MIDI Device Implemented with Pepper

Overview

The sequencers in PC using AVR-MIDI are used to control this MIDI interface for SX-150 synthesizer in order to play the existing MIDI files.

Explanation

The project was easy to build due to the use of AVR-MIDI which allows connecting AVR microprocessor directory to USB and USB MIDI profile to be accepted. This signifies that connecting SX-150 to PC will not require other MIDI devices and still the MIDI messages can be handled. The use of AVR-MIDI provides advantage to those without MIDI interface for PC. The MIDI interface is built using pepper and to accept USB MIDI profile, only the firmware is redesigned. For the control tone of SX-150, the CV circuit is used which is a low pass filter that converts PWM from AVR to voltage.

The Pepper-MIDI requires simple firmware since in serial-MIDI, parsing the MIDI messages is a very complex task because of the varying length of messages. On the contrary, the length of these messages are fixed in USB MIDI class which makes even simple parsing. Mac OSX Leopard was used for the development but the Pepper-MIDI will work also in Windows XP without the need for special driver.