Ok, I will try as suggested and see what happens.

Thank you for the info.

-----Original Message-----
From: pic microcontroller discussion list [mailto:PICLIST@MITVMA.MIT.EDU] On
Behalf Of M. Adam Davis
Sent: Sunday, April 18, 2004 10:58 PM
To: PICLIST@MITVMA.MIT.EDU
Subject: Re: [PICLIST] [EE:] Reading different resistor values

As shawn stated, op-amps are fairly simple, but you can certianly give
it a try with just a resister.  The 10k impedance problem  simply means
that voltage levels will measure less than what they actually are.  The
real issue here is that once you go outside the specification the one
PIC may not work like the other, so the circuit and program you make may
work fine on one PIC, but you might have to change the program slightly
on another PIC.  Alternately it may work at room temperature, but it may
change slightly in colder temperatures.  In most cases I suspect you
won't even run across these problems.

To give yourself maximum range, I'd use a large (8k to 10k) resistor,
then hook it up to the PIC and read the values out.  If they are
sufficiently distenguished (they should be) then you can use just the
resistor.

So, as a one off, you should be fine with a resistor and setting the
levels inside the PIC by hand.

-Adam

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email listserv@mitvma.mit.edu with SET PICList DIGEST in the body