Use an Arduino Uno microcontroller and the Olimex SHIELD-MIDI shield to filter MIDI events.
- Write your own config.ino file to react to MIDI messages in appropriate handlers (e.g., onProgramChange, onControlChange, onNoteOn, etc.).
- Use the MIDI interface described into midi.h to send MIDI mesages
The given config.ino file is configured to interconnect a Roland FR-1xb with a Roland E-A7 keyboard arranger. See http://www.haskus.org/arduino/midi