MCP9701.... I think my temp calculations math are off....

I see you are using the Steinhart-Hart equation, very nice!
I follow what your code does except could you explain this equation please?

var ohms=10000*val/(1-val);

It seems like there should be a factor of 1023 in there somewhere (see here) and maybe something for the voltage too (see here), but perhaps I just don't understand it all (haven't actually tried it myself yet).

Currently, val is some number between 0 and 1023. Lets see what happens to val/(1-val) for some example values:

val  :: val/(1-val)
5    :: 5/(-4)      == -1.25
100  :: 100/(-99)   == -1.01
300  :: 300/(-299)  =~ -1
500  :: 500/(-499)  =~ -1
1000 :: 1000/(-999) =~ -1

I think you see that something must be wrong here. I am thinking val needs to be normalized to a fraction of 1, ie, something like val/1023.

Also, I am curious how you went about calculating A, B, and C, ie, how did you stabilize and accurately measure the 3 temperature points as well as the 3 resistance values at those temperatures?

Thanks!