Hardware design fault ???
Hi,
While carefully reading your Datasheets ...
Did you notice the ADC input impedance had slightly changed ??? ... take care to the voltage source impedance !!! ( in your RC filters ... there's a series resistor !!! )
Your "symptoms" make me think it's a source impedance problem ...
Also consider the voltage offset of your buffers ... An AOP gives easily 10 mV offset !!! and from a batch to another, it can widely differ.
Could you show us a scheme of your input circuits ???
I Use a 2520 for my Honda Lawn tractor ( read air and oil temp - LM335 , plus oil pressure - MPX 5700 , with the inboard ADC) and readings are rock steady ...
My ref is a 4.096v from a TL431a ... trimmed with a 4.5 digits multimeter ...
The initial project was built around a 18F452 ... and I didn't notice any change.
Alain
Last edited by Acetronics2; - 8th March 2008 at 18:01.
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Why insist on using 32 Bits when you're not even able to deal with the first 8 ones ??? ehhhhhh ...
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IF there is the word "Problem" in your question ...
certainly the answer is " RTFM " or " RTFDataSheet " !!!
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