8mhz 1s timer

1stimer.c

    TIMSK1 = (1<<OCIE1A); // output capture enable 
    TCCR1B = (1<<WGM12)|(1<<CS12)|(0<<CS11)|(0<<CS10); //prescaler 256
    OCR1A = 0x7A11; //31.250 * 256 = 8.000.000
    TCNT1 = 0;
    sei();  //system enable interrupt
    
    ISR(TIMER1_COMPA_vect){ 
 i++;
 TCNT1=0;  
}