void adcdata ()  {
  uint16_t adc_sum = 0; uint8_t adc_count = 0;
  
  for (adc_count = 0; adc_count < 16; adc_count ++)  {
    ADCINT = 0;
    ADBUSY = 1;
    while (!ADCINT);             // conversion complete ?
    adc_sum += ADC0H;            // build an average
  }adc_sum >>=4;                 // /16 => 8 BIT result
}