Programming paradigms for physical computing and IoT

Transcript

1. Programming paradigms for physical computing and IoT Ben Nuttall Raspberry

   Pi Foundation UK Charity 1129409

2. GPIO Pins – General Purpose Input/Output

3. GPIO Zero – a friendly API for GPIO devices from

   gpiozero import LED led = LED(2) led.blink()

4. GPIO Zero – a friendly API for GPIO devices •

   Zero-boilerplate Pythonic library • Intended for use in education • Simple, guessable API with commonly used names and sensible default values • Simple introduction, smooth learning curve • Multi-paradigm • Extendable

5. Multi-paradigm: procedural (polling) from gpiozero import LED, Button led =

   LED(17) button = Button(4) while True: if button.is_pressed: led.on() else: led.off()

6. Multi-paradigm: procedural (blocking) from gpiozero import LED, Button led =

   LED(17) button = Button(4) while True: button.wait_for_press() led.on() button.wait_for_release() led.off()

7. Multi-paradigm: event-driven (callbacks) from gpiozero import LED, Button led =

   LED(17) button = Button(4) button.when_pressed = led.on button.when_released = led.off

8. Multi-paradigm: declarative from gpiozero import LED, Button led = LED(17)

   button = Button(4) led.source = button.values

9. .value >>> led = PWMLED(17) >>> led.value 0.0 >>> led.on()

   >>> led.value 1.0 >>> led.value = 0

10. .value >>> led = PWMLED(17) >>> pot = MCP3008() >>>

    led.value 0.0 >>> pot.value 0.008130081300813009 >>> led.value = pot.value

11. .value >>> while True: ... led.value = pot.value

12. .values >>> for v in pot.values: ... print(v) 0.008130081300813009 0.008130081300675679

    0.008130081300700108 0.008130081300414001

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

    .value .values

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

    .value .values

15. Source / Values LED Button

16. Source / Values from gpiozero import LED, Button led =

    LED(17) button = Button(2) led.source = button.values

17. Source / Values PWM LED Potentiometer

18. Processing values Output Device .value .values .source Input Device .value

    .values function

19. Processing values LED negated Button

20. Source tools from gpiozero import Button, LED from gpiozero.tools import

    negated led = LED(4) btn = Button(17) led.source = negated(btn.values)

21. Source tools – single source conversions • absoluted • booleanized

    • clamped • inverted • negated • post_delayed • post_periodic_fltered • pre_delayed • pre_periodic_fltered • quantized • queued • smoothed • scaled

22. Combining values Output Device .value .values .source Input Device .value

    .values Source tool Input Device .value .values

23. Combining values LED Button all_values Button

24. Source tools – combining sources • all_values • any_values •

    averaged • multiplied • summed

25. Chaining combined values LED Motion sensor all_values Light sensor booleanized

26. Chaining combined values – garden light prototype from gpiozero import

    LED, LightSensor, MotionSensor from gpiozero.tools import all_values, booleanized garden = LED() light = LightSensor() motion = MotionSensor() garden.source = all_values(booleanized(light.values, 0, 0.1), motion.values)

27. Use source/values in your library from somelib import GardenLight, LightSensor,

    MotionSensor from gpiozero.tools import all_values, booleanized garden = GardenLight() light = LightSensor() motion = MotionSensor() garden.source = all_values(booleanized(light.values, 0, 0.1), motion.values)

28. Combining paradigms while True: light.wait_for_dark() garden.source = motion.values light.wait_for_light() garden.source

    = None

29. Artifcial values Output Device .value .values .source function

30. Source tools – artifcial sources • alternating_values • cos_values •

    ramping_values • random_values • sin_values

31. Energenie tortoise lamp from gpiozero import Energenie, TimeOfDay from datetime

    import time lamp = Energenie(1) daytime = TimeOfDay(time(9), time(18)) lamp.source = daytime.values

32. Blue Dot

33. Multi-paradigm: procedural (polling) from gpiozero import LED from bluedot import

    BlueDot led = LED(17) bd = BlueDot() while True: if bd.is_pressed: led.on() else: led.off()

34. Multi-paradigm: procedural (blocking) from gpiozero import LED from bluedot import

    BlueDot led = LED(17) bd = BlueDot() while True: bd.wait_for_press() led.on() bd.wait_for_release() led.off()

35. Multi-paradigm: event-driven (callbacks) from gpiozero import LED from bluedot import

    BlueDot led = LED(17) bd = BlueDot() bd.when_pressed = led.on bd.when_released = led.off

36. Multi-paradigm: declarative from gpiozero import LED from bluedot import BlueDot

    led = LED(17) bd = BlueDot() led.source = bd.values

37. BlueDot Robot def move(pos): if pos.top: robot.forward(pos.distance) elif pos.bottom: robot.backward(pos.distance)

    elif pos.left: robot.left(pos.distance) elif pos.right: robot.right(pos.distance) bd.when_pressed = move bd.when_moved = move bd.when_released = robot.stop

38. Z-Wave devices & asyncio

39. GPIO Zero on GitHub & ReadTheDocs

40. piwheels • Python package repository providing Arm platform wheels for

    Raspberry Pi • Builds automated from PyPI releases, plus manual builds e.g. opencv & tensorfow • Raspbian is pre-confgured to use piwheels.org as an additional index to PyPI • Massively reduces pip install time for Raspberry Pi users (saved 23 years of build time in 10 months) • Natively compiled on Raspberry Pi 3 hardware (Mythic Beasts Pi cloud) • Repo hosted on single Raspberry Pi serving 400-500k packages per month

41. Raspberry Jam • Independently organised community events around the world

    • Family-friendly • Mix of meetup / conference / workshop styles • Makers, hackers, programmers & beginners come together • Find one near you – or start your own! • raspberrypi.org/jam

42. CoderDojo • Free coding clubs for young people • Find

    one near you and volunteer as a mentor – or start a new Dojo in your area • coderdojo.com

43. Programming paradigms for physical computing and IoT Ben Nuttall Raspberry

    Pi Foundation UK Charity 1129409