Hej Vyas. Tack f=F6r ditt meddelande 15:37 2002-10-07 enligt nedan:
>Hi Morgan,
>
>Sorry for delayed response.
>I am using 0.1uF polypropylene cap, soldered right on the pins.=20

Seem OK for 4MHz.

>Clock is internal 4Mhz.

Stable freq is mandatory for slope converters, thus Xtal is better!

>I tried using Sleep mode, but it not does not wake up. Somehow the capture
>interrupt is not working. I had this problem from beginning. So I am using
>simple wait till !OVFIF. So sleep is out.

That should be good enough.  I dont remember how i did.

>You have mentioned about AD Clock speed selection, I think you mean AD
>current selection, because I can't find anything in data about selecting
>clock speed.

Ah, yes you are right.  You can only select internal or external osc.=20
(That switch was locked in one position in early silicon, BTW) =20

I got better results with external Xtal osc.  I used max possible 20Mhz for=
 max sample rate, then filtered to increase precision... or more correctly=
 reduce noise.. i guess precision is not state of the art...

> The AD cap selection and AD current selection go hand in hand.
>I will have go with MOMA filter.
>
>Whole purpose of using PIC14000 was for 16 bit adc, if I can't get 16 bit
>resolution, I will have to trash the project.

Unless you really want your nose bleeding, connect every PIC14000 you have=
 to mains voltage directly.  Then pop some for me too, hehe.  My nose still=
 bleeds...

The only solution is a nice delta sigma, like LTC2400.  24 bit, or faster=
 with less bits.  Even does 50/60Hz rejection at appropriate clock speed. =
 Beware of early silicon there too, there was a bug in readout in one of=
 it=B4s modes, a particular timing, and of course I used that combination...=
  Also avoid MAX110/111 and some other MAX (internal test lockup bugs). =
 Whats up with AD converter quality anyway, every A/D i have used have shot=
 me in my back!!  AAARGH!

(For bug details search PIC archive on LTC2400 and MAX110 i posted a couple=
 years ago)

/Morgan

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