Updating HPWM frequently, safe?

**Darrel Taylor** · - 8th May 2007, 08:31

I tried every AD oscillator / Sample time possible, and it made no difference.
Even with the A/D input tied directly to ground, it was getting crazy readings between 0 and 20.

After I tried it with a 12F675 (without the CCP) and got the same results,
I finally figured out that I had removed the big cap on the power lines on this protoboard.
Probably needed it for something else. Doh!

After putting a 100uf cap across the power supply, everything calmed down again.
It's still not perfect, but I think that has alot to do with the breadboard.

So then to really stabilize things I added an averaging routine, and I think that's about as close as we're going to get.

First make sure you have enough capacitance on your power lines (I think mister_e already suggested that).

Then add this to the bottom of the program

Code:

' -=-=-=-=-=-=  Average Analog values -=-=-=-=-=-=-=-=-=-=
Avg       VAR WORD
AvgCount  CON 16
spread    CON 20

Average:    ' Smooth data
    IF ABS (pote - Avg) > spread then
        Avg = pote
    else
        Avg = (Avg*(AvgCount-1)+pote)/AvgCount 
        pote = Avg                               
    endif
Return

And also, just after the ADCIN statement, add this

Code:

    gosub Average

HTH,

**mister_e** · - 8th May 2007, 20:20

it's getting interesting... i have everything on hand, will do some test here.

Sorry, i was suppose to do it yesterday

**peu** · - 8th May 2007, 20:30

well I hope you find something because I tried adding a 100uF capacitor in the power lines or in parallel with the wiper and my problems remain, even after adding the averaging routine provided by Darrel.

I even started looking for other pic alternatives

in case this can't be solved...

Thanks again