Hi Richard,

I knew you'd be the first to respond

I've been monitoring the output (pin 8) throughout the testing and it doesn't go above ground at any stage. Ultimately I want to process the opamp output with AN6 (or another if this isn't possible) and is how I initially breadboarded it, but when nothing worked I tried disabling the ADC module and repeated all tests. Zip, diddly squat, nada.

The data sheet and some of the App Notes rave about the specs of the internal opamp and, yes, it is Rail to Rail IO.

I have the pcb space to put in an external opamp (probably use an instrument amp) but don't see why I should and, sooner or later, I will need to use this feature so it's worth pursuing.

Cheers,
Bill