[sdiy] MIDI Inter-message gap

[Colin f]

> It seems that some synths can't keep up with fast MIDI messages. For
> instance, my Roland JD800 exhibits some odd behaviour if I 
> send sequences at
> it nut-to-butt i.e dropped notes, stuck notes, notes tied 
> etc.  If I insert
> a gap of 250 uS between each message, it works just fine. No unusual
> behaviour. 
> 
> We're seeing some odd results with a Kenton Pro2000 MIDI to 
> CV converter  -
> it sees the MIDI data but doesn't generate voltages. And yet 
> it works fine
> with a Sequentix P3.

The P3 uses a high-priority interrupt to empty the transmit buffer, so the
bytes come out 'nut to butt' (nice expression).
If you are having trouble sending exactly the same data bytes with no gap,
is it possible your MIDI baud rate may be too high ?
That could explain a receiving UART coping with bytes sent with a gap
between them, but not back to back - it might not have time to capture the
leading edge of a follwing start bit as it is still expecting to be in stop
bit of the previous byte.
Or the fall time of the MIDI data line may be too slow ?
I'd compare the two serial output streams on a dual channel scope.

Cheers,
Colin f