dc42:
Why are you subtracting 0.5 ? I think that's the source of the problem.
Because that is what was done in the example application that came with the kit, and as I said I was trying to follow that since my initial results without modifying the returned number at all was returning very weird numbers.
http://www.oomlout.com/a/products/ardx/circ-10
It might not be correct I was just trying to get it to work properly.
robtillaart:
Do you have the resistor in place - see page 2 - https://www.jameco.com/Jameco/Products/ProdDS/1468828.pdf -The -0.5 * 100 = -50 * 1.8 = -90 + 32 = 58 degrees F off
76 - 18 == 58 so dc42 is right .
I'm not sure how I'm supposed to wire a resistor into this. According to that Full-Range diagram on page 2, it shows R1 with a negative voltage connected to the Vout. But that doesn't realy make any sense to me, I don't know how to do a negative voltage for one, and for two I don't understand how that would effect the reading. As I said, I'm somewhat new so I'm still learning a lot of this stuff.
So what this thing is actually returning is a fraction of 1 of representing the centigrade temperature? Like .28 = 28 degrees c?
Maybe the one that came with the kit has the .5 mV offset so that it can handle negative temperatures correctly without the negative voltage? I thought I read somewhere on this sensor that the negative voltage wasn't required but according to that diagram it looks like it is if I want to read temperatures below +2 c (and it does get colder than freezing where I live at times so I need to be able to read as low as -10 degrees c.
If someone could help me with how to wire the negative, and explain to me why it is necessary and how it works that would be awesome. I don't want to simply get it working, I want to understand what it's doing an why it's needed.
EDIT:
Guess if I read a little better I might be able to help myself more. Just rereading the stuff from the kit, and it even says there that it has a 500 mv offset in order to read below freezing temperatures. That is why the -.5 was throwing it off, so that make sense, but I still don't understand the negative voltage on this one in order to be able to reading freezing temps.