[sdiy] MIDI control syntax to debug 16 bits values on the MIDI steam using MIDI-OX MIDI monitor ?

[Jay Schwichtenberg]

Most real digital oscilloscopes these days have asynchronous serial 
decoding built into them.  This is what MIDI uses at 31250 bits per 
second with 8 data bits, 1 stop bit and no parity. You attach the scope 
between the serial port transmitter and driver or/and receiver (opto) 
and the serial port receive. This will show you the data bytes as they 
go buy. Usually you have choices of binary, decimal, hex and ASCII for 
the data decode.

For USB MIDI there are USB debug tools you can see what's going across 
the wire. Usually it's easier to debug with software but if you don't 
have access to the software you can't do much other than a HW debugger.

Jay S.

On 1/11/2025 6:53 PM, chris wrote:
> Apart from what has been said about MIDI never being able to transport
> full 8 bit bytes directly, there is one thing to have in mind with a
> MidiOx monitor.
>
> When receiving just data bytes (hi bit of 0), the receiving MIDI driver
> applies running status, and in turn you see expanded full messages in
> MidiOx even though there wasn't a status byte on the cable.
>
> I just experienced this last month debugging a wonky sender. Using an
> oscilloscope on the cable (well, after the opto coupler...) revealed
> what was really transferred physically.
>
> Chris
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