Microcontrollers and Apple MIDI

My Arduino MIDI Library is using Arduino Streams as a basic design feature and therefore it supports Bluetooth, TCP/IP and UDP.

I am usually programming on an old Macbook, so I was wondering if I can extend my library to support Apple MIDI as well.

After some research I found that Apple MIDI communicates on 2 UDP ports: one for the session management and the other for the midi data. I wanted to avoid me having to implement the protocol myself and found the C implementation from Thorsten Klose which provides a quite nice abstraction layer: All I needed to do was to implemeent my C++ class which provides the necessary callback methods and integrates into my MIDI parser.

Arduino Sketch

Here is the example sketch which uses the new functionality:

#include <WiFi.h>
#include "Midi.h"

MidiCallbackAction action;
AppleMidiServer apple(&action);

const char *SSID = "your ssid";
const char *PWD = "your password";

void onNoteOn(uint8_t channel, uint8_t note, uint8_t velocity) {
  Serial.print("onNoteOn: ");
  Serial.println(note);
}

void onNoteOff(uint8_t channel, uint8_t note, uint8_t velocity) {
  Serial.print("onNoteOff: ");
  Serial.println(note);
}

void setupWIFI() {
  Serial.begin(119200);
  MidiLogLevel = MidiInfo;

  WiFi.begin(SSID, PWD);
  while (WiFi.status() != WL_CONNECTED) {
    Serial.print('.');
    delay(1000);
  }

  Serial.print("Connected to IP address: ");
  Serial.println(WiFi.localIP());
}

void setup() {
  action.setCallbacks(onNoteOn, onNoteOff);
  setupWIFI();
  apple.begin(5004);
}

void loop() {
  if (!apple.loop()){
    delay(10);
  }
}

As you can see, by using the AppleMidiServer class we use the same concepts that we already know from in all other examples and because this is a server class, we can not only receive MIDI messages, but also produce them.

Dependencies

• arduino-midi

OS/X MIDI Setup

• Connect your MIDI keyboard to the computer.
• Open the Audio Midi Setup tool.
• Goto Window Show MIDI Studio.
• Double click on Network
• The entry ‘AppleMidi’ should be available in the Directory
• Select it and click on the button
• In the Live Routings select your Keyboard on the line with ->

If you hit the keys, you should see the corresponding entries in the Arduino Serial Monitor