so funkts bei mir - zum testen
mfg

Code:

#define OC1A_PIN PB1              // OC1A pin (ATmega8 use PB1)
#define OC1A_DDR DDRB             // OC1A DDR (ATmega8 use DDRB)



int main(void)
{
    uint8_t i = 0;

    // set OC1A pin as output, required for output toggling
    OC1A_DDR |= (1<<OC1A_PIN);
   

    // enable 8 bit PWM, select inverted PWM
   TCCR1A =  (1<<WGM10) | (1<<COM1A1) | (1<<COM1A0);
   
    // timer1 running on 1/8MCU clock with clear timer/counter1 on Compare Match
    // PWM frequency will be MCU clock / 8 / 510, e.g. with 8Mhz Crystal 1960 Hz.
    TCCR1B = (1<<CS11) | (1<<CS10);
 
   
    /*
     *  Dimm LED on and off in interval of 2.5 seconds
     */
    for (;;)
    {   
        /* dimm LED on */
        for (i=0; i<255; i++)
        {
            OCR1AL = i;
         _delay_ms(40); // delay 10 ms
        }
       
        /* dimm LED off */
        for( i=255; i>0; i--)
        {
            OCR1AL = i;
         _delay_ms(40); // delay 10 ms
        }
    }
}