void startUP() {
    cli();  //Disable Interrupts
    sekunde = minute = sati = timerCounter = 0;

    TIMSK   |= (1<<OCIE0A) | (1<<TOIE0);        //Enable OCIE0A: Timer/Counter0 Output Compare Match A Interrupt Enable

    DDRB    = 0xFF;
    PORTB   = 0x00;
    DDRD    |= (1<<BUFFER0CLK) | (1<<BUFFER1CLK) | (1<<BUFFER2CLK) | (1<<BUFFER3CLK);   //Postavi pinove na kojima su baferi kao izlazne
    PORTD   |= (1<<BUFFER0CLK) | (1<<BUFFER1CLK) | (1<<BUFFER2CLK) | (1<<BUFFER3CLK);   //Stavi logicke 1 na CLK od bafera (podaci se upisuju kad dodje HIGH-to-LOW tranzicija)

    //Postavi sve sedmosegmentne displeje na neku pocetnu vrednost
    SetBufferValue(BUFFER0CLK, SSEG[10]);
    SetBufferValue(BUFFER1CLK, SSEG[5]);
    SetBufferValue(BUFFER2CLK, SSEG[1]);
    SetBufferValue(BUFFER3CLK, SSEG[2]);


    CLKPR = (1<<CLKPCE);    //Ukljuci prescale originalnog takta
    CLKPR |= (1<<CLKPS0); // Divide by 1


    TCCR0A  |= (1 << WGM01);                // Configure Timer 0 for CTC mode
    TCCR0A  |= (1 << CS01) | (1 << CS00);   //Prescaling the timer
    OCR0A   = 0xFA;                         // Set CTC compare value
    TCNT0   = 0x00;                         //Podesi brojac odakle da pocne da broji



    sei();  //Enable Interrupts
}


//Timer0 Interrupt funkcija
ISR(TIMER0_COMPA_vect)
{
    //8MHz, MCU clock Prescale => 1, Timer Prescale => 128, Timer Interrupt every => 4ms
    //TODO:Finish Interrupt timer function
    timerCounter++;
    if(timerCounter >= 250) {
        sekunde++;
        timerCounter = 0;
        PORTD ^= (1<<SECPIN);
    }

    if(sekunde >= 60) {
        minute++;
        sekunde = 0;
    }

    if(minute >= 60) {
        sati++;
        minute = 0;
    }

    if(sati >=24) {
        sati = 0;
    }
}