/*
 * TIMERwithoutIRQ.c
 *
 * Created: 5.6.2014 15:27:41
 *  Author: maticpi
 */ 
#include <avr/io.h>

void Init();

int main(void)
{
	int cnt=0;
	Init();
	while(1)
	{
		if (TIFR0 & (1<<OCF0A))	//if OCF0A bit is set, the timer has reached 71 (1ms has passed)
		{
			TIFR0 = 1<<OCF0A;	//Write 1 to OCF0A bit to clear it
			cnt++;				//increment counter 
			if (cnt == 100)		//if 1ms has passed for the 100th time, 100ms has passed
			{
				cnt=0;			//reset the ms counter
				PORTB^=0x01;	//and toggle one LED on PORTB
			}
		}
	}
}

void Init()
{
	//IO port
	PORTA=0x08; //0000 1000
	PORTB=0x00; //0000 0000
	PORTC=0x3E; //0011 1110
	PORTD=0x7D; //0111 1101
	//1-output, 0-input
	DDRA=0xF0; //1111 0000
	DDRB=0xFF; //1111 1111
	DDRC=0xC1; //1100 0001
	DDRD=0x82; //1000 0010
	
	//Init timer0
	TCCR0A=(1<<WGM01);	//Output Compare A and B disconnected (normal port operation), Timer mode CTC
	TCCR0B=(1<<CS02);	//Select prescaler 1:256 (18432000/256=72000) 
	OCR0A=71;			//Set top counter value to 71 (0 to 71 equals 72 steps or 1ms at 72kHz timer clock)
}