AVR-Chat

--- In AVR-Chat@yahoogroups.com, "Jeff Blaine AC0C" <keepwalking188@...> wrote:

> The most logical conclusion is that
> I am overlooking some footnote ...

You haven't answered Dave's question "What voltage have you got on Vref?".  My guess is that you've wired the VREF pin to some source of 5 volts and overlooked the footnote that says that if you do this you should not select the internal references because a) it won't work and b) you could let the magic smoke out.  The VREF pin is connected directly to the selected reference voltage, the reason for this being that you can hang a capacitor on it to reduce reference noise.  As a result, if you select an internal reference, you must ONLY have the capacitor out there; you can't stick some other voltage on it or it will conflict with the internal reference.  (This is all from ATmega parts, which is one of the reasons I say this is a guess.)

Graham.