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GPIO & Python (3/9) - Blinking LED

February 21, 2017

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 330Ω 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

Last update: February 22, 2017

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