Structure

”MEMIDION" is MIDI instruments that you can play with DAW software or MIDI controllers.

MEMIDION is a slide whistle that controlled by the micro-controller. The motor with the caterpillar slides the slide whistle. The slide amount is controlled by ToF range finder sensor VL6180. 

MEMIDION Body

Motor (Caterpillar) control via motor driver DRV 8835 at Arduino.

Measure the distance of the tip of the slider of the whistle with the distance sensor VL6180X to control the slide amount.

Arduino USB-MIDI device conversion

Write Moco for LUFA firmware to Arduino and let Arduino recognize it as a MIDI device. 

The detail is right below.

  https://github.com/kuwatay/mocolufa

Setting of DAW software Reason

Anything is OK if DAW can output MIDI, but we will use Reason this time.

Place the external MIDI instrument and select "MocoLUFA" for the device.

Arduino IDE Code

Move the slider of the whistle with the MIDI signal from the MIDI keyboard or DAW and change the scale. The slide amount is controlled by the measurement value of distance sensor VL6180X.

I used the following as a MIDI library for Arduino.

https://github.com/FortySevenEffects/arduino_midi_library/

The library for distance sensor VL6180X is below.

https://github.com/pololu/vl6180x-arduino

#include <MIDI.h>           
MIDI_CREATE_DEFAULT_INSTANCE();
#include <Wire.h>
#include <VL6180X.h>

uint8_t Note, NoteOld;
VL6180X sensor;

int meas;
int aim = 50;
int diff = 5;
int moveTime = 100;

void setup() {
  Wire.begin();
  MIDI.begin();
  pinMode(2, OUTPUT);
  pinMode(3, OUTPUT);

  sensor.init();
  sensor.configureDefault();
  sensor.setTimeout(500);
}

void loop() {
 //MIDI detection 
 if (MIDI.read()) {
    switch(MIDI.getType()) {
      case midi::NoteOn:
        digitalWrite(2, HIGH);
        digitalWrite(3, LOW);
        delay(10);
        digitalWrite(2, LOW);
        digitalWrite(3, LOW);
        Note = MIDI.getData1();    // Note = 48-72 ALESIS Q25
     break;

     case midi::NoteOff:
        Note = 255;
     break;
   }
 }

  //Slide distance setting
  if(Note == 57) aim = 22;  //A
  if(Note == 58) aim = 33;  //A#
  if(Note == 59) aim = 41;  //B
  if(Note == 60) aim = 52;  //C
  if(Note == 61) aim = 62;  //C#
  if(Note == 62) aim = 71;  //D
  if(Note == 63) aim = 81;  //D#
  if(Note == 64) aim = 90;  //E
  if(Note == 65) aim = 97; //F
  if(Note == 66) aim = 103; //F#
  if(Note == 67) aim = 109; //G
  if(Note == 68) aim = 116; //G#
  if(Note == 69) aim = 121; //A
  if(Note == 70) aim = 126; //A#
  if(Note == 71) aim = 129; //B
  if(Note == 72) aim = 133; //C

  //Distance sensor measurement
  meas = sensor.readRangeSingleMillimeters();

  //Motor operation
  if(meas > (aim - diff) && meas <  (aim + diff)){
    digitalWrite(2, LOW);
    digitalWrite(3, LOW);
  }else if(meas > aim){
    digitalWrite(2, LOW);
    digitalWrite(3, HIGH);
  }else if(meas < aim){
    digitalWrite(2, HIGH);
    digitalWrite(3, LOW);
  }
}

Operation

The amount of slide will change with the MIDI keyboard. 

Automatic performance as MIDI sound source with DAW is also possible. My breath has to keep blowing....