[sdiy] Din Sync Master Implementation

[maxrest at gmx.de]

It was behind the master and doesn't accumulate for sure. 

If it is in sync, I can start, stop and continue it for minutes without any
problems. If it's not, it stays with the same shift. I checked the
signals and signals' count & timing with the logic analyzer, it looks
like intended and described.

What I observed: when I press STOP on the 909, the next start from my
master get's the machine in sync.

I found out about the 909 sequencer lag bug [1] but the machine I test 
here is already updated. Does anyone know if they only fixed MIDI 
synchronisation with it?

Best,

Max


[1] http://www.diprec.com/tr909/tr909.htm

> Does the 909 fall behind the master or get ahead? After multiple cycles of your test sequence is the error cumulative. I.e. Does it fall progressively further behind if you keep repeating the test? Might help diagnose what's going on. 
>
> -Richie,
>
> Sent from my Xperia SP on O2
>
> ---- maxrest at gmx.de wrote ----
>
>> Hello fellows,
>>
>>
>> at first I'd like to introduce myself: My name is Max and I run a small
>> company called E-RM in Berlin. We make clock generators and other audio
>> related custom projects.
>>
>> I recently came across the task to implement a (Roland) DIN Sync master
>> in a microcontroller and found an old thread in the archives [1]
>> describing some details.
>>
>> My implementation uses asymetrical clock ticks with a positive pulse
>> width of 5ms. There are three knobs to controll the transport, PLAY,
>> STOP/PAUSE and CONTINUE
>>
>>
>> Let's assume we are at the beginning and everything is stopped:
>>
>> Start: Low, no clock Ticks
>>
>> -> press PLAY
>>
>> Start: Low>High -> 10-60ms delay -> Ticks start
>>
>> -> press STOP/PAUSE
>>
>> Start: High, no clock ticks
>>
>> -> press CONTINUE
>>
>> Start: High, Ticks continue
>>
>> -> press STOP/PAUSE
>>
>> Start: High, no clock ticks
>>
>> -> press PLAY
>>
>> Start: High>Low -> 10-60ms delay -> Start: Low>High -> 10-60ms delay ->
>> Ticks start
>>
>>
>>
>> I tested my code with a Roland 606, 707 and 909. 606 and 707 work
>> pefectly fine with that scheme.
>>
>> The 909 doesn't. Every now and then it is shifted by one clock cycle. I
>> do not understand this behaviour as everything I read implies that I
>> have to wait _at least_ 9ms from the rising edge on the Start signal
>> till my first tick. Otherwise it may get lost in CPU preperation time.
>>
>> What does it mean that the 909 doesn't like longer wait times? Does
>> anyone have a clue on this?
>>
>>
>> Best,
>>
>> Max
>>
>>
>> [1] http://dropmix.xs4all.nl/pipermail/synth-diy/2011-May/032373.html
>>
>>
>>
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