[sdiy] DIY MIDI clock to sync pulses

[m.bareille at free.fr]

Hi Louis,

> It's not a problem of it not keeping sync, it's not outputting pulses at
> all!  By the way, I'm not trying to do DIN sync here.  I merely need a
> clock pulse for my modular that runs at the same speed as midi clock.

That's what the MC628 is supposed to do... when it work ;)

>
> Anyway, I thought Bareille might've made a mistake and put up the wrong
> HEX code on his page, but his code won't compile in MPASM either,

No and no :) There is no mistake in the code. It can be improved to get a more
powerful  midi clock, but it work fine like this anyway and with a very correct
sync accuracy for a midi thing of this level...

Just before i write this email , i have downloaded the MC628 source and compiled
it with the last  MASM version without any troubles... You can ignore compiler
's warning messages code 302 else check your MASM compiler!

>As Bareille specifies a non-existant 8-pin 4N28
>I have also tried some true 8-pin optocouplers, just to see if
>the output signal might be slightly different, but no luck.

I do not specify anything for the opto :) You can use any "MIDI compatible" ones
4n28 is not non-existant :) may be a little bit obsolete nowoday ?
No problem to replace it by something better like the classic 6N137/138 if you
prefear. Please be sure your MIDI wires are not reversed. If your opto is dead,
the Midi clock wont pulse too...


Other things:

- When you power  up the Midi clock for the first time or just after burning the
PI you should download a complete parameters setup using sysex or the PC config
software...

- the pulse signal generated by the MIDI clock can be very short , may be too
much...so if you have a led connected to the pulse output with a resistor, you
will probably see nothing happen... Use a scope to check the output signal...
You can increase the pulse length by changing the "time" value in
the code as follow :

Pause		movlw	12
		movwf	TEMP1

replace '12' by a bigger value ( 1<x<255 ) ...Bigger is this value longuer is
the generated pulse but lower the max tempo limit the Midi clock can receive..

Well i hope this will help you , good luck :)

Cheers,

Marc B.

PAPAREIL SYNTH LABS
http://m.bareille.free.fr