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'Jitter (Was: no subject at all)'
2000\01\11@180007 by paulb

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Richard Fleming wrote:

> I'm using the A/D line and having trouble with when the pots are
> between bits ie `00000011'  to `00000100' etc

 It's all in the specs.  A/D converters are specified as giving an
output +/- 1 bit.  If the input is marginal (i.e., on a boundary) it
will by definition flicker from one to the other.  This just tells you
it's working correctly.

 Knowing this will *always* occur, you decide what you want to do.  If
you don't want your output jumping, include hysteresis so that it only
*changes* if the ADC reading varies by 2 or even, 3 counts.  This will
be much more comfortable.  If you think you have lost resolution, you'll
just have to get some more resolution somehow.

 If you're reading pushbuttons or any mechanical switches, this same
procedure is called "debouncing".  One method of obtaining increased
resolution is to average a number of readings over time.

 This is exactly how you perform debouncing of a switch, so you may
care to use a debouncing algorithm i.e., if your ADC reading is, over 20
successive reads, the same each time and also different to what it was
before, then you accept that it has changed "for good".  The new reading
is implemented and becomes the "old" reading for comparison.  If it
however it changes by *many* counts, you will have to implement that
change promptly.
--
 Cheers,
       Paul B.

2000\01\15@172854 by Mark Willis

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(Been Thinking 'bout this one;)  My input here:  James may read your
post, and I and James sure will - I believe that some of us will usually
read it sooner if you "intrigue" us with a good header line, that's what
I find I look for for the messages I read first;  A post that may give
me a chance to learn or to help others, either's good <G>

Sometimes when (I'm busy) && (I'm way TOO busy) && (I have tons of list
messages to read) && (Cannot do 'em now), I don't get to all list
messages right away;  I do try to come back & catch all "unanswered"
threads later, though, sometimes some mis-topiced posts have goodies in
'em.

It's sort of a, "You get more responses faster with honey than vinegar,
you'll have a response anyways" thing <G>

 Mark

James Paul wrote:
>
>  Boy, if the lack of a subject line was all I had to worry about,
>  what a wonderful life it would be.  I understand your feelings
<snipped>

--
I re-ship for small US & overseas businesses, world-wide.
(For private individuals at cost; ask.)

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