Relay control using Raspberry Pi

Raspberry Pi relay control

Operating the relay with the Raspberry Pi has several important advantages. For example, we can program the control of electrical devices in the house and thus create the basic functions of an intelligent building.

In this example we will use it:

Connection

The two devices shall be combined as shown in the table below

GPIO Raspberry Pi Relay
5 V VCC
GND GND

GPIO 1

(any pin can be used)

 IN1

We connect any device we intend to control to the relay contacts, e.g. an LED bar. In the example we will use an ordinary diode with separate power supply. The power supply for the diode is connected via the relay contacts:

Operation

To use the GPIO pins in Raspberry we need a library that allows us to do so. For this we will use the wiringPi library. Description how to download and install it can be found here. Just copy the next commands. Finally, to check the correctness of the installation, type in:

  • gpio readall

After this command we should see the table below:

Now we will write a simple program. We create the led.c file

  • nano led.c

The file should contain the following program:

#include 

int main (void)
{
 wiringPiSetup ();
  int pin = 1 ;

 pinMode (pin, OUTPUT) ;
 while(1){
      digitalWrite (pin, HIGH) ;
      delay (1000);
      digitalWrite (pin, LOW);
      delay (1000);
 }
  return 0 ;
}

Then save the changes to the file and close it. To compile the created file we use the command:

  • gcc -Wall -o indicator led.c-lwiringPi

To start the program, enter:

  • sudo ./led

The program alternately turns on and off the diode every 1 second. Thanks to this project we can understand the basic operation of GPIO in the Raspberry Pi and the use of relays.

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