> The difference between levels is (ideally) Vref/1024 (not
> 1023), which is the important thing

(trying hard not to labour the issue but just one last thing)

Taking the 4-20mA example, with a 250R resistor and 5V Vref

4mA will develop 1V across the resistor (V=IR). 20mA will develop
5V across it. Now, you can measure up to a result of 0x3ff. But
although 0x3ff is the 1024th level, it isn't FSD. It's up to 0.5 bit short,
if I understood what was posted previously. So I think you would be
able to measure only very close to the full 20mA. I accept the specs
and limitations for a PIC ADC in that regard

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