         break;
       case 'a':
         setting = SET_AMPLITUDE;
+        break;
+      case 'm':
+        setting = SET_ADC_HALF;
         break;
       case 'o':
         dds.on();

}

ISR(ADC_vect) {
  TIFR1 = _BV(ICF1);
  PORTD |= _BV(2);
  dds.clockTick();
  PORTD &= ~_BV(2);
}

        dds.start();
        Serial.println(F("RefClk - 100 = "));
        Serial.println(dds.getReferenceClock());
        Serial.println("> ");
        break;
      case 'l':
        Serial.println(F("Start frequency listening, DDS off"));
        dds.off();
        listening = true;
        lastOutput = millis();
        Serial.println("> ");
        break;
      case 'L':
        Serial.println(F("Stop frequency listening, DDS on"));
        listening = false;
        samples = 0;
        dds.on();
        Serial.println("> ");
        break;
      case 'T':
