Arduino and GarageBand

Serial - MIDI converter

SM is software that connects your computer’s serial port with MIDI software and hardware.

Normally, to use an Arduino or other micro-controller with your MIDI software you had to build a MIDI circuit with a MIDI controller.

With SM and a USB enabled Arduino with USB, you can play music with software such as Apple’s GarageBand or Ableton’s Live.

SM takes incoming serial data and sends it to the desired MIDI port. It also takes MIDI data coming from the chosen MIDI port and forwards it to the serial port.

SM conversion.png

Testing it out

Download SM and unzip it
Download and install themidibus library in the documents:processing:libraries folder
Open Apple's Audio MIDI Setup
Select Window>Show MIDI Window
Double click on the IAC Driver
Enable Device is Online
You can close Audio MIDI Setup
Open Arduino 1.0 or greater.

Upload the following program:

//  *****************************************************************************************************************
//  *                                                                                                               *
//  *                                         SpikenzieLabs.com                                                     *
//  *                                                                                                               *
//  *                                   Very Simple Serial to MIDI DEMO                                             *
//  *                                                                                                               *
//  *****************************************************************************************************************
//
// BY: MARK DEMERS 
// May 2009
// VERSION: 0.1
//
// DESCRIPTION:
// Demo sketch to play notes from middle C in the 4th octave up to B in the 5th octave and then back down.
//
//
// HOOK-UP:
// 1. Plug USB cable from Arduino into your computer.
//  
//
// USAGE:
// 1. Install and Set-up Serial MIDI Converter from SpikenzieLabs
// 2. Open, compile, and upload this sketch into your Arduino.
// 3. Run Serial MIDI Converter in the background.
// 4. Launch your music software such as Garage Band or Ableton Live, choose a software instrument and listen to the music.
//
//
// LEGAL:
// This code is provided as is. No guaranties or warranties are given in any form. It is up to you to determine
// this codes suitability for your application.
//

int note = 0;     

void setup() 
{
  Serial.begin(57600);                                       // Default speed of the Serial to MIDI Converter serial port
}

void loop() {

  for(int note=60; note<=83; note++)                        // Going Up
  {
    MIDI_TX(144,note,127);                                  // NOTE ON
    delay(100);

    MIDI_TX(128,note,127);                                  // NOTE OFF
    delay(100);
  }

  for(int note=82; note>=61; note--)                       // Coming Down
  {
    MIDI_TX(144,note,127);                                  // NOTE ON
    delay(250);

    MIDI_TX(128,note,127);                                  // NOTE OFF
    delay(250);
  }

}


void MIDI_TX(unsigned char MESSAGE, unsigned char PITCH, unsigned char VELOCITY) {
  Serial.write(MESSAGE);
  Serial.write(PITCH);
  Serial.write(VELOCITY);
}

Launch SM by navigating to application.macosx>source>Serial_MIDI_Converter_V2D.pde When you open it, you will be prompted to create a folder. Do that. Then rin the sketch
Choose the serial port that the Arduino is using

This is the serial port that will be used for both serial TX and RX. Your micro-controllers serial port must be set to 57600 bps 8N1. (Even though MIDI is transmitted at 31250 bps, the serial port is set at a faster baud rate to help minimize any lag time.)
Select 57600
Choose a MIDI-in port.
This is the source of MIDI data that will be sent out of the serial port. This can be a little confusing, if you are using audio software this will be the MIDI-out of the software ! If you are using an external controller like a keyboard, this will be the MIDI-in port from that device.
Choose a MIDI-out port.
When the SM receives serial data it will pass the data out of this MIDI port. You will most often choose the port that your audio software uses as input, but you could also choose another MIDI device.
The SM must be running to direct MIDI to and from serial ports. So, just let it run in the background.
Open GarageBand
Select Piano
Navigate to Preferences and open MIDI/Audio.
Select System Setting
Edit Piano and select Digital Basic
Close and reopen GarageBand
Hear the notes!