[sdiy] midi clock

[Gavin]

well, these hardware midi threads have also prompted me to ask a question
I've had under my belt for a while.  Has anybody seen or done any work on
providing Midi capability for old casio's? particularly the "MT" series. 
I've seen the SK-1 Midi article, but it doesn't really apply and also
requires a custom chip circa '88 that I don't think is available.  The
relevant processes for Midi to control are 1. the keyboard and 2. The Tempo
of the presets and rhythms 3. which sounds and rhythms are chosen.  I've
logged a HUGE amount of hours analyzing the ins and outs on the big NEC uP
on these guys and could probably build a clone uP that would run off an
external clock etc.  but I would really much rather build a hardware Midi
interface and leave the uP alone.  So if anyone's done or seen anything like
this, please pass it on!  It's a pet project that's been on the back burner
for way too long.
Thanks
G.
----------
>From: Seb Francis <seb at is-uk.com>
>To: pfperry at melbpc.org.au
>Cc: synth-diy at dropmix.xs4all.nl
>Subject: Re: [sdiy] midi clock
>Date: Tue, Dec 3, 2002, 7:44 PM
>

>pfperry at melbpc.org.au wrote:
>
>> > > detecting any given MIDI byte. Both use a UART chip (6402) which seems
>> > > to simplify things considerably.
>> >
>> Well as a non-programmer I am naturally sympathetic to the 6402, but 
>unless you salvage one from a very old modem or compter, a PIC costs 
>less... also, some of  those Penfold circuits might be making heroic 
>assumptions regarding the MIDI signal beig pretty clean, no sysex etc.
>
>I would agree here.  After reading that Penfold book, I built a MIDI to 16x 
>drum trigger + 8x gate interface based on a 6402 and discreet logic.  It 
>ended up being a very big circuit which could easily have been done using a 
>PIC and minimal external components.  At the time though, I was very 
>inexperienced with electronics, and having to learn all about PICs at the 
>same time as trying to learn electronics would have been too much.  The 
>whole project was definitely a worthwhile learning exercise if nothing else :)
>
>And (just like pretty much all of the Penfold circuits) the logic I used 
>will not handle all MIDI eventualities properly.  Having said that, it 
>seems to work pretty well, as long as I set my sequencer to send the right 
>type of note off messages!
>
>Seb
>
>P.S. If anyone actually wants a 6402 chip (they're pretty hard to find 
>nowadays), I have a couple of spares kicking around which I would sell.
>
>