Arduino is an open-source physical computing platform based on
a simple Input/Output board and a development environment that implements
the Processing/Wiring language, which is similar to C programming.
Arduino can be used to develop stand-alone interactive
objects or can be connected to software on your computer (e.g.MIDI,
Flash, Processing, MaxMSP). The open-source IDE can be downloaded
for free (currently for Mac OS X, Windows, and Linux).
MIDI USB Driver Installation
Operate MIDI IN/OUT on the Miduino, via the USB cable, using MIDI
to USB drivers or the UNO or MEGA2560 can have Class
Compliant USB/MIDI firmware.