Grrrrrr!  Why do people constantly put their personal email addresses in the
"reply-to" field?  If you're posting the discussion on the list, you're
gonna get replied to on the list, dammit!

>I am attempting to do a A/D conversion to a signal ranging from -1 VDC to
>+5.5. VDC.  I am using a PIC16F877.  I understand to need to use the VREF,
>+VREF, and -VREF pins in order to do this.  The problem is that I have not
>found a good description of how to use/apply these pins.

This may be out of spec.  The analog input minimum voltage spec for Vain and
Vref- is Vss-0.3 Volts.  I don't know what the chip would do with
-1.0 V.

But other than that, I would imagine you could put whatever voltages you
wanted for Vref- and Vref+, as long as they were in spec.  Use a voltage
divider or voltage reference diode for the pin levels.

Configure your A/D control registers for whatever you want, i.e., select
channel/clock select bits in ADCON0 and set justification and Analog/Digital
pins in ADCON1.

Looks like you've got a lot of options with which pins you can use for
analog input and Vref's.

--Andrew
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