Quote Originally Posted by spcw1234 View Post
No a pic can not read negative voltages. However the voltage may be shifted to a range the pic can read.

One simple way I see of doing this to offset the voltage is by using a voltage divider to great a "fake" ground for the LM34. If you set this fake ground to +1VDC in refference to your pic's ground that will shift the output of the lm34 up 1000mv. The new range would be +500mv for -50*F and +4000mv for 300*F. Then in PBP remember to offset this value for the correct temp.
How do I connect the floating ground to the pic? Does it need a separate isolated supply? I can't ground the floating ground correct?