Hi guys,
If I use a voltage divider to get maybe 0.05v on the aref pin, in theory I should be able to measure voltages down to around +/-0.0001v kind of range (ball park figure). Is this genuinely possible? It sounds to good to be true, and I can't find any literature in the datasheet to either confirm or deny it.
Thanks in advance,
Deeksie
Page 323.
ADC Characteristics
Reference Voltage: minimum: 1V
I dont know just how good the ADC is but with 1v reference, you should be able to achieve .001v precision.
Just noticed I hadn't replied much earlier, how rude of me! Thanks for your help, you cleared up the question for me. 
The only way to measure voltages (with an a2d) down to the tenth of a millivolt range with any accuracy is to use an amplifier and measure the amplified voltage