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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 11 million Raspberry Pis sold

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Raspberry Pi Foundation ● Educational charity founded in 2009 ● Owns trading subsidiary Raspberry Pi Trading Ltd ● Trading profits fund educational programmes

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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

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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 ● 32-bit single-core ARMv6 @ 1GHz ● 512MB RAM ● $5

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Raspbian Jessie with PIXEL

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PIXEL x86

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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 ● Engaging and empowering

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

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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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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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GPIO Zero supports...

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GPIO Zero Device Hierarchy!

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Supporting multiple back-ends ● RPi.GPIO ● Implemented in C, current default ● RPIO ● Implemented in C ● pigpio ● Python wrapper for C library, runs as daemon, remote pins ● Native ● Pure Python, limited functionality, experimental ● MockPin & MockPWMPin ● Pure Python, used in test suite

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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.pigpiod import PiGPIOPin led = LED(PiGPIOPin(22, host='192.168.0.2')) led.blink()

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

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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

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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: %s" % effect sleep(5) camera.stop_preview()

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Picamera image effects

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Web Streaming

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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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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

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Sense HAT

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Sense HAT >>> from sense_hat import SenseHat >>> sense = SenseHat() >>> sense.show_message(“Hello world”) >>> sense.temperature >>> sense.humidity >>> sense.accelerometer >>> sense.gyroscope >>> sense.orientation

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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)

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Astro Pi: Your code in space

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Sense HAT Web Emulator

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Sense HAT Desktop Emulator

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

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How you can get involved...

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Python libraries ● 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 ● Contact me about setting one up! ● 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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Python and Raspberry Pi Ben Nuttall Raspberry Pi Foundation UK Charity 1129409