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GPIO and Python (3/9) - Blinking LED

In this project you’ll learn how to make a LED blink!

Things you will need:

Raspberry Pi + SD Card
Keyboard + Mouse
Monitor + HDMI Cable
Power Supply
Breadboard
1x Red LED
1x Blue LED
2x 330? Resistor
3x M/F Jumper Wire

Prerequisites:

Latest version of Rasbian installed on your SD Card
Raspberry Pi setup with a keyboard, mouse and monitor

1. Change the current directory to our gpio_python_code directory:

cd gpio_python_code 

2. Start by creating a file for our blink led script

touch 3_blink.py

3. Create a file for our blink led forever script

touch 3_blink_forever.py

4 . Edit the 3_blink.py script using nano 3_blink.py add the following code:

#!/usr/bin/python



from time import sleep # import the time function from the sleep library

import RPi.GPIO as GPIO # import our GPIO library



GPIO.setmode(GPIO.BCM) # set the board numbering system to BCM



# setup our output pins

GPIO.setup(17,GPIO.OUT)

GPIO.setup(27,GPIO.OUT)



# Turn LEDs on

print “lights on”

GPIO.output(17,GPIO.HIGH)

GPIO.output(27,GPIO.HIGH)

sleep(1) # sleep for 1 second



# Turn LEDs off

print “lights off” 

GPIO.output(17,GPIO.LOW)

GPIO.output(27,GPIO.LOW)

sleep(1)



# Turn LEDs on

print “lights on”

GPIO.output(17,GPIO.HIGH)

GPIO.output(27,GPIO.HIGH) 

sleep(1)



# Turn LEDs off

print “lights off”

GPIO.output(17,GPIO.LOW)

GPIO.output(27,GPIO.LOW)

GPIO.cleanup() # the clean-up function will reset all the configurations made in this script. This will stop the warnings we got from the tutorial 2.

5. Edit the 3_blink_forever.py script using nano 3_blink_forever.py add the following code:

#!/usr/bin/python



# import libraries

from time import sleep

import RPi.GPIO as GPIO



GPIO.setmode(GPIO.BCM) # set pin numbering system to bcm



# setup our output pins

GPIO.setup(17,GPIO.OUT)

GPIO.setup(27,GPIO.OUT)



# create an infinite loop

while True:

    # turn leds on

    print “lights on”

    GPIO.output(17,GPIO.HIGH)

    GPIO.output(27,GPIO.HIGH)



    sleep(1) # sleep 1 second



    # turn leds off

    print “lights off”

    GPIO.output(17,GPIO.LOW)

    GPIO.output(27,GPIO.LOW)

    sleep(1) # sleep 1 second

6. Execute your 3_blink.py script

sudo python 3_blink.py

7. Execute your 3_blink_forever.py script

sudo python 3_blink_forever.py

8. To stop your 3_blink_forever.py script, simply press ctrl+c



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