Kerry Wentworth wrote:
> So, your Filt is a 32 bit number in 20.12 format?  Odd that you didn't
> mention that before.

As I said several times now already, FILT has -Log2(FF) extra fraction bits=
..
When FF =3D 1/16, you only need 4 fraction bits, but since bits come in chu=
nks
of 8, it's OK to use 6 fraction bits out of a 16 bit number if the integer
part only needs 10 bits.

Sometimes I do use wider values for the filters.  As you should be able to
see by now, it all depends on FF.  Multiple filters chained together also
require more bits if you want to represent every last bit of detail in the
original value.  Often that is not necessary.  Just because the math can
provide the filtered value to one part in 2**30, it doesn't mean it's usefu=
l
and you therefore don't have to bother computing to that accuracy.

> Is there any chance of you providing a snippet of
> code that implements your version of the filter?

Look around, there's bound to be stuff out there.  It's not "my" filter.  I
was just describing the basic one pole low pass digital filter people have
been using since the first bits were invented.  I've implemented filters
based on that principal many times, both on PICs and in host software.  Som=
e
of it is probably out there somewhere, but I can't think of specific code
right now.


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