#include <avr/io.h>
void TimerInit();
unsigned char periode;

  /*
  prescaller 64 , Xtal 16MHz
  tick = 64/16Mhz= 4 us
  delay=counter*tick
  delay=counter*4us
  counter=delayus/4us
  untuk sampling rate 4 khz maka Tsampling= 1/4Khz= 250us
  counter = 250/4us = 63
  nilai TCNT1= -50 -> karena counter up
  */
int main(void) {
    DDRB |= _BV(PB7);
    TimerInit();
    while (1) {
      if (TIFR0&(1<<TOV0)) {
      TCNT0= (unsigned char)-63;
          //clear flag
          TIFR0|=(1<<TOV0);
          PORTB ^= (1 << PB7);
        }
    }
}
void TimerInit(void) {
    TCNT0 = (unsigned char) -63; // reset counter
    TCCR0B = (1 << CS01)|(1<<CS00); //prescaller 8
}