`. See
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:ref:`keep-your-script-running` for more information.
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Button
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======
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.. image:: images/button.*
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Check if a :class:`Button` is pressed::
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from gpiozero import Button
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button = Button(2)
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while True:
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if button.is_pressed:
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print("Button is pressed")
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else:
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print("Button is not pressed")
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Wait for a button to be pressed before continuing::
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from gpiozero import Button
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button = Button(2)
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button.wait_for_press()
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print("Button was pressed")
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Run a function every time the button is pressed::
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from gpiozero import Button
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from signal import pause
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def say_hello():
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print("Hello!")
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button = Button(2)
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button.when_pressed = say_hello
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pause()
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Button controlled LED
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=====================
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.. image:: images/led_button_bb.*
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Turn on an :class:`LED` when a :class:`Button` is pressed::
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from gpiozero import LED, Button
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from signal import pause
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led = LED(17)
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button = Button(2)
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button.when_pressed = led.on
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button.when_released = led.off
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pause()
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Alternatively::
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from gpiozero import LED, Button
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from signal import pause
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led = LED(17)
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button = Button(2)
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led.source = button.values
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pause()
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Traffic Lights
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==============
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.. image:: images/traffic_lights_bb.*
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A full traffic lights system.
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Using a :class:`TrafficLights` kit like Pi-Stop::
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from gpiozero import TrafficLights
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from time import sleep
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lights = TrafficLights(2, 3, 4)
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lights.green.on()
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while True:
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sleep(10)
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lights.green.off()
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lights.amber.on()
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sleep(1)
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lights.amber.off()
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lights.red.on()
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sleep(10)
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lights.amber.on()
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sleep(1)
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lights.green.on()
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lights.amber.off()
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lights.red.off()
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Alternatively::
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from gpiozero import TrafficLights
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from time import sleep
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from signal import pause
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lights = TrafficLights(2, 3, 4)
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def traffic_light_sequence():
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while True:
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yield (0, 0, 1) # green
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sleep(10)
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yield (0, 1, 0) # amber
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sleep(1)
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yield (1, 0, 0) # red
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sleep(10)
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yield (1, 1, 0) # red+amber
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sleep(1)
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lights.source = traffic_light_sequence()
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pause()
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Using :class:`LED` components::
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from gpiozero import LED
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from time import sleep
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red = LED(2)
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amber = LED(3)
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green = LED(4)
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green.on()
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amber.off()
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red.off()
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while True:
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sleep(10)
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green.off()
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amber.on()
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sleep(1)
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amber.off()
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red.on()
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sleep(10)
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amber.on()
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sleep(1)
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green.on()
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amber.off()
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red.off()
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Push button stop motion
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=======================
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Capture a picture with the camera module every time a button is pressed::
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from gpiozero import Button
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from picamera import PiCamera
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button = Button(2)
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with PiCamera() as camera:
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camera.start_preview()
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frame = 1
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while True:
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button.wait_for_press()
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camera.capture('/home/pi/frame%03d.jpg' % frame)
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frame += 1
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See `Push Button Stop Motion`_ for a full resource.
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Reaction Game
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=============
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.. image:: images/reaction_game_bb.*
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When you see the light come on, the first person to press their button wins!
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::
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from gpiozero import Button, LED
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from time import sleep
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import random
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led = LED(17)
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player_1 = Button(2)
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player_2 = Button(3)
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time = random.uniform(5, 10)
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sleep(time)
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led.on()
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while True:
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if player_1.is_pressed:
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print("Player 1 wins!")
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break
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if player_2.is_pressed:
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print("Player 2 wins!")
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break
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led.off()
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See `Quick Reaction Game`_ for a full resource.
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GPIO Music Box
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==============
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Each button plays a different sound!
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::
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from gpiozero import Button
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import pygame.mixer
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from pygame.mixer import Sound
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from signal import pause
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pygame.mixer.init()
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sound_pins = {
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2: Sound("samples/drum_tom_mid_hard.wav"),
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3: Sound("samples/drum_cymbal_open.wav"),
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}
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buttons = [Button(pin) for pin in sound_pins]
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for button in buttons:
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sound = sound_pins[button.pin.number]
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button.when_pressed = sound.play
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pause()
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See `GPIO Music Box`_ for a full resource.
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All on when pressed
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===================
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While the button is pressed down, the buzzer and all the lights come on.
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:class:`FishDish`::
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from gpiozero import FishDish
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from signal import pause
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fish = FishDish()
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fish.button.when_pressed = fish.on
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fish.button.when_released = fish.off
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pause()
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Ryanteck :class:`TrafficHat`::
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from gpiozero import TrafficHat
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from signal import pause
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th = TrafficHat()
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th.button.when_pressed = th.on
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th.button.when_released = th.off
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pause()
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Using :class:`LED`, :class:`Buzzer`, and :class:`Button` components::
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from gpiozero import LED, Buzzer, Button
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from signal import pause
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button = Button(2)
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buzzer = Buzzer(3)
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red = LED(4)
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amber = LED(5)
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green = LED(6)
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things = [red, amber, green, buzzer]
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def things_on():
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for thing in things:
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thing.on()
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def things_off():
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for thing in things:
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thing.off()
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button.when_pressed = things_on
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button.when_released = things_off
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pause()
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RGB LED
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=======
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.. image:: images/rgb_led_bb.*
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Making colours with an :class:`RGBLED`::
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from gpiozero import RGBLED
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from time import sleep
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led = RGBLED(red=9, green=10, blue=11)
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led.red = 1 # full red
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sleep(1)
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led.red = 0.5 # half red
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sleep(1)
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led.color = (0, 1, 0) # full green
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sleep(1)
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led.color = (1, 0, 1) # magenta
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sleep(1)
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led.color = (1, 1, 0) # yellow
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sleep(1)
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led.color = (0, 1, 1) # cyan
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sleep(1)
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led.color = (1, 1, 1) # white
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sleep(1)
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led.color = (0, 0, 0) # off
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sleep(1)
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# slowly increase intensity of blue
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for n in range(100):
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led.blue = n/100
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sleep(0.1)
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Motion sensor
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=============
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.. image:: images/motion_sensor_bb.*
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Light an :class:`LED` when a :class:`MotionSensor` detects motion::
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from gpiozero import MotionSensor, LED
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from signal import pause
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pir = MotionSensor(4)
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led = LED(16)
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pir.when_motion = led.on
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pir.when_no_motion = led.off
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pause()
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Light sensor
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============
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.. image:: images/light_sensor_bb.*
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Have a :class:`LightSensor` detect light and dark::
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from gpiozero import LightSensor
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sensor = LightSensor(18)
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while True:
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sensor.wait_for_light()
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print("It's light! :)")
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sensor.wait_for_dark()
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print("It's dark :(")
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Run a function when the light changes::
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from gpiozero import LightSensor, LED
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from signal import pause
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sensor = LightSensor(18)
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led = LED(16)
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sensor.when_dark = led.on
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sensor.when_light = led.off
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pause()
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Or make a :class:`PWMLED` change brightness according to the detected light
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level::
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from gpiozero import LightSensor, LED
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from signal import pause
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sensor = LightSensor(18)
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led = PWMLED(16)
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led.source = sensor.values
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pause()
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Distance sensor
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===============
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.. IMAGE TBD
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Have a :class:`DistanceSensor` detect the distance to the nearest object::
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from gpiozero import DistanceSensor
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from time import sleep
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sensor = DistanceSensor(23, 24)
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while True:
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print('Distance to nearest object is', sensor.distance, 'm')
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sleep(1)
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Run a function when something gets near the sensor::
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from gpiozero import DistanceSensor, LED
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from signal import pause
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sensor = DistanceSensor(23, 24, max_distance=1, threshold_distance=0.2)
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led = LED(16)
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sensor.when_in_range = led.on
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sensor.when_out_of_range = led.off
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pause()
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Motors
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======
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.. image:: images/motor_bb.*
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Spin a :class:`Motor` around forwards and backwards::
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from gpiozero import Motor
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from time import sleep
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motor = Motor(forward=4, back=14)
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while True:
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motor.forward()
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sleep(5)
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motor.backward()
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sleep(5)
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Robot
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=====
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.. IMAGE TBD
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Make a :class:`Robot` drive around in (roughly) a square::
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from gpiozero import Robot
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from time import sleep
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robot = Robot(left=(4, 14), right=(17, 18))
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for i in range(4):
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robot.forward()
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sleep(10)
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robot.right()
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sleep(1)
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Make a robot with a distance sensor that runs away when things get within
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20cm of it::
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from gpiozero import Robot, DistanceSensor
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from signal import pause
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sensor = DistanceSensor(23, 24, max_distance=1, threshold_distance=0.2)
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robot = Robot(left=(4, 14), right=(17, 18))
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sensor.when_in_range = robot.backward
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sensor.when_out_of_range = robot.stop
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pause()
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Button controlled robot
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=======================
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Use four GPIO buttons as forward/back/left/right controls for a robot::
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from gpiozero import RyanteckRobot, Button
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from signal import pause
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robot = RyanteckRobot()
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left = Button(26)
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right = Button(16)
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fw = Button(21)
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bw = Button(20)
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fw.when_pressed = robot.forward
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fw.when_released = robot.stop
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left.when_pressed = robot.left
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left.when_released = robot.stop
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right.when_pressed = robot.right
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right.when_released = robot.stop
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bw.when_pressed = robot.backward
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bw.when_released = robot.stop
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pause()
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Keyboard controlled robot
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=========================
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.. XXX Rewrite this using curses (to avoid evdev dep, which isn't packaged
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on Rapsbian)
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Use up/down/left/right keys to control a robot::
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from gpiozero import RyanteckRobot
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from evdev import InputDevice, list_devices, ecodes
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robot = RyanteckRobot()
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devices = [InputDevice(device) for device in list_devices()]
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keyboard = devices[0] # this may vary
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keypress_actions = {
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ecodes.KEY_UP: robot.forward,
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ecodes.KEY_DOWN: robot.backward,
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ecodes.KEY_LEFT: robot.left,
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ecodes.KEY_RIGHT: robot.right,
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}
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for event in keyboard.read_loop():
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if event.type == ecodes.EV_KEY:
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if event.value == 1: # key down
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keypress_actions[event.code]()
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if event.value == 0: # key up
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robot.stop()
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Motion sensor robot
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===================
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Make a robot drive forward when it detects motion::
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from gpiozero import Robot, MotionSensor
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from signal import pause
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robot = Robot(left=(4, 14), right=(17, 18))
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pir = MotionSensor(5)
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pir.when_motion = robot.forward
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pir.when_no_motion = robot.stop
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pause()
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Alternatively::
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from gpiozero import Robot, MotionSensor
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from signal import pause
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robot = Robot(left=(4, 14), right=(17, 18))
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pir = MotionSensor(5)
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robot.source = zip(pir.values, pir.values)
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pause()
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Potentiometer
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=============
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.. image:: images/potentiometer_bb.*
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Continually print the value of a potentiometer (values between 0 and 1)
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connected to a :class:`MCP3008` analog to digital converter::
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from gpiozero import MCP3008
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while True:
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with MCP3008(channel=0) as pot:
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print(pot.value)
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Measure temperature with an ADC
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===============================
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.. IMAGE TBD
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Wire a TMP36 temperature sensor to the first channel of an :class:`MCP3008`
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analog to digital converter::
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from gpiozero import MCP3008
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from time import sleep
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def convert_temp(gen):
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for value in gen:
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yield (value * 3.3 - 0.5) * 100
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adc = MCP3008(channel=0)
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for temp in convert_temp(adc.values):
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print('The temperature is', temp, 'C')
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sleep(1)
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Full color LED controlled by 3 potentiometers
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=============================================
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Wire up three potentiometers (for red, green and blue) and use each of their
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values to make up the colour of the LED::
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from gpiozero import RGBLED, MCP3008
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led = RGBLED(red=2, green=3, blue=4)
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red_pot = MCP3008(channel=0)
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green_pot = MCP3008(channel=1)
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blue_pot = MCP3008(channel=2)
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while True:
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led.red = red_pot.value
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led.green = green_pot.value
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led.blue = blue_pot.value
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Alternatively, the following example is identical, but uses the
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:attr:`~SourceMixin.source` property rather than a :keyword:`while` loop::
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from gpiozero import RGBLED, MCP3008
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from signal import pause
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led = RGBLED(2, 3, 4)
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red_pot = MCP3008(0)
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green_pot = MCP3008(1)
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blue_pot = MCP3008(2)
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led.source = zip(red_pot.values, green_pot.values, blue_pot.values)
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pause()
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Please note the example above requires Python 3. In Python 2, :func:`zip`
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doesn't support lazy evaluation so the script will simply hang.
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.. _Push Button Stop Motion: https://www.raspberrypi.org/learning/quick-reaction-game/
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.. _Quick Reaction Game: https://www.raspberrypi.org/learning/quick-reaction-game/
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.. _GPIO Music Box: https://www.raspberrypi.org/learning/gpio-music-box/
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