   pinMode(SWITCH_A_DN, INPUT_PULLUP);
   pinMode(SWITCH_B_UP, INPUT_PULLUP);
   pinMode(SWITCH_B_DN, INPUT_PULLUP);
-  delay(1000);
+  delay(500);
   load_calibration();
 }
 

}

void output_notes() {
  uint8_t number;
  for (int i = 0; i < BUTTON_COUNT; i++) {
    if (notes[i].volume > 0) {
      number = 60 + tune + i;
      if (number != notes[i].number) silence_note(i); 
      if (! notes[i].playing) {
        notes[i].number = number;
        usbMIDI.sendNoteOn(notes[i].number, notes[i].volume, MIDI_CHANNEL);
        log_event(" on", notes[i].number, notes[i].volume);
        notes[i].playing = 1;
      }
      if (notes[i].volume != notes[i].last_volume) {
        usbMIDI.sendPolyPressure(notes[i].number, notes[i].volume, MIDI_CHANNEL);
        log_event(" pp", notes[i].number, notes[i].volume);
      }

#define BUTTON_COUNT 20
// MIDI params
#define MIDI_CHANNEL 1
#define ROOT_NOTE 48
// uncomment to enable serial debugging
// #define SERIAL_DEBUG 1

