gistfile1.c

void setup(){
        Serial.begin(115200);
        cli();
        // Enable asynchronous mode for timer2 (uses external 32kHz
        // crystal. This might corrupt the settings registers, so we'll
        // have to (re-)set them all.
        // TCCR2B.
        ASSR |= (1 << AS2);

        delay(10); // Just in case - didn't help :-(

        // Outputs disconnected, normal mode
        TCCR2A = 0;//(1 << WGM21) | (1 << WGM20);

        OCR2B = 60;
        OCR2A = 160;

        // Start timer, prescaler 1024, meaning a single timer increment
        // is 1/32s
        TCCR2B = (1 << CS22) | (1 << CS21) | (1 << CS20);

        // Clear any pending interrupt
        TIFR2 = (1 << TOV2) | (1 << OCF2A) | (1 << OCF2B);
        // enable interrupts
        TIMSK2 = (1 << TOIE2) | (1 << OCIE2A) | (1 << OCIE2B);
        sei();
        while(1);
}

ISR(TIMER2_COMPA_vect) {
        Serial.print("A"); Serial.println(TCNT2);
        // Do nothing, only used to trigger a wakeup
}

ISR(TIMER2_COMPB_vect) {
        Serial.print("B"); Serial.println(TCNT2);
        // Do nothing, only used to trigger a wakeup
}

static volatile bool overflow;
ISR(TIMER2_OVF_vect) {
        Serial.print("O"); Serial.println(TCNT2);
        // Do nothing, only used to trigger a wakeup
}

void loop() {
}