Interfacing LED with Raspberry Pi GPIO Pin
Requirement:
1.Breadboard
2.LED
3.Jumper Wire
4.330 ohm resistor
5.wiringPi library to write program in c
First we need to install wiringPi library as below:
Library install:
We are writing the program in c for that we need to install the library. To install follow the below steps:
1.Install Git Core
Git Core need to be installed to download wiringPi library
Command to install
sudo apt-get install git-core
2.Command to download wiringPi:
git clone git://git.drogon.net/wiringPi
3.Built and install wiringPi library:
Go to library as
cd wiringPi
Run command : ./built
Instruction to glow LED:
1.Understand the GPIO structure
For that type the command pinout on terminal
2.As we are using wiringPi library then refer GPIO structure
For that type the command gpio readall on terminal
Refer below diagram
Circuit Building:
1.Connect any GPIO pin of Raspberry Pi (Ex:GPIO25 in wPi it’s 6 refer in above table) to anode of LED through jumper wire and breadboard
2.Connect any Ground pin of Raspberry Pi to cathode of LED through jumper wire and breadboard
3.Connect one leg of resistor to cathode of LED and another leg of resistor to ground
As shown below
Now connect all the peripherals of raspberry pi and power on the supply
Programming:
1.Open the terminal in that open a vi file to write c code
Ex: vi blink_led.c
2.Type the following code in vi blink_led.c
/* Program to blink led using GPIO pin of raspberry pi
Author: PTI Date:02/07/18*/
#include <stdio.h>
#include <wiringPi.h> //to include wiringPi library
#define PIN25 6
int main()
{
if(wiringPiSetup() == -1) //function to setup wiringPi
{
printf(“Cannot setup wiringPi\n”);
return 0;
}
pinMode(PIN25, OUTPUT); //set output pin
while(1)
{
digitalWrite(PIN25, HIGH); //To make GPIO pin high
printf(“led on\n”);
delay(1000);
digitalWrite(PIN25, LOW); //To make GPIO pin low
printf(“led off\n”);
delay(1000);
}
return 0;
}
3.Once writing program is done save it
4.compile the program as show below
gcc blink_led.c -o blink_led -lwiringPi
-lwiringPi is given to tell compiler we are using wiringPi library because compiler by default search in standard library
5.Run the executable file
sudo ./blink_led
Glow led through command line:
Led can also be glow through command line as shown
Now i have connect led to GPIO25
pi@raspberrypi:~$ echo 25 > /sys/class/gpio/export
pi@raspberrypi:~$ cd /sys/class/gpio/gpio25
pi@raspberrypi:/sys/class/gpio/gpio25# echo out > direction
pi@raspberrypi:/sys/class/gpio/gpio25# echo 1 > value
Now led will glow
To turn off the led
pi@raspberrypi:/sys/class/gpio/gpio25# echo 0 >value