At 11:57 AM 6/14/2005 +0100, you wrote:
> >How about not updating the display unless the difference
> >from the displayed value is > x,  (and set x = 1) ?
>
>Trouble is you do want it to show a drift in value, and I think he has it
>set about right, but possibly needs to expand the count out to about 5 or 6
>from 3, for the number of counts where it needs to be 1 different from the
>current display value.

I guess it depends on the application whether a trend is important. If it's
something like a weigh scale, it might not be important. Once the number
settles, that's it.

I am wary of the "number of counts the same" because it changes the
behavior based on the noise in the signal, which could be different in
the field.

He could also implement a slow low-pass filter and preload it to improve the
response to large step changes (nonlinear filter). Obviously the internal
calculations would be done to a higher resolution than the display.

I usually work very hard to make the system much better than the display,
usually throwing away a decimal digit or more of resolution to get a good
solid display, but then I'm a persnickety instrument engineer type. I don't
want the user to lose confidence in the instrument.

Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com
->> Inexpensive test equipment & parts http://search.ebay.com/_W0QQsassZspeff


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