Date   : Tue, 19 Apr 2005 12:14:08 +0100
From   : "Colin f" <colin@...>
Subject: Re: Island Logic Music System

 
> This was the way I'd sort-of worked out doing it but never 
> got round to 
> starting - basically emulate a 4000 using midi control.
> 
> There's plenty of books around which tell you how to do such 
> a thing - the 
> Babani MIDI projects book for instance.

Here's one I did earlier...
http://www.colinfraser.com/misc/p6midi.jpg

I'd probably port it to a PIC 18F242 if I made another board, since I no
longer have the AVR programmer.
Also the PIC would have enough pins not to need the encoder IC used (74148).
The AVR maintains a table of which keys are pressed based on midi note ons
and note offs.
While not being interrupted by midi bytes, it continually monitors which
column lines are being strobed on the matrix, and pulls the necessary row
inputs low (or high depending on the matrix design).
This one was designed for the Korg polysix, but should easily adapt to the
Beeb.

Cheers,
Colin f