[sdiy] Thoughts on MIDI/DIN to analog sequencer synch

[Grant Richter]

John Blacet makes an excellent MIDI synch chip. I have built up a number of
experimental units using it. I noticed a minor synch issue and I wanted to
post a note for comments.

DIN synch runs at 24 pulses per quarter note (ppq). Let's take the case of
dividing that to 1 pulse per quarter note to run an analog sequencer. We
need to accumulate 24 pulses before the first 1 ppq signal outputs (because
of the divider chain).

I think what you really need are three outputs. The first output is a reset
signal that resets the analog sequencer to the first stage. A second output
triggers the envelope generators for the actual notes. The third output
advances the analog sequencer stages.

The output that triggers the envelopes is ORed with a pulse generated by the
falling edge of the reset line. So when the reset line falls, the first note
is played on the first stage of the analog sequencer. Then 24 ppq latter,
the sequencer is advanced to the second stage and that note is played.

I believe this has more correct musical timing and avoids the delay of
accumulating the first 24 pulses for the output pulse.

Does this seem correct, or am I misunderstanding the way MIDI/DIN synch
works?

Thank you.