/*
 * Analog Comparator Test
 */
volatile bool intFlag = false;

void setup()
{
  Serial.begin(9600);
  Serial.println(F("*** Analog Comparator Test ***"));
  Serial.println();
  //DIDR1 |= bit(AIN1D) | bit(AIN0D);
  //ADCSRB |= bit(ACME);
  //ADCSRA &= ~bit(ADEN);
  //ADMUX |= bit(MUX0);
  ACSR = bit(ACI) | bit(ACIE);
  //bitSet(DDRB, 5);
  //bitWrite(PORTB, 5, bitRead(ACSR, ACO));
}

void loop()
{
  if (intFlag){
    Serial.println("ACO: " + String(bitRead(ACSR, ACO)));
    Serial.println();
    intFlag = false;
  }
}

ISR(ANALOG_COMP_vect)
{
  if (!intFlag) intFlag = true;
}