[sdiy] MIDI Clock sync advice

Roman Sowa modular at go2.pl
Mon Mar 18 09:42:34 CET 2024



W dniu 2024-03-16 o 10:04, Spiros Makris pisze:
> On Fri, 15 Mar 2024 at 17:47, Roman Sowa via Synth-diy 
> <synth-diy at synth-diy.org <mailto:synth-diy at synth-diy.org>> wrote:
> 
> 
>     If I may just add - maybe it's just my impression, but I think that new
>     generations of programmers educated today have absolutely no idea how
>     microprocessor works.
> 
> 
> That feels true, but we should keep in mind that "programmer" has been a 
> continuously expanding group of people, and you can now be a programmer 
> starting from a wild variety of disciplines, most of which don't start 
> from the bottom, as is customary in electrical engineering and 
> (sometimes) computer science degrees. Most programs I know of have 
> computers and operating systems as a standard class, but 
> microcontrollers and embedded systems as an elective. That is, you can't 
> become an embedded programmer "by accident", unlike python, java and 
> others, which any STEM major will have some knowledge of.

yes, that makes sense. Noone expects the java programmer to know how 
computers work, because java is already created by people who don't know 
that. And I bet the people commercially making websites in WordPress are 
hired as "programmers".
I was thinking rather about programmers writing operating systems like 
Windows

> I suspect Ableton clocks are fairly jittery through USB, so I'll give it 
> another go using a more stable clock and figure out if the ripple is 
> system instability or Ableton acting up.

The USB alone makes 1ms jitter. I was observing MIDI clock out on an 
oscilloscope and no matter what I do, the clock coming out of MOTU 
interface is 1ms jittery AF


> Another approach I intend to try is simply measuring the incoming 
> frequency using a reference timer and then assigning the value 
> (multiplied by a factor) to a second timer to act as a clock.

Well, this is exactly what I described in my previous email.
Maybe you missed it...

  I know it
> will more or less work, but doesn't really have any syncing mechanism; I 

Oh yes it works and does have syncing mechanism. I'd say hard sync if we 
may use analogy to VCO. Pass thru every incoming pulse as MIDI clock and 
reset the timer when then.


> expect the resulting beats will be out of sync.

if incoming clock suddenly increases frequency, you have no chance to 
output enough number of clock before next pulse comes. So I had a wild 
idea to simply add all thoise missing MIDI clocks right away, back to 
back, so the receiving side will not loose any clock.


Roman


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