RaspberryPi GPIO

From Media Design: Networked & Lens-Based wiki
Jump to navigation Jump to search

Raspberry Pi GPIO pins configuration

A 40-pin GPIO header is found on all current Raspberry Pi boards (unpopulated on Pi Zero and Pi Zero W). Prior to the Pi 1 Model B+ (2014), boards comprised a shorter 26-pin header

Pins

  • GPIO is your standard pins that simply be used to turn devices on and off. For example, a LED.
  • I2C (Inter-Integrated Circuit) pins allow you to connect and talk to hardware modules that support this protocol (I2C Protocol). This protocol will typically take up two pins.
  • SPI (Serial Peripheral Interface Bus) pins can be used to connect and talk to SPI devices. Pretty much the same as I2C but makes use of a different protocol.
  • UART (Universal asynchronous receiver/transmitter) is the serial pins used to communicate with other devices.
  • DNC stands for do not connect, this is pretty self-explanatory.
  • The power pins pull power directly from the Raspberry Pi.
  • GND are the pins you use to ground your devices. It doesn’t matter which pin you use as they are all connected to the same line.

40-pin GPIO

PI-GPIO40.png

26 pin (Pi 1)

PI-GPIO26.png

Install

To program the GPIO pins we needed to install the Python3 Rpi.GPIO library

sudo apt-get update
sudo apt-get install python3-rpi.gpio

See RPi.GPIO Documentation

Test: Writing to PIN

In this small script we will write HIGH & LOW values to Pin 12.

And use a LED and a 220Ω resistor to see if GPIO is operating and expecting.

Connect according to the diagram, keeping in mind that the

  • LED has polarity:
    • long leg: positive
    • short leg: negative
  • LED needs to have (220Ω) resistor, standing between its negative leg and 0Volts, in order to protect it from excessive current.

Raspberry-Pi-GPIO-simple-led-circuit.jpg


#!/usr/bin/env python3                                                                                
import RPi.GPIO as GPIO
import time

LedPin = 4
GPIO.setmode(GPIO.BOARD)       # Numbers pins by physical location                                    
GPIO.setup(LedPin, GPIO.OUT)   # Set pin mode as output                                               

try:
    while True:
        GPIO.output(LedPin, GPIO.HIGH)
        time.sleep(1)
        GPIO.output(LedPin, GPIO.LOW)
        time.sleep(1)
except KeyboardInterrupt: # Ctl-C will interrup                                                       
    pass
GPIO.cleanup()  # clean resources used

Links

https://pimylifeup.com/raspberry-pi-gpio/