Receive BLE MIDI events on Puck.js and other Espruino devices

puck-js-midi-receiver.js

/// Receives MIDI events
function recv(evt) {
  var data = evt.data;
  var cmd = data[2] & 0xF0; // command
  var chn = data[2] & 0x0F; // channel
  var num = data[3]; // note or controller number
  var val = data[4]; // velocity or controller value
  switch(cmd) {
    case 0x80: // noteOff
    case 0x90: // noteOn
      if (val) LED1.set(); else LED1.reset();
      break;
    case 0xB0: // CC
      if (val) LED2.set(); else LED2.reset();
      break;
    default:
      if (val) LED3.set(); else LED3.reset();
  }
}

/// Turns the device into a MIDI controller
function init(name) {
  NRF.setServices({
    "03B80E5A-EDE8-4B33-A751-6CE34EC4C700": { // MIDI
      "7772E5DB-3868-4112-A1A9-F2669D106BF3": {
        readable: true,
        writable: true,
        notify: true,
        value: [0x80, 0x80, 0x00, 0x00, 0x00],
        onWrite: recv
      }
    }
  });
  NRF.setAdvertising([
    // Flags: LE Limited Discoverable Mode, BR/EDR Not Supported
    0x02, 0x01, 0x05,
    // Complete Local Name: PuckCC
    0x07, 0x09,
    name.charCodeAt(0),
    name.charCodeAt(1),
    name.charCodeAt(2),
    name.charCodeAt(3),
    name.charCodeAt(4),
    name.charCodeAt(5),
    // MIDI
    0x11, 0x06, 0x00, 0xC7, 0xC4, 0x4E, 0xE3, 0x6C, 0x51,
    0xA7, 0x33, 0x4B, 0xE8, 0xED, 0x5A, 0x0E, 0xB8, 0x03
  ]);
}

init("PuckCC");