#include <avr/io.h>
#include <avr/interrupt.h>
#include <avr/sleep.h>
void TimerInit();
/*
Frekuensi = 1KHz
prescaller 64 , Xtal 16MHz
tick = 64/16Mhz= 4 us
delay=counter*tick
delay=counter*4 us
counter=delayus/4 us
untuk sampling rate 2 khz maka Tsampling= 1/2Khz= 500 us
counter = 500/4 us = 125
nilai TCNT0= -125 -> karena counter up
*/
ISR (TIMER0_COMPA_vect)
{
  PORTB ^= (1 << PB5);
}
int main(void) {
  DDRB |= _BV(PB5);
  TimerInit(); /// schedule 10ms
  sei();
  /// enable global interupsi
  while (1) {
    sleep_mode(); // sleep
  }
}
void TimerInit(void) {
  // TCNT0 = -250; // reset counter
  TCCR0B = (1 << CS01)|(1 << CS00) ; //prescaller 64
  TIMSK0 |= (1 << OCIE0A); // enable compare match interrupt
  TCCR0A |=_BV(WGM01); //mode Timer CTC
  OCR0A = 125;
}