[sdiy] CVin-MIDIout idea

[RMC]

Hello

My friend Laurent and I have an aspiration which I am working on. I expect 
there are pitfalls that I haven't spotted so I would appreciate some expert 
input.

The aims:
(1)to generate a MIDI clock along with start/stop/(continue) words, which is 
driven from an analogue clock input - a square wave from a voltage 
controlled LFO.
(2) To generate start/stop/(continue) trigger outputs, and a clock output, 
as a result of MIDI data input.

These two sites give some useful insights into how to go about it:
http://tomscarff.tripod.com/ - general MIDI interfacing using Microchip PICs
http://www.maxmidi.com/diy/metro/index.html - MIDI metronome that does part 
(2) of what I want

The reason:
to be able to drive a MIDI/CV sequencer (my Doepfer MAQ16/3 for example) 
from an analogue sequencer (my Korg SQ-10 for example) or other analogue 
CV-orientated equipment.  The analogue kit would provide a trigger pulse 
that gets converted to 0xFA (start), another one which gets converted to 
0xFC (stop), and of course the LFO input generating the 0xF8 clock stream.

The plan:
Use a VCLFO running at speeds of upto (say) 80 Hz. A clock frequency of 40Hz 
along with the 24ppqn MIDI clock rate means that 40Hz equates to 100bpm.

A PIC will be used to divide this LFO down (binary fixed/2/4/8/16 and decade 
selectable 1--10) to generate other outputs, which can be used within the 
system for modulation etc., running other sequencers.

The same PIC or another PIC , possibly along the lines of Tom Wiltshire's 
recent and stimulating VCLFO PIC project, or  a VCLFO implemented in 
hardware, means that the MIDI sequencer can have its speed modulated by CVs. 
This is what I like about my SQ-10 - you can take the C channel CV output 
back into the VC clock input in order to speed the sequence up and down and 
hence generate interesting rhythms. Or use EGs to control the rate. Or 
keyboard CV. Lots of experimentation available, in other words!

I am learning (slowly) to program in assembler so that I can generate the 
MIDI words, and also so that I can edit the assembler as per the Metronome 
URL.

The plan is to end up with a 10HP width eurocard module which has a MIDI in 
and MIDI out, and has clock ins and outs and so on.

Assuming that I can write the code to generate F8, FA and FC and FB 
("continue") which are probably best being IRQ driven, is there anything 
obvious that would prevent the plan from actually being able to control a 
MIDI sequencer such as the Doepfer?

Thanks for any advice or observations

RMC, England