At 02:01 PM 5/19/00 +0200, Quentin wrote:
>My A/D input signal is such that I will always have a +/- 10 fluctuation
>in my register value. Can somebody tell me how to get an average reading
>over say 5 A/D samples?

If your readings are periodic, one method is to pick a constant 'a'

and do  value = (1-a) * value + a*reading

(you might also use a flag to preload value=reading the first time.

This forms a low pass filter, and more recent values have a higher weight
than previous values. It has the advantage that it only uses one ram
location and you get a value every A/D conversion.

If you just want to take a bunch of readings in succession and average
them, just add n values together and then divide by n. Obviously you
need to avoid overflow during the add, so you might use 16 bit math
for an 8/10/12 bit A/D reading with 256/64/16 values or less being
averaged.

Best regards,


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