[sdiy] MIDI Inter-message gap

[Scott Gravenhorst]

"David J. Hughes" <hughes_david_j at btopenworld.com> wrote:
>Scott,
>
>on 28/1/08 13:12, Scott Gravenhorst at music.maker at gte.net wrote:
>
>> I'm curious, why is that important?
>
>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.
> 

Hi Dave,

I see, so the synths are otherwise in good working order?  If so, my guess would be that
 a new byte is coming in during critical processing and the interrupt is dropped (crappy
ISR design?), or (God forbid) the MCU implements a soft UART instead of using a hardware
UART <- that sucks because it leaves very little time for processing the message.  Slower
MCU parts of older equipment might add to the problem, but I have no idea what's in those
synths.  The structure of the MCU code could be problematic, but what can you do about
that?...

That sounds like a very annoying problem.


-- ScottG

-------------------------------------------------------------

-- Scott Gravenhorst
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