Set up AVR timer interrupt

/* initialize timer interrupt */
void init_isr_timers() {
    /* OC1A/OC1B disconnected */
    TCCR1A = 0;
    /* CTC mode, top in OCR1A / Timer clock = CLK/1024 */
    TCCR1B = (1<<WGM12)|(1<<CS12)|(1<<CS10);
    /* set OCR1A top value for 20Hz (10 periods in one second) */
    /*   0x0168 for CPU @ 7.3728MHz */
    OCR1A = 0x0168;
    /* enable Timer/Counter 1 interrupt */
    TIMSK = (1<<OCIE1A);
}

/* timer/counter 1 interrupt handler */
ISR(TIMER1_COMPA_vect) {
    /* Ohhh, lovely! :) */
}

int main() {
    /* initialize timer interrupt */
    init_isr_timers();
    /* enable interrupts */
    sei();

    /* main loop */
    for(;;) {}
}