MIDI Library

MIDI 2.6 and 3.1 and later support all Teensy models.

Hardware Requirements

You can use Serial.print() to observe what your program is doing, while using MIDI, or USB MIDI.

MIDI connects using the UART's transmit and receive pins.

MIDI input requires an optically isolated input. Output requires only 2 resistors. The following schematic is recommended.

When connecting the signals, be sure to connect to the correct pins.

Basic Usage

Initialize the MIDI library. The receive channel may be specified, or MIDI_CHANNEL_OMNI to receive all 16 channels. This only affects reception. You can send on any MIDI channel regardless of this setting.

Transmit basic MIDI messages. These allow you to easily send each MIDI message.

Receive a MIDI message. This returns true if a message has been received, or false if no new message has arrived. After returning true, the get functions can be used to obtain the MIDI message information.

Returns the type of message received. The types are:
       NoteOff
       NoteOn
       AfterTouchPoly
       ControlChange
       ProgramChange
       AfterTouchChannel
       PitchBend
       SystemExclusive

These return the 2 data bytes of the received MIDI message.

Example Output Program

This simple examples sends a rapid sequence of notes. Not very exciting, but a simple and easy test.

#include <MIDI.h>

const int channel = 1;

void setup() {
  MIDI.begin();
}

void loop() {
  int note;
  for (note=10; note <= 127; note++) {
    MIDI.sendNoteOn(note, 100, channel);
    delay(200);
    MIDI.sendNoteOff(note, 100, channel);
  }
  delay(2000);
}

Example Input Program

/* MIDI Input Test - for use with Teensy or boards where Serial is separate from MIDI
 * As MIDI messages arrive, they are printed to the Arduino Serial Monitor.
 *
 * Where MIDI is on "Serial", eg Arduino Duemilanove or Arduino Uno, this does not work!
 *
 * This example code is released into the public domain.
 */
 
#include <MIDI.h>

void setup() {
  MIDI.begin(MIDI_CHANNEL_OMNI);
  Serial.begin(57600);
  Serial.println("MIDI Input Test");
}

unsigned long t=0;

void loop() {
  int type, note, velocity, channel, d1, d2;
  if (MIDI.read()) {                    // Is there a MIDI message incoming ?
    byte type = MIDI.getType();
    switch (type) {
      case NoteOn:
        note = MIDI.getData1();
        velocity = MIDI.getData2();
        channel = MIDI.getChannel();
        if (velocity > 0) {
          Serial.println(String("Note On:  ch=") + channel + ", note=" + note + ", velocity=" + velocity);
        } else {
          Serial.println(String("Note Off: ch=") + channel + ", note=" + note);
        }
        break;
      case NoteOff:
        note = MIDI.getData1();
        velocity = MIDI.getData2();
        channel = MIDI.getChannel();
        Serial.println(String("Note Off: ch=") + channel + ", note=" + note + ", velocity=" + velocity);
        break;
      default:
        d1 = MIDI.getData1();
        d2 = MIDI.getData2();
        Serial.println(String("Message, type=") + type + ", data = " + d1 + " " + d2);
    }
    t = millis();
  }
  if (millis() - t > 10000) {
    t += 10000;
    Serial.println("(inactivity)");
  }
}

Details