Interfacing of Switch with LPC2148 microcontroller

Now, i discuss a program of LPC2148 microcontroller interfaced with a Switch and a LED. Earlier, i have discussed about the functions of LPC2148 microcontroller and its registers, which can help you understand the program described below. And, you also can understand the debouncing concept of switch when interfaced with microcontroller (click here)

Program:

	#include <LPC214X.H>
	int temp;
	int z;
	//***************************************
	void delay(int z)
	{
	int x,y;
	for(x=0;x<=2400;x++)
	{
	for(y=0;y<=z;y++);
	}
	}
	//****************************************
	void check_set(int a, int b)
	{
	temp=IOPIN0;
	if((temp&a)==0)
	{
	if((b&IOPIN0)!=0)
	{
	IOCLR0=b;
	delay(400);
	}
	else
	{
	IOSET0=b;
	delay(400);
	}
	temp=IOPIN0;
	while((temp&a)==0)
	{
	temp=IOPIN0;
	}
	delay(400);
	}
	}
	//*****************************************************
	int main(void)
	{
	int x,a,b;
	IODIR0=0x000000FF;
	IOCLR0=0x000000FF;
	delay(1000);
	while(1)
	{
	a=0x00008000;
	b=0x00000001;
	for(x=0;x<=7;x++)
	{
	check_set(a,b);
	a=a>>1;
	b=b<<1;
	}
	}
	}

view raw Switch with LPC214X hosted with ❤ by GitHub

Theory:

IOPIN is the Input/Output Pin configuration which defines the current state of the GPIO configured port pins that can always be read from this register, regardless of pin direction. The denouncing switch concept has been implemented in this example code in which LED is switched on whenever a switch connected on port P0 is pressed.