WB & logging

[rr]

Both hardware filtering and software filtering can be done. With the
DIY-WB I use I placed a .1uf cap at the input to the ADC. This
coupled with the 1K output impedence creates a low pass filter.

If you are interfacing to a GM ECM it is always possible to use
the lag filter routine. This is a first order filter that GM uses on almost
every sensor input.

LDAA     NewVal     ; from ADC
LDX        FiltVal       ; stored from last pass
LDAB     FilterCoef   ; 0 - 255, smaller value is a slower filter
JSR         LagFilter     ; filter it (routine in every GM ECM)
STD        FiltVal        ; Use A for new filtered value

Can also round up A as required:

ASLB
ADCA    #00

Now A has a more accurate rendition of the WB value.

BobR.

Barry Tisdale wrote:

> Any software filter gurus out there?  I'm datalogging my WB & get a good
> bit of fluctuation from reading to reading - looks like noise to me.  To
> smooth things out, right now I'm taking the average of the last 5 readings
> to get current oxy value.
>
> Any better way to do this?  Seems like my method will have a five frame lag
> built into it by doing it this way - makes correlations more difficult.
>
> Any suggestions?
>
> Thanks - Barry
> ----------------------------------------------------------------------------

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