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
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
3. Raspberry Pi
4. Raspberry Pi Foundation • Educational charity founded in 2006 • Owns trading subsidiary Raspberry Pi Trading Ltd • Trading profits fund educational programmes
5. A Computer (1981)
6. A Computer (2010)
7. Prototypes
8. Raspberry Pi (2012) Raspberry Pi Model B 700MHz single core 32-bit CPU VideoCoreIV 3D GPU 256MB RAM $35
9. Raspberry Pi Community
10. Raspberry Jam
11. Raspberry Jam raspberrypi.org/jam
12. Made in the UK • Since 2013, Raspberry Pi has been manufactured by Sony in Wales • 20k units per day at peak
13. Raspberry Pi Compute Module Prototyping development board Build your product around the Raspberry Pi
14. Raspberry Pi Zero (2015) 1GHz single core 32-bit CPU VideoCoreIV 3D GPU 512MB RAM $5
15. Raspberry Pi 3 Model B (2016) 1.2GHz quad core 64-bit CPU VideoCoreIV 3D GPU 1GB RAM $35
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
17. Raspberry Pi Foundation Mission “Putting the power of digital making into the hands of people all over the world”
18. Raspberry Pi computers • We produce low-cost high- power computers • They keep getting better and/or cheaper :) • Used in – education – hobby projects – industry
19. Raspberry Pi in Schools
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
21. Raspbian
22. Raspbian • Launch programming applications • Web browser • Preferences and settings • Shutdown & reboot • Look – it's a real computer!
23. Physical computing • Flashy lights • Motors & robots • Photo & video • Sensors • Internet of Things • Engaging and empowering
24. GPIO Pins – General Purpose Input/Output
25. GPIO components
26. Add-on boards / HATs
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)
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...
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
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)
31. Python - GPIO Zero from gpiozero import LED led = LED(17) led.blink()
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
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
34. GitHub
35. Button polling (pull-up) – RPi.GPIO GPIO.setup(4, GPIO.IN, GPIO.PUD_UP) while True: if not GPIO.input(4): print(“Pressed”)
36. Button polling (pull-down) – RPi.GPIO GPIO.setup(4, GPIO.IN, GPIO.PUD_DOWN) while True: if GPIO.input(4): print(“Pressed”)
37. Button polling (pull-up) – GPIO Zero button = Button(4) while True: if button.is_pressed: print(“Pressed”)
38. Button polling (pull-down) – GPIO Zero button = Button(4, pull_up=False) while True: if button.is_pressed: print(“Pressed”)
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”)
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”)
41. Button wait_for_press (pull-up) – GPIO Zero button = Button(4) while True: button.wait_for_press() print(“Pressed”)
42. Button wait_for_press (pull-down) – GPIO Zero button = Button(4, pull_up=False) while True: button.wait_for_press() print(“Pressed”)
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)
44. Button callback – GPIO Zero button = Button(4) def pressed(): print(“Pressed”) button.when_pressed = pressed
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)
46. Button callback – GPIO Zero button = Button(4) def pressed(button): print(“Pin %s pressed” % button.pin.number) button.when_pressed = pressed
47. Button + LED from gpiozero import LED, Button led = LED(17) button = Button(4) button.when_pressed = led.on button.when_released = led.off
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)
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
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)
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
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()
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)
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
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
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
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")
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)
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)
60. Pre-configured robot interfaces robot = RyanteckRobot() robot = CamJamKitRobot()
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
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
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
64. Analogue - potentiometers from gpiozero import MCP3008 pot = MCP3008() while True: print(pot.value)
65. Dial up the brightness! from gpiozero import PWMLED, MCP3008 led = PWMLED(2) pot = MCP3008() while True: led.value = pot.value
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
67. #76 while True: led.red = pot.value
68. #76 while True: led.red = pot.value
69. #76 while True: led.red = pot.value
70. #76 while True: led.red = pot.value
71. Source / Values Output Device .value .values .source Input Device .value .values
72. Source / Values Output Device .value .values .source Input Device .value .values
73. Dial up the brightness! from gpiozero import PWMLED, MCP3008 led = PWMLED(2) pot = MCP3008() led.source = pot.values
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
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 )
76. Source / Values Output Device .value .values .source Custom generator while True: … yield value
77. Custom value generators blue = PWMLED(16) blue.source_delay = 0.1 blue.source = (i / 10000 for i in range(10000))
78. Custom value generators Output Device .value .values .source Input Device .value .values Custom generator e.g. read_slowly
79. Custom value generators def read_slowly(values): for i in values: yield i sleep(0.1) blue.source = read_slowly(sensor.values)
80. Source Tools Output Device .value .values .source Input Device .value .values Source tool e.g. invert
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)
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()
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)
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)
85. Supporting multiple back-ends 1) RPi.GPIO 2) RPIO 3) pigpio 4) Native
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()
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
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
89. v1.3 (a work in progress) • 522 commits • 5 contributors (+8 minor contributions) • 390 GitHub issues (178 issues, 212 PRs)
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)
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
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
93. Zero all the things! • PyGame Zero • GPIO Zero • Network Zero • BlueZero
94. How can you get involved?
95. www.raspberrypi.org • Daily blog articles – news, projects and stories • OS Downloads • Help pages • Documentation • Community sites • Forums
96. Raspberry Pi Learning Resources • Teach, Learn and Make • Free • Open source • Creative Commons • Created by Raspberry Pi Education Team • Scratch, Python and more
97. Raspberry Pi Weekly • Free weekly email newsletter • Raspberry Pi news, projects and articles • 3 years of issues on the website • raspberrypi.org/weekly
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)
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
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
101. How can you get involved?