Timer Counter zu schnell?

#define F_CPU 16000000      //Frequency = 16 MHz

#include <avr/io.h>

#include <util/delay.h>

#include <avr/interrupt.h>

//volatile uint8_t keystate = 0;        

int main(void)

{

  TCNT0 = 0x00;    // Timer counter mit 0 initialisieren

  OCR0 = 0x00;    // beim ersten overflow interrupt

  TIMSK |= (1<<OCIE0);    // Timer compare enabled

  DDRA = 0x00;        // Port A Input

  DDRB = 0xFF;        // Port B Output

  DDRC = 0xFF;        // Port C Output

  PORTA = 0xFF;        // Pullups an A an

  sei();

  TCCR0 = ((1<<WGM01) | (1<<COM00) | (1<<CS02)|(1<<CS00));    // Toggle Mode on , Prescaler 1024

    while(1)

    {

    }

  return 1;

}

ISR (TIMER0_COMP_vect)

{

  PORTC^=0X0F;  // Toggle Port C

}