> I'm using the PIC 16F877's ADC unit to determine voltages, and I want a
> Vref+ of 24V.  Is this possible?

No.

> The datasheet seems to say no,
> but I'm not sure.
> The maximum value of Vref+ is stated as AVdd + 0.3, but I'm not sure
> what "AVdd" is.  What is meaning of the "A" in AVdd?

Analog.

> Then again, the spec
> also says that Vref+ - Vref- can be no more than Vdd + 0.3.  Correct me if
I
> am wrong, but it seems that I cannot use a 24V input direct to the ADC.

That's right, you can't.

> I suppose I'll have to use a voltage divider to get the input's max to
> something within specifications, but is there a better way?

As long as 10 bits over the 24V range is sufficient, a voltage divider is an
easy and effective answer.


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