Most likely it is not that PIC ADCs are crappy but the analog
circuits or layout is crappy.

Microchip AN688B (Layout Tips for 12-Bit A/D Converter 
Applications) may be a good reference for you even though it
dealing with an standalone A/D converter.

The environment of the circuit boards can play a big part
as well. If you do not have a proper layout, the noise
can affect the ADC result by a lot.

Regards,
Xiaofan

-----Original Message-----
From: David de Regt
Sent: Thursday, October 06, 2005 12:20 PM
To: piclist@mit.edu
Subject: [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.)

I'm trying to figure out how to get maximum accuracy out of this.  Right
now, the best I can seem to do is average over 100-ish ADC samples,
using the $80 flag on ADCON0.  Even this, however, is still getting +/-
7 or so accuracy on the ADC-ing.
 
Is there any way to make the ADC more accurate, or are the ADCs on the
PICs just fairly crappy?
 

Thanks,

David
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