Programming paradigms for physical computing and IoT

Transcript

1. 1.

   Programming paradigms for physical computing and IoT Ben Nuttall Raspberry

   Pi Foundation UK Charity 1129409
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   GPIO Pins – General Purpose Input/Output

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   GPIO Zero – a friendly API for GPIO devices from

   gpiozero import LED led = LED(2) led.blink()
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   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
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   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()
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   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()
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   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
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   Multi-paradigm: declarative from gpiozero import LED, Button led = LED(17)

   button = Button(4) led.source = button.values
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   .value >>> led = PWMLED(17) >>> led.value 0.0 >>> led.on()

   >>> led.value 1.0 >>> led.value = 0
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    .value >>> led = PWMLED(17) >>> pot = MCP3008() >>>

    led.value 0.0 >>> pot.value 0.008130081300813009 >>> led.value = pot.value
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    .value >>> while True: ... led.value = pot.value

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

    0.008130081300700108 0.008130081300414001
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    Source / Values Output Device .value .values .source Input Device

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

    .value .values
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    Source / Values LED Button

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    Source / Values from gpiozero import LED, Button led =

    LED(17) button = Button(2) led.source = button.values
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    Source / Values PWM LED Potentiometer

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

    .values function
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    Processing values LED negated Button

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

    negated led = LED(4) btn = Button(17) led.source = negated(btn.values)
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    Source tools – single source conversions • absoluted • booleanized

    • clamped • inverted • negated • post_delayed • post_periodic_fltered • pre_delayed • pre_periodic_fltered • quantized • queued • smoothed • scaled
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    Combining values Output Device .value .values .source Input Device .value

    .values Source tool Input Device .value .values
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    Combining values LED Button all_values Button

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    Source tools – combining sources • all_values • any_values •

    averaged • multiplied • summed
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    Chaining combined values LED Motion sensor all_values Light sensor booleanized

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

    = None
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    Artifcial values Output Device .value .values .source function

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    Source tools – artifcial sources • alternating_values • cos_values •

    ramping_values • random_values • sin_values
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    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
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    Blue Dot

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    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()
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    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()
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    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
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    Multi-paradigm: declarative from gpiozero import LED from bluedot import BlueDot

    led = LED(17) bd = BlueDot() led.source = bd.values
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    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
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    Z-Wave devices & asyncio

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    GPIO Zero on GitHub & ReadTheDocs

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    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
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    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
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    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
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    Programming paradigms for physical computing and IoT Ben Nuttall Raspberry

    Pi Foundation UK Charity 1129409