adc resolution

butterfly · Joined: 04 Jun 2006 Posts: 35

pic can only get analog date 10 bit. i want to use over simpling and over avaraging.. I found a way using nyquist theory.. i use adc module like:
#device adc=10

for over avaraging can i use like that:

#device adc=12

thanks for help

SherpaDoug · Joined: 07 Sep 2003 Posts: 1640 Location: Cape Cod Mass USA

You will have to roll your own oversampling and averaging. To get 2 more bits you need 16 samples IF there is GAUSSIAN RANDOM noise. In practice I find this works poorly because the noise is often not quite random and never really gaussian.
However it is easy enough to try, just sum 16 samples and divide by 4 and see what you get.
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kender · Joined: 09 Aug 2004 Posts: 768 Location: Silicon Valley

The oversampling issues have been discussed in some detail here:
http://www.ccsinfo.com/forum/viewtopic.php?t=24375

Here are some technical notes give a good overview of dithering and oversampling. Although you might have seen them already.
http://archive.chipcenter.com/TestandMeasurement/tn033.html
http://archive.chipcenter.com/TestandMeasurement/tn034.html
http://archive.chipcenter.com/TestandMeasurement/tn035.html