dax2@hotmail.com wrote :

> It doesn't have to be instantaneous in processor time.
 > I'm willing to go a few cycles. I doubt anyone would
 > notice a few microsecond of lag time.

Now, are we talking about what can be "noticed" by an
human (eye) ? Then even a few *millisecons* or a few
*10's* of millisecons would probably be just fine.

It's probably quite a difference between "a few us" and
"a few ms" when it comes to designing the (external)
signal smoothing circuit. From something fast using
active (opamps) components to simple things using
maybe only a few passives.

Now, if you realy need "a few" (5-10 ?) *us* response
time, well so be it.

Another important design criteria is what the volume
is. If these "products" are ment to be made in large
quantity, one might look into simpler hardware and put
more of the "logic" into the firmware. If low volume,
it could be wise to simplify the firmware by adding
some extra hardware...

Jan-Erik.

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