The caps are 0.1uF caps.

Yesterday evening, I tried using a power supply to provide fixed
voltage, and the ADC stayed spot-on, so I'm thinking you might be right
about the source impedance of the 322.  

So what would be a way around that?  Use an opamp voltage follower?

-David

-----Original Message-----
From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf
Of Wouter van Ooijen
Sent: Wednesday, October 05, 2005 10:58 PM
To: 'Microcontroller discussion list - Public.'
Subject: RE: [PIC] Increasing ADC Accuracy

> I'm using a PIC16F88 with an ADXL322 board for accelerometer readings
> (yes, I have the suggested filtering capacitors in place.)

Which value are the caps? 

And I dunno the 322, but with the 311 the internal resistors are far
larger than the recommended (required?) source impedance for the F88 A/D
(either 10k or 2k5, depends on the part of the datasheet you take).

Wouter van Ooijen

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