Physical computing with Python and Raspberry Pi - PyCon Russia

An introduction to the Raspberry Pi, and the Foundation's charitable work in education, and to getting started with physical computing using Python and GPIO Zero on the Raspberry Pi.

This was the closing talk at PyCon Russia 2016.

Transcript

1. Physical Computing with Python
   Ben Nuttall
   Raspberry Pi Foundation
   UK Charity 1129409
   

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2. Ben Nuttall
   ●
   Raspberry Pi Community Manager
   – Programmes & outreach
   – Software & project development
   – Learning resources & teacher training
   ●
   Hobbyist turned employee
   ●
   Based in Cambridge, UK
   ●
   @ben_nuttall on Twitter
   

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3. Raspberry Pi
   

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4. Raspberry Pi Foundation
   ●
   Educational charity founded
   in 2006
   ●
   Owns trading subsidiary
   Raspberry Pi Trading Ltd
   ●
   Trading profits fund
   educational programmes
   

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5. A Computer (1981)
   

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6. A Computer (2010)
   

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7. Prototypes
   

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8. Raspberry Pi (2012)
   Raspberry Pi Model B
   700MHz single core 32-bit CPU
   VideoCoreIV 3D GPU
   256MB RAM
   $35
   

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9. Raspberry Pi Community
   

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10. Raspberry Jam
    

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11. Raspberry Jam
    raspberrypi.org/jam
    

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12. Made in the UK
    ●
    Since 2013, Raspberry Pi has
    been manufactured by Sony
    in Wales
    ●
    20k units per day at peak
    

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13. Raspberry Pi Compute Module
    Prototyping development board
    Build your product around the
    Raspberry Pi
    

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14. Raspberry Pi Zero (2015)
    1GHz single core 32-bit CPU
    VideoCoreIV 3D GPU
    512MB RAM
    $5
    

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15. Raspberry Pi 3 Model B (2016)
    1.2GHz quad core 64-bit CPU
    VideoCoreIV 3D GPU
    1GB RAM
    $35
    

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16. Over 9 Million Raspberry Pis sold
    ●
    Minor revisions
    ●
    Model A
    ●
    Model B+
    ●
    Model A+
    ●
    Raspberry Pi 2 Model B
    ●
    Raspberry Pi Zero
    ●
    Raspberry Pi 3 Model B
    

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17. Raspberry Pi Foundation Mission
    “Putting the power of digital making into the hands of people all
    over the world”
    

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18. Raspberry Pi computers
    ●
    We produce low-cost high-
    power computers
    ●
    They keep getting better
    and/or cheaper :)
    ●
    Used in
    – education
    – hobby projects
    – industry
    

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19. Raspberry Pi in Schools
    

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20. Education
    ●
    We train teachers in
    computing
    ●
    We create free resources for
    use at home and school
    ●
    We run programmes to
    engage young people in
    digital making
    ●
    We support a network of Code
    Clubs in Primary Schools
    

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21. Raspbian
    

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22. Raspbian
    ●
    Launch programming
    applications
    ●
    Web browser
    ●
    Preferences and settings
    ●
    Shutdown & reboot
    ●
    Look – it's a real computer!
    

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23. Physical computing
    ●
    Flashy lights
    ●
    Motors & robots
    ●
    Photo & video
    ●
    Sensors
    ●
    Internet of Things
    ●
    Engaging and empowering
    

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24. GPIO Pins – General Purpose Input/Output
    

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25. GPIO components
    

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26. Add-on boards / HATs
    

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27. Python - RPi.GPIO
    import RPi.GPIO as GPIO
    from time import sleep
    GPIO.setmode(GPIO.BCM)
    GPIO.setwarnings(False)
    GPIO.setup(17, GPIO.OUT)
    while True:
    GPIO.output(17, GPIO.HIGH)
    sleep(1)
    GPIO.output(17, GPIO.LOW)
    sleep(1)
    

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28. GPIO in Scratch
    ●
    GPIO Server
    ●
    Use broadcast blocks
    ●
    Drag & drop programming
    – except when you have to
    write code in those broadcast
    blocks and get the syntax
    right as there's no error
    reporting...
    

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29. Something more approachable?
    ●
    Teachers saying Python is too hard to teach with
    – Particularly RPi.GPIO and PyGame
    ●
    Teachers staying in Scratch too long
    – Need help moving to Python
    – GPIO in Scratch is difficult
    ●
    Problems with RPi.GPIO
    – Too much boilerplate code required for even simple examples
    – Lots of copy/paste for complex components
    – Not Pythonic
    

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30. Python - GPIO Zero
    from gpiozero import LED
    from time import sleep
    led = LED(17)
    while True:
    led.on()
    sleep(1)
    led.off()
    sleep(1)
    

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31. Python - GPIO Zero
    from gpiozero import LED
    led = LED(17)
    led.blink()
    

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32. LED
    from gpiozero import LED
    led = LED(17)
    led.on() # on
    led.off() # off
    led.toggle() # on­>off or off­>on
    led.blink() # flash on/off continuously
    

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33. Buzzer
    from gpiozero import Buzzer
    buzzer = Buzzer(18)
    buzzer.on() # on
    buzzer.off() # off
    buzzer.toggle() # on­>off or off­>on
    buzzer.beep() # beep on/off continuously
    

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34. GitHub
    

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35. Button polling (pull-up) – RPi.GPIO
    GPIO.setup(4, GPIO.IN, GPIO.PUD_UP)
    while True:
    if not GPIO.input(4):
    print(“Pressed”)
    

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36. Button polling (pull-down) – RPi.GPIO
    GPIO.setup(4, GPIO.IN, GPIO.PUD_DOWN)
    while True:
    if GPIO.input(4):
    print(“Pressed”)
    

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37. Button polling (pull-up) – GPIO Zero
    button = Button(4)
    while True:
    if button.is_pressed:
    print(“Pressed”)
    

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38. Button polling (pull-down) – GPIO Zero
    button = Button(4, pull_up=False)
    while True:
    if button.is_pressed:
    print(“Pressed”)
    

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39. Button wait_for_edge (pull-up) – RPi.GPIO
    GPIO.setup(4, GPIO.IN, GPIO.PUD_UP)
    while True:
    GPIO.wait_for_edge(4, GPIO.FALLING)
    print(“Pressed”)
    

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40. Button wait_for_edge (pull-down) – RPi.GPIO
    GPIO.setup(4, GPIO.IN, GPIO.PUD_DOWN)
    while True:
    GPIO.wait_for_edge(4, GPIO.RISING)
    print(“Pressed”)
    

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41. Button wait_for_press (pull-up) – GPIO Zero
    button = Button(4)
    while True:
    button.wait_for_press()
    print(“Pressed”)
    

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42. Button wait_for_press (pull-down) – GPIO Zero
    button = Button(4, pull_up=False)
    while True:
    button.wait_for_press()
    print(“Pressed”)
    

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43. Button callback – RPi.GPIO
    GPIO.setup(4, GPIO.IN, GPIO.PUD_UP)
    def pressed(pin):
    print(“Pressed”)
    GPIO.add_event_detect(4, GPIO.FALLING, pressed)
    

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44. Button callback – GPIO Zero
    button = Button(4)
    def pressed():
    print(“Pressed”)
    button.when_pressed = pressed
    

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45. Button callback – RPi.GPIO
    GPIO.setup(4, GPIO.IN, GPIO.PUD_UP)
    def pressed(pin):
    print(“Pin %s Pressed” % pin)
    GPIO.add_event_detect(4, GPIO.FALLING, pressed)
    

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46. Button callback – GPIO Zero
    button = Button(4)
    def pressed(button):
    print(“Pin %s pressed” % button.pin.number)
    button.when_pressed = pressed
    

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47. Button + LED
    from gpiozero import LED, Button
    led = LED(17)
    button = Button(4)
    button.when_pressed = led.on
    button.when_released = led.off
    

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48. LED – PWM – RPi.GPIO
    GPIO.setup(17, GPIO.OUT) # pin 17
    p = GPIO.PWM(17, 100) # pin 17, frequency 100Hz
    p.start(0) # initial duty cycle
    for i in range(101):
    p.ChangeDutyCycle(i)
    sleep(0.01)
    

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49. LED – PWM – GPIO Zero
    from gpiozero import PWMLED
    led = PWMLED(17)
    led.on() # on
    led.off() # off
    led.value = 0.5 # half brightness
    led.pulse() # blink with fade in/out
    

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50. Full colour LED
    from gpiozero import RGBLED
    led = RGBLED(red=2, green=3, blue=4)
    led.red.on() # full red
    led.color = (1, 0, 1) # purple
    led.blue = 0.3 # dim the blue value to 0.3
    # now (1, 0, 0.3)
    

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51. Traffic Lights
    from gpiozero import TrafficLights
    lights = TrafficLights(9, 10, 11)
    lights.on() # all on
    lights.off() # all off
    lights.red.on() # red on
    lights.toggle() # swap state of all lights
    

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52. Traffic Lights sequence
    while True:
    lights.green.on()
    lights.amber.off()
    lights.red.off()
    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()
    

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53. Traffic Lights sequence
    while True:
    lights.value = (1, 0, 0)
    sleep(10)
    lights.value = (0, 1, 0)
    sleep(1)
    lights.value = (0, 0, 1)
    sleep(10)
    lights.value = (0, 1, 1)
    sleep(1)
    

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54. Traffic HAT
    from gpiozero import TrafficHat
    th = TrafficHat()
    th.lights.red.on()
    th.lights.amber.on()
    th.button.when_pressed = th.on
    th.button.when_released = th.off
    

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55. TrafficHat - PWM
    from gpiozero import TrafficHat
    th = TrafficHat(pwm=True)
    th.lights.red.value = 0.2
    th.lights.amber.value = 0.4
    th.lights.green.value = 0.8
    

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56. Motion sensor
    from gpiozero import LED, MotionSensor
    led = LED(2)
    sensor = MotionSensor(3)
    sensor.when_motion = led.on
    sensor.when_no_motion = led.off
    

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57. Light sensor
    from gpiozero import LED, LightSensor
    led = LED(2)
    sensor = LightSensor(3)
    while True:
    sensor.wait_for_light()
    print("It's light!")
    sensor.wait_for_dark()
    print("It's dark")
    

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58. Motor
    from gpiozero import Motor
    from time import sleep
    motor = Motor(forward=17, backward=18)
    while True:
    motor.forward()
    sleep(5)
    motor.backward()
    sleep(5)
    

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59. Robot
    from gpiozero import Robot
    from time import sleep
    robot = Robot(left=(17, 18), right=(22, 23))
    while True:
    robot.forward()
    sleep(10)
    robot.left()
    sleep(1)
    

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60. Pre-configured robot interfaces
    robot = RyanteckRobot()
    robot = CamJamKitRobot()
    

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61. Button controlled Robot
    from gpiozero import RyanteckRobot, Button
    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
    

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62. Picamera
    from picamera import PiCamera
    from gpiozero import Button
    from datetime import datetime
    camera = PiCamera()
    left = Button(4)
    right = Button(5)
    def capture():
    dt = datetime.now().isoformat()
    camera.capture('/home/pi/%s.jpg' % dt)
    left.when_pressed = camera.start_preview
    left.when_released = camera.stop_preview
    right.when_pressed = capture
    

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63. Push button stop motion
    from gpiozero import Button
    from picamera import PiCamera
    camera = PiCamera()
    button = Button(4)
    camera.start_preview()
    frame = 1
    while True:
    button.wait_for_press()
    camera.capture('/home/pi/frame%03d.jpg' % frame)
    frame += 1
    

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64. Analogue - potentiometers
    from gpiozero import MCP3008
    pot = MCP3008()
    while True:
    print(pot.value)
    

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65. Dial up the brightness!
    from gpiozero import PWMLED, MCP3008
    led = PWMLED(2)
    pot = MCP3008()
    while True:
    led.value = pot.value
    

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66. Colour mixing
    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
    

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67. #76 while True: led.red = pot.value
    

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68. #76 while True: led.red = pot.value
    

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69. #76 while True: led.red = pot.value
    

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70. #76 while True: led.red = pot.value
    

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71. Source / Values
    Output Device
    .value
    .values
    .source
    Input Device
    .value
    .values
    

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72. Source / Values
    Output Device
    .value
    .values
    .source
    Input Device
    .value
    .values
    

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73. Dial up the brightness!
    from gpiozero import PWMLED, MCP3008
    led = PWMLED(2)
    pot = MCP3008()
    led.source = pot.values
    

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74. Colour mixing
    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)
    led.red.source = red_pot.values
    led.green.source = green_pot.values
    led.blue.source = blue_pot.values
    

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

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76. Source / Values
    Output Device
    .value
    .values
    .source
    Custom generator
    while True:
    …
    yield value
    

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77. Custom value generators
    blue = PWMLED(16)
    blue.source_delay = 0.1
    blue.source = (i / 10000 for i in range(10000))
    

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78. Custom value generators
    Output Device
    .value
    .values
    .source
    Input Device
    .value
    .values
    Custom generator
    e.g. read_slowly
    

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79. Custom value generators
    def read_slowly(values):
    for i in values:
    yield i
    sleep(0.1)
    blue.source = read_slowly(sensor.values)
    

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80. Source Tools
    Output Device
    .value
    .values
    .source
    Input Device
    .value
    .values
    Source tool
    e.g. invert
    

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81. Source Tools
    from gpiozero import PWMLED, MCP3008
    from gpiozero.tools import inverted
    led = PWMLED(4)
    pot = MCP3008(channel=0)
    led.source = inverted(pot.values)
    

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82. LEDBoard
    from gpiozero import LEDBoard
    from time import sleep
    leds = LEDBoard(2, 3, 4, 5, 6)
    for led in leds:
    led.on()
    sleep(1)
    leds.off()
    

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83. LEDBarGraph
    from gpiozero import LEDBoard
    from time import sleep
    leds = LEDBarGraph(2, 3, 4, 5, 6, 7)
    leds.value = 1/2 # (1, 1, 1, 0, 0, 0)
    leds.value = ­1/2 # (0, 0, 0, 1, 1, 1)
    leds.value = 1/4 # (1, 0, 0, 0, 0, 0)
    

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84. LEDBarGraph - PWM
    from gpiozero import LEDBoard
    from time import sleep
    leds = LEDBarGraph(2, 3, 4, 5, 6, 7, pwm=True)
    leds.value = 1/4 # (1, 0.5, 0, 0, 0, 0)
    leds.value = 3/4 # (1, 1, 1, 1, 0.5, 0)
    

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85. Supporting multiple back-ends
    1) RPi.GPIO
    2) RPIO
    3) pigpio
    4) Native
    

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86. pigpio - remote GPIO from Pi or PC
    from gpiozero import LED
    from gpiozero.pins.pigpiod import PiGPIOPin
    led = LED(PiGPIOPin(12, host='192.168.0.2'))
    led.blink()
    

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87. GPIO Zero Timeline
    ●
    12 Sept – Idea sparked
    ●
    14 Sept – Initial commit on GitHub
    ●
    15 Sept – Named GPIO Zero, first PR, first alpha released on PyPI
    ●
    28 Sept – v0.6 public beta 1
    ●
    25 Oct – v0.9 public beta 4
    ●
    16 Nov – v1.0 released
    ●
    21 Nov – Released in Raspbian Jessie
    ●
    8 Feb – v1.1 released
    ●
    10 Apr – v1.2 released
    

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88. v1.0
    ●
    200 commits
    ●
    2 contributors (+4 minor contributions)
    ●
    103 GitHub issues (53 issues, 50 PRs)
    ●
    4 alpha releases
    ●
    4 beta releases
    ●
    68 days between initial commit and major release
    

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89. v1.3 (a work in progress)
    ●
    522 commits
    ●
    5 contributors (+8 minor contributions)
    ●
    390 GitHub issues (178 issues, 212 PRs)
    

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90. Future development
    ●
    Add more components
    ●
    Probably move default from RPi.GPIO to pigpio
    ●
    Better remote GPIO support
    ●
    Promote use of “gpiozero standard” to allow other modules to
    provide objects which plug-in to gpiozero objects easily (e.g.
    source/values)
    

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91. Install GPIO Zero
    ●
    Pre-installed in Raspbian Jessie since November
    ●
    Update with:
    sudo apt­get update
    ●
    Install with:
    sudo apt­get install python3­gpiozero
    or:
    sudo apt­get install python­gpiozero
    

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92. GPIO Zero
    ●
    gpiozero.readthedocs.io
    – Installation instructions
    – API Documentation
    – Examples
    ●
    GitHub Issues
    – Suggestions
    – Feedback
    ●
    Contact me
    – ben@raspberrypi.org
    – @ben_nuttall on Twitter
    ●
    #gpiozero on Twitter
    

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93. Zero all the things!
    ●
    PyGame Zero
    ●
    GPIO Zero
    ●
    Network Zero
    ●
    BlueZero
    

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94. How can you get involved?
    

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95. www.raspberrypi.org
    ●
    Daily blog articles – news,
    projects and stories
    ●
    OS Downloads
    ●
    Help pages
    ●
    Documentation
    ●
    Community sites
    ●
    Forums
    

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96. Raspberry Pi Learning Resources
    ●
    Teach, Learn and Make
    ●
    Free
    ●
    Open source
    ●
    Creative Commons
    ●
    Created by Raspberry Pi
    Education Team
    ●
    Scratch, Python and more
    

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97. Raspberry Pi Weekly
    ●
    Free weekly email newsletter
    ●
    Raspberry Pi news, projects
    and articles
    ●
    3 years of issues on the
    website
    ●
    raspberrypi.org/weekly
    

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98. The MagPi
    ●
    Community magazine established
    in 2012 (as free PDF download)
    ●
    Now the official Raspberry Pi
    magazine
    ●
    Paper copies on sale in UK shops
    and online
    ●
    Still a free PDF download
    ●
    Occasionally comes with a free
    computer
    ●
    Book series (also available for free)
    

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99. Raspberry Jam in Russia
    ●
    Start a Raspberry Jam in your
    area
    ●
    Create opportunities for kids
    to learn programming
    ●
    Share skills and projects
    ●
    See www.raspberrypi.org/jam
    ●
    Contact me for support
    

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100. Code Club in Russia
     ●
     Translate our projects
     ●
     Run a club for 9-11 year olds
     ●
     Become a country
     coordinator
     ●
     See www.codeclubworld.org
     ●
     Contact me or
     indra@codeclub.org.uk
     

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101. How can you get involved?
     

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