/*
 * Timer.c
 *
 * Created: 28/10/2021 17:51:29
 *  Author: n0x
 */ 

#include <avr/io.h>
#include <avr/interrupt.h>

volatile uint16_t cntr = 0;

void 
Timer_init (void){
	TCCR0A |= (1<<WGM01);		/* Set WGM01 to high to enable CTC mode */
	TCCR0B |= (3<<CS00);		/* Set the clock select bit to pre-scaler 3 
								16MHz / 64 (pre-scaler 3) ==> 250KHz */
	
	TIMSK0 |= (1<<OCIE0A);		/* Set OCIE0A to high to rise an interrupt when the counter matches OCR0A */
	
	OCR0A = 250 - 1;			/* Set the Output Compare Register 0 A to 125 to trigger interrupt every 1ms
								16MHz / 64 (pre-scaler 3) / (250 ) ==> 1KHz (1ms) */
	
	/* 
	For internal 1MHz clock:
	1MHz / 8 (pre-scaler 2) ==> 125 KHz
	1MHz / 8 (pre-scaler 2) / 125 (OCR) ==> 1 KHz (1ms)
	*/
}


uint16_t 
Timer_getTick(void){
	uint16_t tmp;
	cli();
	tmp = cntr;
	sei();
	return tmp;
}


ISR(TIMER0_COMPA_vect){
	cntr++;
}