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

26 pin (Pi 1)

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

or

pip3 install RPi.gpio

See RPi.GPIO at pypi.org

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.

#!/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/
Basic usage: https://sourceforge.net/p/raspberry-gpio-python/wiki/BasicUsage/
Working with inputs (a button for example): https://sourceforge.net/p/raspberry-gpio-python/wiki/Inputs/

RaspberryPi GPIO

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