Looking for controller build hints..

[Harry Bissell]

Yep... multiplex in round robin fashion is the usual method... look for some
number of bits change (to get rid of vibrational and electrical noise... ) then
update the values. A list member pointed out to me (us) before that this works
very well given the human inability to move more than five or six pots at a time
(two would be most common)...
Fancy software could update the moving pots at a higher rate to avoid the
dreaded "zipper noise"...

If you aren't controlling audio, the zipper isn't a problem...

:^) Harry

Andy Mucho wrote:

> 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