Serial - MIDI converter (SM = Serial MIDI Converter) is a software solution to get your computer's serial port (or virtual serial port over USB) talking with your MIDI software and hardware.

Normally, to use an Arduino or other micro-controller with your MIDI software you had to build a MIDI-in and MIDI-out circuit with a few parts and an opto-coupler. Easy enough, but then you would typically need a MIDI to USB adaptor to connect it to your computer.

With the SM and a board like you the Arduino with USB, you don't need any other hardware to get your Arduino to play music with software such as Apple's GarageBand or Ableton's Live !

Once the SM is configured it will;
1.Take "MIDI" incoming serial data and forward it to the desired MIDI port.
2.Take MIDI data coming from the chosen MIDI port and forward it out of the serial port.

The license of this software is Freeware, you can free download and free use this audio converter software.