nuclear@2: #include <avr/io.h>
nuclear@2: #include <avr/interrupt.h>
nuclear@2: #include <avr/power.h>
nuclear@2: #include "timer.h"
nuclear@2: 
nuclear@2: #define PRESCL_256	4
nuclear@2: /* 256 ticks per interrupt, 256 clock divisor */
nuclear@2: #define TICKS_PER_SEC	(F_CPU / 256 / 256)
nuclear@2: 
nuclear@2: static volatile unsigned long ticks;
nuclear@2: 
nuclear@2: void init_timer(void)
nuclear@2: {
nuclear@2: 	power_timer0_enable();
nuclear@2: 
nuclear@2: 	TCCR0A = 0;
nuclear@2: 	TCCR0B = PRESCL_256;
nuclear@2: 
nuclear@2: 	TIMSK0 |= (1 << TOIE0);	/* enable ovf intr. */
nuclear@2: }
nuclear@2: 
nuclear@2: void reset_timer(void)
nuclear@2: {
nuclear@2: 	ticks = 0;
nuclear@2: }
nuclear@2: 
nuclear@2: unsigned long get_msec(void)
nuclear@2: {
nuclear@2: 	return 1000 * ticks / TICKS_PER_SEC;
nuclear@2: }
nuclear@2: 
nuclear@2: ISR(TIMER0_OVF_vect)
nuclear@2: {
nuclear@2: 	++ticks;
nuclear@2: }