Thanks Neil. I meant AVR. Not PIC. Too many things going on. John ----- Original Message ----- From: "Picdude" To: Sent: Wednesday, May 07, 2003 10:40 PM Subject: Re: [PIC]: Using the internal voltage reference w/ADC Since you've used the [PIC] tag, I'm assuming you mean the ADC inside of a PIC. But what do you mean by "internal voltage reference .... that is set for 2.5V"? The voltage references (+ and -) on the 16F8xx chips (the ones I'm familiar with) are really just the supply rail voltages (Vdd and Vss). So do you mean that you are powering the PIC from 2.5V? If so, then is your signal derived from the same power rails? It may be ratiometric depending on how/what the signal is coming from. Or are you referring to some other ADC? A voltage divider is fine, but just choose the percentage accuracy of the resistors to get as accurate as you wish, or actually measure them. Cheers, -Neil. On Wednesday 07 May 2003 18:58, John Pearson scribbled: > When you have an internal voltage reference for the ADCs, that is set for > 2.5 volts, what is the usual way to interface a 0-5v signal. Just use 2 > resistors as a voltage divider? Or is there a more acceptable method? > > And how good are the internal references. Is a person better off using an > external reference? > > Thanks > > John -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics