Pi GPIO Connect an LED

Connecting an LED to a GPIO and turning it on is probably one of the most simple things that we can use the Pi GPIO for. There is however a bit of thought that needs to go in to it so that we do not damage anything.


 

We will need the following :

  • Pi with a GPIO
  • LED
  • 220ohm Resistor(red, red, black, black or any larger up to ~1k)
  • Jumper wires

Strictly speaking we should calculate the correct value for the resistor but 220ohm or above will be fine for both 3.3v RPi GPIO output and 5v if required.

I have chosen GPIO21 (Pin40) as the output and the resistor is in series with the LED. The short leg of the LED goes towards ground.

 


 

Create a new python script "nano led.py"

import RPi.GPIO as GPIO
import time

GPIO.setmode(GPIO.BCM) #Board is Physical pin 1-40, BCM is GPIO NN
GPIO.setup(21, GPIO.OUT) #Sets GPIO 21 to output mode
GPIO.output(21, GPIO.HIGH) #Sets GPIO 21 High +3.3v
time.sleep(5) #Sleep / Wait for 5 seconds
GPIO.output(21, GPIO.LOW) #Sets GPIO 21 Low 0v
GPIO.cleanup() #Releases GPIO good practice.

Run it using "python led.py"

Your LED should go on for 5 seconds and then turn off.


Adding additional LED's is just a case of using an additional GPIO.

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