Poly Keyboard Interfaces

[Colin Fraser]

On May 3,  9:33am, gstopp at fibermux.com wrote:
> Subject: Re[2]: Poly Keyboard Interfaces
>
>      The thing that really needs developing is a good multi-output
>      MIDI-to-CV converter. When I say "good" I mean different assignment
>      options, programmable split points, multiple MIDI channel support,
>      things like that. When I say "multi-output" I mean 8 CV's, 8
>      velocities, 8 release velocities (maybe), bend, mod, aftertouch,
>      volume, and some continuous controllers. Heck maybe 16 CV's and
>      velocities. If you want to get really fancy you can put an arpeggiator
>      in there somewhere (although I'd prefer to leave that in the
>      controller I think).

My own home-built midi to cv convertor has 32 cv outputs plus din sync.
The first 16 channels are output to jacks, the last are hardwired to 4 SSM
2024 quad vcas in a built in 8-2 mixer.
Ouputs can be assigned to note velocity, controller or gate, on any midi
channel, with upper and lower note limits to allow splits to be programmed.
Pitch bend and aftertouch are TBI, as I don't have a controller keyboard with
them.
The DAC used is an 8-bit thing, but another convertor I built for a friend is
shortly to be upgraded to 12 or 16 bits, to give a software selectable linear
control voltage for a Korg.


>      So now we're back into that need for a CPU and a editor/compiler/EPROM
>      burner setup. But the hardware is back to a slim CPU/RAM/EPROM/DAC
>      plus a big honkin' analog mux. If 4067's are used then we could easily
>      go 64 or 128 CV's. The MIDI parsing code becomes the fun part, as you
>      say.

My hardware is baced around a 6502, eprom and ram, 6850 uart, a few latches,
decoders, op-amp buffers etc, and 4 x 4051 demuxes.
It was originally developed as a hardware add-on for a BBC microcomputer,
hence the use of a 6502.
If anyone's interested in the code, I can mail it to you. It's written in BBC
Basic, using the in-line assembler, then blown onto eprom from the BBC.


Peace

Cf

-- 
Regards,

Colin Fraser


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