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Physical computing with Python and Raspberry Pi Ben Nuttall Raspberry Pi Foundation UK Charity 1129409

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Ben Nuttall ● Raspberry Pi Community Manager ● Based in Cambridge, UK ● Creator of gpiozero python library ● Columnist on opensource.com ● github.com/bennuttall ● twitter.com/ben_nuttall ● [email protected]

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Over 14 million Raspberry Pis sold

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Raspberry Pi Foundation ● Educational charity founded in 2009 ● Incorporates: – Raspberry Pi Trading Ltd – Code Club – CoderDojo ● Trading profits fund education programmes raspberrypi.org/about

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Our mission “Putting the power of digital making into the hands of people all over the world” So that people are: ● Capable of understanding and shaping an increasingly digital world ● Able to solve the problems that matter to them, both as makers and entrepreneurs ● Equipped for the jobs of the future raspberrypi.org/about

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We do this by providing... ● Low-cost, high-performance computers ● Outreach and education programmes ● Free resources and teacher training p

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Current models ● Raspberry Pi 3 ● 64-bit quad-core ARMv8 @ 1.2GHz ● 1GB RAM ● $35 ● Raspberry Pi Zero / Zero W ● 32-bit single-core ARMv6 @ 1GHz ● 512MB RAM ● $5 / $10 raspberrypi.org/products

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Raspbian Jessie desktop raspberrypi.org/downloads

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Raspbian x86 rpf.io/x86

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Moving on from IDLE... ● We have included a new IDE called Thonny ● We are investing in developing Nicholas Tollervery’s Mu editor – watch this space! ntoll.org/article/mu-pi

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GPIO Pins – General Purpose Input/Output

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Physical computing ● Flashy lights ● Motors & robots ● Photo & video ● Sensors ● Internet of Things ● Home automation

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GPIO ● 3V3, 5V ● GPIO, SPI, I2C, UART ● GPIO = variable 3V3 pinout.xyz

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GPIO components

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Add-on boards / HATs

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

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GPIO Zero supports...

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GPIO Zero Device Hierarchy!

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Multi-paradigm: procedural 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: event-driven 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 = pot.value

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.value >>> led = PWMLED(17) >>> pot = MCP3008() >>> led.value = pot.value >>> while True: ... led.value = pot.value

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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 from gpiozero import LED, Button led = LED(17) button = Button(2) led.source = button.values

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

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Source tools from gpiozero import Button, LED from gpiozero.tools import negated led = LED(4) button = Button(17) led.source = negated(button.values)

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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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AND logic gate from gpiozero import Button, LED from gpiozero.tools import all_values button_a = Button(2) button_b = Button(3) led = LED(17) led.source = all_values(button_a.values, button_b.values)

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CPU Temperature from gpiozero import LEDBarGraph, CPUTemperature cpu = CPUTemperature(min_temp=50, max_temp=90) leds = LEDBarGraph(2, 3, 4, 5, 6, 7, 8, pwm=True) leds.source = cpu.values

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Is the internet working? from gpiozero import LED, PingServer from gpiozero.tools import negated green = LED(17) red = LED(18) google = PingServer('google.com') green.source = google.values green.source_delay = 60 red.source = negated(green.values)

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Energenie

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Energenie tortoise lamp from gpiozero import Energenie, TimeOfDay from datetime import time lamp = Energenie(1) daytime = TimeOfDay(time(8), time(20)) lamp.source = daytime.values

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Supporting multiple pin libraries ● RPi.GPIO ● Implemented in C, current default ● Available in PyPI & apt repository (installed by default in Raspbian) ● RPIO ● Implemented in C, supports hardware PWM, supports Pi 1 only (dead project) ● Available in PyPI ● pigpio ● Python wrapper for C library, supports lots of protocols, runs as daemon, supports remote connections ● Available in PyPI & apt repository (installed by default in Raspbian) ● Native ● Pure Python, limited functionality, experimental ● Included in gpiozero source ● MockPin & MockPWMPin ● Pure Python, used in test suite ● Included in gpiozero source

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pigpio - remote GPIO from Pi or PC

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pigpio - remote GPIO from Pi or PC from gpiozero import LED from gpiozero.pins.pigpio import PiGPIOFactory from signal import pause factory = PiGPIOFactory('192.168.0.2') led = LED(22, pin_factory=factory) led.blink() pause()

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pigpio - remote GPIO from Pi or PC $ export GPIOZERO_PIN_FACTORY=pigpio $ export PIGPIO_ADDR=192.168.0.2 $ python3 led.py from gpiozero import LED from signal import pause led = LED(22) led.blink() pause()

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MockPin $ GPIOZERO_PIN_FACTORY=mock python3 >>> from gpiozero import LED >>> led = LED(22) >>> led.blink() >>> led.value True >>> led.value False

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MockPin >>> from gpiozero import LED >>> led = LED(22) >>> button = Button(23) >>> led.source = button.values >>> led.value False >>> button.pin.drive_low() >>> led.value True

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pinout command line tool

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Sense HAT ● Special made for Tim Peake's Astro Pi mission ● Sensors, LED display & joystick ● Great for science, games and creativity ● Works on any Pi model ● Emulators also available raspberrypi.org/products/sense-hat

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Sense HAT

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Sense HAT >>> from sense_hat import SenseHat >>> sense = SenseHat() >>> sense.show_message(“Hello world”)

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Sense HAT >>> sense.temperature 25.0 >>> sense.humidity 45.0 >>> sense.accelerometer {'pitch': 0.0, 'roll': 0.0, 'yaw': 0.0} >>> sense.gyroscope {'pitch': 0.0, 'roll': 0.0, 'yaw': 0.0} >>> sense.orientation {'pitch': 0.0, 'roll': 0.0, 'yaw': 0.0}

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Sense HAT from sense_hat import SenseHat sense = SenseHat() while True: r = 255 * sense.humidity / 100 sense.clear(r, 0, 0) pythonhosted.org/sense-hat

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Astro Pi: Your code in space astro-pi.org

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Sense HAT Web Emulator trinket.io/sense-hat

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Sense HAT Desktop Emulator sense-emu.readthedocs.io

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Picamera ● 8 megapixels (v2) – v1 was 5mpx ● Visible light & infra-red versions available ● 1080p30, 720p60 and VGA90 video ● Command line interface and Python library raspberrypi.org/products/camera-module-v2

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Picamera - capture from picamera import PiCamera from time import sleep camera = PiCamera() camera.start_preview() sleep(3) camera.capture('/home/pi/Desktop/image.jpg') camera.stop_preview()

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Picamera – record video from picamera import PiCamera from time import sleep camera = PiCamera() camera.start_preview() camera.start_recording('/home/pi/video.h264') sleep(10) camera.stop_recording() camera.stop_preview()

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Picamera + GPIO push button from picamera import PiCamera from gpiozero import Button camera = PiCamera() button = Button(17) camera.start_preview() button.wait_for_press() camera.capture('/home/pi/Desktop/image.jpg') camera.stop_preview()

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Picamera image effects from picamera import PiCamera from time import sleep camera = PiCamera() camera.start_preview() for effect in camera.IMAGE_EFFECTS: camera.image_effect = effect camera.annotate_text = effect sleep(1) camera.stop_preview()

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Picamera image effects

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Web Streaming github.com/waveform80/pistreaming

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Picamera + OpenCV pyimagesearch.com

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Read the docs! ● gpiozero.readthedocs.io ● pythonhosted.org/sense-hat ● sense-emu.readthedocs.io ● picamera.readthedocs.io

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Google AIY Projects kit ● Free with The MagPi #57 ● Google Voice HAT + speaker ● Google assistant ● Write code to process custom voice commands – “Lights on” – “Robot go forward” – “Take a picture” aiyprojects.withgoogle.com

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PyPI & ARM Wheels ● PyPI doesn’t support uploading ARM wheels :( ● I have a project called piwheels – I build all PyPI packages on a Raspberry Pi 3 – I host a Python package repository on the same Pi ● Next gen PyPI (warehouse) now supports uploading ARM wheels :) ● See my lightning talk slides at speakerdeck.com/bennuttall ● See the project at github.com/bennuttall/piwheels github.com/bennuttall/piwheels

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How you can get involved...

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Python libraries ● Play with, and contribute to: – gpiozero – picamera – sense hat – more! ● Help maintainers upgrade modules to Python 3 ● Create your own Python libraries for Raspberry Pi things

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

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Raspberry Jam ● Independently organised community events ● Family-friendly ● Mix of meetup / conference / workshop styles ● Raspberry Jam Guidebook and more resources available ● Contact me about setting one up! raspberrypi.org/jam

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Raspberry Jam near you? raspberrypi.org/jam

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Code Club ● Free volunteer-led after school clubs for children ● Projects provided using Scratch, HTML and Python ● Training and support provided for volunteers ● Help translating materials codeclubworld.org

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Physical computing with Python and Raspberry Pi Ben Nuttall Raspberry Pi Foundation UK Charity 1129409