USB MIDI

egasimus · Joined: Feb 11, 2011 Posts: 113 Location: Bulgaria

I want to implement a USB MIDI controller on an Atmel AVR microcontroller. The USB part is clear - there are numerous software USB stacks for AVRs. However, how should I make it a MIDI device? I could probably patch up a dedicated piece of software to poll the controller and sends MIDI messages over MIDIYoke, but what if I want the controller to appear as a MIDI device? Has someone done this and shared their code?

Also, since this is a percussive controller, when do you suggest that I transmit the Note Off message?

jksuperstar · Posted: Sat Jul 16, 2011 12:09 am Post subject:

For the Note Off, you can do one of the following:

1.) Send no Note off (many percussive sounds don't respond to sustain or release).

2.) Use your own generated Gate time (for example: send Note off 1/16 note after the Note on was sent).

3.) Electrically, just like the threshold for the Note trigger detection, use a similar threshold for Note release. (use this with sounds that respond to a note release). This might work, depending on what type of trigger you're building (piezo, FSR, etc). FSR would be good, piezo might work).

For making a MIDI device, look into USB enumeration. There's a standard set of fields for a deviceto be detected as MIDI. Or, look into this USB stack for Atmel:
http://www.fourwalledcubicle.com/LUFA.php
It already has a MIDI mode, and is detected as a MIDI Device by the host Wink