This is a MIDI interface for SX-150 to control it with sequencers in PC using AVR-MIDI.It is very easy to build such device with it. AVR-MIDI allows us to connect AVR microprocessor directory to USB and to accept USB MIDI profile. Which means no other MIDI devices are required to connect SX-150 to PC, and still have capability to handle MIDI messages. If you don’t have a MIDI interface for PC, AVR-MIDI has advantage.