Looking for controller build hints..

[Paul Maddox]

Andy,


  Easist way would be to use one ADC, and an analog mux
to get samples from upto 256 knobs/sliders if you should wish.
Interfacing to midi is easy (its just serial data, just a funny
baud rate 31.25Kbaud) and interfacing to something like an
LCD is easy if you get one with the Hitatchi controller on..
  As for a CPU, Id use an Atmel 8515, but Im biased, I love
this chip...

  But Id check out this first ;-

http://www.doepfer.com/db_e.htm

  Is 64 pots enough?

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-----Original Message-----
From:	Andy Mucho [SMTP:andy at software-superstars.com]
Sent:	Wednesday, October 27, 1999 12:46 AM
To:	synth-diy at mailhost.bpa.nl
Subject:	Looking for controller build hints..

Hi all,
I was kind of wondering if anyone had any hints for a new fangled idea I
thought I'd build in my spare time..
Basically I want a big panel of knobs and sliders that will produce MIDI
CC's at MIDI rates, and/or optionally at much higher sample rates through a
parallel or high speed serial port.
Ultimately I'm looking at approx. 160 pots of various forms. I'm willing to
build since everything I see out there just doesn't suit my needs. I've
already got 3 Phatboys that are fine and dandy, and I thought about a
BitSream Pro, but nothing really seems to suit exactly what I want in terms
of twiddlies.
Not knowing anything about how to build this (but well qualified on the
low-level software department) I'm wondering if anyone has any hints..
My question centres around the principle for handling such a large number of
pots..
I presume this kind of set-up would be done using an A/D for each pot, with
some kind of wacky multiplexing to read the pots in a round robin fashion?
Or perhaps not?
Any recommendations on how to do this multiplexing?
Any tips for a CPU that can be *easily* interfaced into such a set-up, with
say onboard ram, flash rom, serial ports, and perhaps a simple way to
interface to an LCD?

And as a minor (but intriguing for me anyway) thought, how wacky would it be
to implement all of these pots/faders as automated pots? Are these radically
expensive and difficult to implement into such a scheme, or should I just
forget this?

Regards
AndyM