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I understand that, but I would like to maintain 10-bit or greater resolution through the averaging algorithm.

Regards, Bob

Bob Axtell <cr_axtell@YAHOO.COM> wrote ..
> To make 10bit A/d into 8-bit, just shift right twice. That's it.
>
> --Bob
>
>
> At 11:33 PM 7/16/2003 -0500, you wrote:
> >Andy, just one question.  How would you change the code to handle a 10-bit
> >a/d sample?  Probably not necessary in the case where I'm determining
> fuel
> >level (1/256 is plenty of resolution), but I'm curious if it can be done
> >yet kept simple.  I suppose I could really make the fuel gauge rock-steady
> >by using this algorithm along with sampling around 250ms or so...
> >
> >Regards, Bob
> >
> >Andrew Warren <aiw@CYPRESS.COM> wrote ..
> > > Bob Japundza <PICLIST@mitvma.mit.edu> wrote:
> > >
> > > > I have been thinking about the tanks sloshing around as being
> > > > noisy signal, and that is one of the reasons why I've been
> > > > contemplating the median filter.  Do you have a better suggestion?
> > >
> > >     Seems to me that a straight low-pass filter would work well.
> > >
> > > > I tried an analog low-pass RC filter, and didn't have good luck
> > > > with it, because of the low resistance of the senders (30-240 ohm
> > > > Stewart-Warner float types) and not to mention it made me nervous
> > > > to have large caps tied to the fuel senders, in an airplane, no
> > > > less.
> > >
> > >     Try a digital low-pass filter.  Given a series of input samples
> > >     in the range 0-255, this code (all 7 words of it) should perform
> > >     a 256-sample moving-window average and give you the filtered
> > >     result in AVEHI.
> > >
> > >     ; Run this on every input sample.  Enter with the new input
> > >     ; sample in NEW.  Exits with filtered result in AVEHI, and
> > >     ; NEW unchanged.
> > >     ;
> > >     ; Might want to initialize AVEHI to something reasonable at
> > >     ; program start; if it were me, I'd probably just initialize
> > >     ; AVEHI to the first input sample.
> > >     ;
> > >     ;          (WIDTH-1)*AVE + NEW
> > >     ;    AVE = -------------------
> > >     ;                 WIDTH
> > >
> > >     AVEHI   EQU     [ANY FILE REGISTER]   ;Holds the average [0-255].
> > >     AVELO   EQU     [ANY FILE REGISTER]   ;Holds the fractional part
> > >                                           ;of the average.
> > >     NEW     EQU     [ANY FILE REGISTER]   ;Holds the new sample.
> > >
> > >     FILTER256:
> > >
> > >         MOVF    AVEHI,W
> > >         SUBWF   NEW,W
> > >         SKPC
> > >         DECF    AVEHI
> > >         ADDWF   AVELO
> > >         SKPNC
> > >         INCF    AVEHI
> > >
> > >     -Andy
> > >
> > > === Andrew Warren -- aiw@cypress.com
> > > === Principal Design Engineer
> > > === Cypress Semiconductor Corporation
> > > ===
> > > === Opinions expressed above do not
> > > === necessarily represent those of
> > > === Cypress Semiconductor Corporation
> > >
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