Quote Originally Posted by scottl
I have been racking my brain for the past two weeks with the following!

I have a PIC12F675 reading an AD595 thermocouple IC. The AD595 provides 10mV/C. In order to read the temp below 0 I have added a voltage divider to the ground pin of the AD595. I have also power the AD595 via a -5V to +5V power supply. I read the output of the AD595 on GPIO.0 and the Virtual Ground voltage via GPIO.1.

To read the temperature above 0C I basically subtract GPIO.1 from GPIO.0. I cannot get the math correct for any thing below 0C or 32F.

I will handle the sign output later!

Can anyone point me in the right direction with the math?

Thanks in advance,

Scott

I saw the AD595 datasheet and for temp below 0 degrees Celecius the
output -ve. As U have stated that that U have added voltage devider to gnd
pin of ad595 but whether the input to PIC is above 0V or not? U must have
output of AD595 at 2.5V or half the reference supply of PIC. Then 0 degrees
would correspond to 128 in 8bit mode. this way may be Ur maths will work if U are gng to add - sign later