#include <avr/io.h>
void TimerInit();
unsigned char periode;
/*
 prescaller 8 , Xtal 16MHz
 tick = 8/16Mhz= 0.5 us
 delay=counter*tick
 delay=counter*1/2us
 untuk sampling rate 40 khz maka Tsampling= 1/40Khz= 25us
 counter = 25/0.5us = 50
 */
int main(void) {
      DDRB |= _BV(PB7);
      TimerInit();


      while (1) {
            if(TIFR0&(1<<OCF0A)){
                PORTB ^= (1 << PB7);
                TIFR0 |= (1<<OCF0A);
                }
          }
      }
void TimerInit(void) {
    TCCR0B  = (1 << CS01) ; //prescaller 8
    TCCR0A |=_BV(WGM01); //mode Timer CTC
    OCR0A =  50;
  }