Led blinking is one of the beginner circuits which helps one to get acquainted with GPIO pins of Raspberry Pi. Here we use Python language to write the code for blinking Led at one second intervals.

Components required

• One led
• 100 ohm resistor
• Jumper cables

Raspberry Pi GPIO Specifications

• Output Voltage : 3.3V
• Maximum Output Current : 16mA per pin with total current from all pins not exceeding 50mA

For controlling a Led using Raspberry Pi, both python and the GPIO library is needed.

Installing Python GPIO Library

Note: Python and GPIO library are preinstalled if you are using Raspbian.

• Make sure your Rasperry Pi is connected to the internet using either a LAN cable or a WiFi adapter.
• Open the terminal by double clicking the LXTerminal icon
• Type the following command to download the GPIO library as a tarball

        wget http://raspberry-gpio-python.googlecode.com/files/RPi.GPIO-0.4.1a.tar.gz

• Unzip the tarball

        tar zxvf RPi.GPIO-0.4.1a.tar.gz

• Change the directory to unzipped location

        cd RPi.GPIO-0.4.1a

• Install the GPIO library in python

        sudo python setup.py install

Raspberry Pi GPIO Pin Out

Raspberry Pi has 17 GPIO pins out of 26 pins

Circuit Diagram

• Connect the Led to 6 (ground) and 11 (gpio) with a 100Ω resistor in series

Python Programming

• Open Terminal
• Launch IDLE IDE by typing

sudo idle

This launches IDLE with superuser privileges which is necessary execute scripts for controlling the GPIO pins

• After the IDLE launches, open a new window by FILE>OPEN or Ctrl+N

• Type the code below in the window

import time
import RPi.GPIO as GPIO       ## Import GPIO library
GPIO.setmode(GPIO.BOARD)      ## Use board pin numbering
GPIO.setup(11, GPIO.OUT)      ## Setup GPIO Pin 11 to OUT
while True:
	GPIO.output(11,True)  ## Turn on Led
	time.sleep(1)         ## Wait for one second
	GPIO.output(11,False) ## Turn off Led
	time.sleep(1)         ## Wait for one second

• Save the code by FILE>SAVE or Ctrl+S

• To run your code RUN>RUN or Ctrl+F5

• The Led will start blinking now.

Video