Re: [avr-gcc-list] ADC anomaly

[Douglas Dotson]

I'll give it a shot. I haven't brought many of the
other on-chip peripherals online other than the
USART. I am filtering the readings through a 
simple digital filter which is working well. This
problem is very slow moving. I have 3 channels
of the ADC operational and the other channels
are not showing any similar behavior. Strange.

DOug

--- Mattias Svensson <address@hidden> wrote:
>  >>The 3 LSB difference in your case could be
>  >>temperature drift due to the
>  >>device heating up during your several hours test.
>  >>
> 
> > I thought of that, but the temperature is pretty
> > constant during the test. I'll check that out
> though.
> > The resistors in the circuit are 1% so I wouldn;t 
> > expect that much of an error. Seems that the
> system
> > settles to 508 counts, but is 511 or 512 after a
> > reset. Only a second so I don't think that
> temperature
> > is a factor in such a short time with
> uninteruppted
> > power.
> 
> Try using the ADC noise canceling techniques
> mentioned in the datasheet
> if you need better accuracy.
> 
> Maybe you are doing something with the device
> peripherals that causes 
> interferance on chip level...
> 
> /Mattias
> 
> 
> 
> 
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