//A Sample code for switching a port pin PA0 high for 0.5 seconds and low  //for 0.5 seconds
#include <ioavr.h>	//This includes appropriate header file for the //device as selected 
#include <intrinsics.h>	//Library header file to use __delay_cycles() 

//Macro definition for reversing a bit
#define REVERSEBIT(ADDRESS, BIT)  (ADDRESS ^= (1 << BIT))

//Assuming Default Internal clock of 16.0 MHz
__C_task void main(void)	//Main function 
{
	DDRA = 0x01;	//Set Data Direction Register for PA0 as output
	while(1)		//An infinite looping begins
	{
		REVERSEBIT(PORTA, PA0);
		__delay_cycles(8000000);  //Reverse bit after 0.5 seconds
	}
}