[sdiy] midi clock

Wed Dec 4 18:20:18 CET 2002

I'd trace the keyboard matrix very carefully...then have a
PIC (or similar) decode the midi note-ons and close analog switches
to emulate the matrix.

I would not bother trying to do the tempo...because you will have
no feedback as to what tempo the Casio was at to start...or any way
of syncronising.

H^) harry

--------Original Message--------  

From: elmystico at earthlink.net
To: Seb Francis <seb at is-uk.com>, pfperry at melbpc.org.au
Cc: synth-diy at dropmix.xs4all.nl
Sent: Dec 04 2002 10:44
Subject: Re: [sdiy] midi clock

>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 
>>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.
>>
>>