Hello, I am new to uProcs, but most is going well (I can light LEDs, measure temp, measure voltage and do serial communications).

I am a little confused about using Vref for AD converters (specifically 12F675). Is Vref supposed to be the upper end of the measurement or the lower end (i.e. an offset).

E.g. I want to measure from 10-15volts. The ADC can measure between 0-5 volts. So I put Vref to 10volts. Yet this cannot be right, because if I want to simply measure 0-5v, I make Vref = Vdd = 5v.

help?

thanks
d1