ADCSRA = _BV(ADEN) | _BV(ADATE) | _BV(ADPS1) | _BV(ADPS0);
ADMUX = _BV(REFS1) | _BV(MUX0);
// ADCSRB = _BV(REFS2);
DIDR0 = _BV(ADC1D) | _BV(AREFD);
ADCSRA = _BV(ADEN) | _BV(ADATE) | _BV(ADPS1) | _BV(ADPS0);
ADMUX = _BV(REFS1) | _BV(MUX0);
// ADCSRB = _BV(REFS2);
DIDR0 = _BV(ADC1D) | _BV(AREFD);