[sdiy] while we're talking about scaling & biasing etc

[Ingo Debus]

Am 24.05.2009 um 05:48 schrieb Jerry Gray-Eskue:

> 1 The Micro you are using has an analog input mux and it is looking at
> different pin.
> 2 The D2A is not setup correctly and so is not reading the voltage  
> on the
> pin. This setup can be tricky with a number of registers and bit flags
> involved.
> 3 The Port Pin you are using has not been configured as an analog  
> input.
> 4 You are setup for an External Reference and this reference  
> voltage is
> missing.

But then it wouldn't work with a known good DC voltage source either.  
As I understand it, Jason has checked this and it worked ("a pot from  
5v").

Perhaps the opamp driving the ADC input pin is oscillating? Jason,  
did you check the opamp output with a meter or with a scope? A meter  
might average out the oscillaton while the ADC, being much faster,  
gives random numbers.

Two separate regulators shouldn't be a problem, as long as they both  
share a common ground.

Ingo