KŸbek Tony <PICLIST@MITVMA.MIT.EDU> wrote:

> I have an recursive moving average filter, 52 points with 3 bytes
> each, which works ok. However the ram usage is 'a bit' high :-) (
> almost the entire two top ram banks on my 16f876, )
>
> Are there any other, more space conservatory, techniques one could
> use to accomplish the same filtering ?

Tony:

The usual way to solve this problem is this:

    TEMP = AVERAGE * WIDTH
    TEMP = TEMP - AVERAGE
    TEMP = TEMP + NEW_SAMPLE
    AVERAGE = TEMP/WIDTH

If you do it that way, you need only enough storage for TEMP,
AVERAGE, and your NEW_SAMPLE.  If you set WIDTH to a power of 2, the
multiplication and division become trivial; if you pick a value of
256, the multiplications and divisions don't even require any code.

-Andy


=== Andrew Warren - fastfwd@ix.netcom.com
=== Fast Forward Engineering - San Diego, California
=== http://www.geocities.com/SiliconValley/2499