Program to interface Relay with LPC2148 microcontroller

A relay is an electrically operated switch or an electro-mechanical switch. Relays are used where it is necessary to control an electronic circuit by a low-power signal or where several circuits must be controlled by one signal.

Principle: 

Current flowing through the coil of the relay creates a magnetic field which attracts a lever and changes the switch contacts. The coil current can be on or off so relays have two switch positions and most have double throw (changeover) switch contacts.

Program:

	#include <LPC214X.H>
	#define R1 0x00000010
	#define R2 0x00000020
	//***************************************
	void delay(int z)
	{
	int x,y;
	z=z*5;
	for(x=0;x<=2400;x++)
	{
	for(y=0;y<=z;y++);
	}
	}
	//*****************************************************
	int main(void)
	{
	IODIR0=0x00000030;
	IOCLR0=0x00000030;
	while(1)
	{
	IOSET0=R1;
	IOCLR0=R2;
	delay(1000);
	IOSET0=R2;
	IOCLR0=R1;
	delay(1000);
	}
	}

view raw Relay with LPC2148 hosted with ❤ by GitHub

Theory:

A relay is used for electronic to electrical interfacing i.e. it is used to switch on or off electrical circuits operating at high AC voltage using a low DC control voltage. A relay generally has two parts, a coil which operates at the rated DC voltage and a mechanically movable switch. The electronic and electrical circuits are electrically isolated but magnetically connected to each other. In this R1 and R2 are the connection of relay made with LPC2148 and signal applied on this R1 and R2 signal to control relay.