Octavio,

At 05:33 PM 9/23/97 -0300, you wrote:

>I have another question about this. One of my pic aplications is a cow
>scale,
>I do my best to keep it still but you can imagine how the cow listen to
>me,it don't keep still at all.
>The filtering I'm doing is: VAL=(LASTVAL/7+NEWVAL)/8
>I know thie is not the best way, is the median average better in this
>case?
>
>Regards,
>
>Octavio

I had a friend in the '70s who designed a scale for sheep/goats. Whilst he
did not use a PIC, his approach may be of value to you.

His strain gauge sensor output was amplified and then put through an
adaptive filter before being digitised and displayed. His adaptive filter
was simply a low pass RC filter with the C being connected to ground via
4016 transmission gates. The first time on the scale, the filtering was very
short in time constant, allowing a quick attack. The time constant was
automatically adjusted by switching in progressively larger C values so that
the effects of dancing by the animal was filtered out quickly resulting in a
near perfect reading in a relatively short time. And no need to learn
sheep-speak .....

Perhaps you could use the PIC to switch filtering/averaging in your analogue
path in a similar way.

HTH,

Regards,

Ross McKenzie
Melbourne Australia