Making Music With MIDI


The term music is being used in its loosest sense for this project. An ultrasonic range finder is used to select notes to play through a MIDI cable.

You Will Need

  • 1 x 220 Ohm Resistor
  • 1 x MIDI Jack
  • 1x SRF05 Ultrasound Sensor
  • Jumper Wires
  • USB MIDI Adapter

Making The Circuit

Arduino Circuit

Programming The Arduino

Buried in among this code are the details for using the ultrasound sensor. The value obtained from this is converted into a value for a MIDI note.

You will also see how you can go about changing the instrument being used.

#define ECHOPIN 2
#define TRIGPIN 3

int lastnote=0;

void setup() {
  pinMode(ECHOPIN, INPUT);
  // chooses the synth voice
  programChange(0xc0, 0x36);

void loop() {
  digitalWrite(TRIGPIN, LOW);
  digitalWrite(TRIGPIN, HIGH);
  digitalWrite(TRIGPIN, LOW);
  int distance = pulseIn(ECHOPIN, HIGH);
  distance= distance/58;
  distance = constrain(distance,10,100);
  distance = map(distance,10,100,90,60);
  if (distance!=lastnote)
    noteOn(0x90, lastnote, 0x00);
    noteOn(0x90, distance, 0x45);
    lastnote = distance;

void noteOn(int cmd, int pitch, int velocity) {

void programChange(int cmd, int data1) {


Clearly, this sounds pretty dreadful. The trick to making this kind of thing work is to consider how the values obtained from the sensor (or any input you choose to replace it with) are converted into notes. Get this right and you have something a little more interesting.