[sdiy] bizarre pic-midi issues

[Byron G. Jacquot]

>Hi list, i've stumbled upon some very bizarre PIC MIDI issues. I'm able to send MIDI just fine, but when i try to receive it i half the time get junk and half the time get good data. Usually (for me), the issue seems to be to find the right speed settings, but as the transmission works fine that can't be it. The hardware seems rock solid so i really don't understand what's going on... any hints or thoughts would be awesome! Oh yeah it seems to work "okay" if i use the PIC ONLY to process MIDI, but if i try and do anything else in the same loop i only get garbage - that's on a PIC running at 12MHZ - can't be right. But transmission still works..

How are you getting the data from the UART?  Are you polling or using interrupts?

If you're polling, there's the possibility that the byte you were expecting has been overwritten by another one by the time you go to look for it.

Have you implemented running status and Note On w/ velocity == 0?  Are you handling active sensing and real-time messages?

Have you looked at the incoming data with a scope, to make sure it's got good levels and clean edges?  It could be a signal integrity problem.

Can you verify the content of the MIDI data you're receiving with MIDI Ox or the like?  If the transmitting hardware beyond reproach?

Byron Jacquot