AVR-Chat

> Differential inputs measure the difference between the two inputs.
> If the - is at 3V, and the + at 4V, then you'll see 1V.
> They are commonly used for measuring current, with a sense resistor.

Yes, that part I got, but in the table there's differential inputs with
(one example) ADC0 in both positive and negative column. I was sort of
hoping I could use it as I would a single ended input but with the gain
available. I've now tried and can't get it to work so I'm mostly curious
why those combinations are in the table in the first place, and not
marked out as unusable or something...