fast PWM mit c

#include <avr/io.h>

#include <avr/interrupt.h>

int main(void){

  DDRB = DDRB | (1<<PB1);

  // Clear OC1A on Compare Match, set OC1A at Bottom

  TCCR1A = TCCR1A | (1<<COM1A1);

  // Fast PWM: TOP = OCR1A

  TCCR1A = TCCR1A | (1<<WGM10) | (1<<WGM11);

  TCCR1B = TCCR1B | (1<<WGM12) | (1<<WGM13);

  // selected clock: prescaler 1024

  TCCR1B = TCCR1B | (1<<CS12) | (1<<CS10);

  // Set TOP = OCR1A

  OCR1A = 0x0000;    //0xFFFF, 0x7FFF auch schon probiert --> immer das gleiche

  // Enable Timer/Counter1 Output Compare match interrupt

  TIMSK = TIMSK | (1<<OCIE1A);

   sei();

   while(1){}

  return 0;

}