Lpc2000

At 01:47 PM 9/16/04 +0100, you wrote:
>I'm trying to read an analogue signal using the internal ADC, but it seems 
>to have problems readding small signals. My analogue signal goes from 0 to 
>3V, in increments of about 1mV, but when reading the signal I get a range 
>of readings, and it doesnt seem to settle. I'm reading every 100msecs this 
>signal.
>
>p.e. when the signal is locked at, lets say, 10mV I get an oscillatory 
>reading that ranges from 6 to 10mv.
>
>Has anyone dealt with this problem? any clever solution?

Umm, isn't that on the order of +/1 count?  That basic nature of discrete 
conversion will give you that much uncertainty.

If you need to resolve to better than 1 part in 1000 you will need a higher 
resolution (and accuracy) convertor.  You could get a greater dynamic range 
with a higher resolution convertor, a PGA (programmable gain amplifier) or 
a non-linear amplifier.

Robert

" 'Freedom' has no meaning of itself.  There are always restrictions,
be they legal, genetic, or physical.  If you don't believe me, try to
chew a radio signal. "

                         Kelvin Throop, III