Alan B. Pearce wrote :

> >> I want to display the temperature on an LCD.  I'm
> >> using a LM34CZ.  It outputs 10mv per degree F.
> >
> >If you use an external ADC reference of 1.024 V (there are a lot of
> 
> However do remember that a PIC needs a ref of around 2.5V to 
> work correctly.

Good point!

The point *I* was trying to make, was that by carefully
selecting the volt.ref (and maybe conditioning the analog
signal with an opamp), you can *greatly* simplify the
firmware in the PIC. With the "right" input level and volt.ref
you can get the "real world" values directly from the ADC.
(in binary, but anyway...)

This is also clear from the data sheet for the LM34 where
they show a couple of applications where the LM34 is
connected to a standalone ADC and they use what could
be looked at as "odd" ref voltages, but that gives "correct"
values directly from the ADC.

Best Regards,
Jan-Erik.



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