ttyMIDI is a GPL-licensed program that allows external serial devices to interface with JACK MIDI clients. COMPILATION The ttyMIDI source code is comprised of a single C file. To compile it, just run the following command: make This program depends on JACK, so you should have the development headers for that installed. In Debian or Ubuntu, you can install it by running: apt-get install libjack-jackd2-dev After you compile ttyMIDI, you may wish to copy it to /usr/bin for easy access. This can be done simply by following command: sudo make install USAGE First, you need an external device that can send MIDI commands through the serial port. To find out more about programming an external device, read the TTYMIDI SPECIFICATION section. If you are using an Arduino board (http://www.arduino.cc), read the instructions under the arduino folder. Once your device is programmed and connected to your PC's serial port, follow the instructions below. To connect to ttyS0 at 2400bps: ttymidi -s /dev/ttyS0 -b 2400 To connect to ttyUSB port at default speed (115200bps) and display information about incoming MIDI events: ttymidi -s /dev/ttyUSB0 -v ttyMIDI also creates a JACK MIDI input port that feeds incoming MIDI events back to the serial port. If you would like to use a GUI to connect your MIDI clients, there are many available. One of my favorites is qjackctl. TTYMIDI SPECIFICATION The message format expected by ttyMIDI is based on what I could gather about the MIDI specification online. I tried to make it as similar as possible to the specification, but some differences exist. The good news is that as long as you follow the specification described below, everything should work. Every MIDI command is sent through the serial port as 3 bytes. The first byte contains the command type and channel. After that, 2 parameter bytes are transmitted. To simplify the decoding process, ttyMIDI does not support "running status", and it also forces every command into 3 bytes. So even commands which only have 1 parameter must transmit byte #3 (transmitting a 0 in this case). This is described in more details in the table below: byte1 byte2 byte3 Command name 0x80-0x8F Key # (0-127) Off Velocity (0-127) Note OFF 0x90-0x90 Key # (0-127) On Velocity (0-127) Note ON 0xA0-0xA0 Key # (0-127) Pressure (0-127) Poly Key Pressure 0xB0-0xB0 Control # (0-127) Control Value (0-127) Control Change 0xC0-0xC0 Program # (0-127) Not Used (send 0) Program Change 0xD0-0xD0 Pressure Value (0-127) Not Used (send 0) Mono Key Pressure (Channel Pressure) 0xE0-0xE0 Range LSB (0-127) Range MSB (0-127) Pitch Bend Not implemented: 0xF0-0xF0 Manufacturer's ID Model ID System Byte #1 is given as COMMAND + CHANNEL. So, for example, 0xE3 is the Pitch Bend command (0xE0) for channel 4 (0x03).