tiny45 ADC3 immer Null

void temp_init(void)

{

  DIDR0 = (1<<ADC3D);          // disable digital

  ADCSRA = (1<<ADEN) 

      | (1<<ADPS2) | (1<<ADPS1) | (1<<ADPS0);

  ADMUX = 3;            // select pin, Vcc as reference

  ADCSRA |= (ADSC);          // start conversion

  while (ADCSRA & (1<<ADSC) );    // wait until completed

  int16_t discard = ADC;        // 10 bit value

}

int16_t temp_get(void) 

{

  ADCSRA |= (ADSC);          // start conversion

  while (ADCSRA & (1<<ADSC) );    // wait until completed

  return (ADC);            // 10 bit value

}

.......

while(1)

  {

    _delay_ms( 500 );

    tmp = temp_get();

    itoa(tmp, buffer, 10);

    LCD_WriteString(8, 3, buffer);

...............