> Hello,
>
> I am going to try to implement the solution to the Steinhart-Hart
> equation using a PIC. This equation gives the relationship between
> the resistance of a negative-temperature-coefficient thermistor and
> its temperature. It is an empirically determined equation, so is
> only an approximation to the relationship between resistance and
> temperature. But, it is quite accurate over a large range as long
> as the coefficients are accurate. The thermistor manufacturer gives
> you the coefficients so all you have to do is plug in the numbers.
>
> This is a no-brainer in any high level language and we have it running
> in BASIC here in our lab. However, it's probably rocket science to get
> it to work in a PIC. At least it seems like it to someone who has no
> experience in programming microcontrollers (me).
>
> Can someone give me some advice on how to do this? Are there pieces
> of code already written which can do parts of this (natural log, for
> example)? Are there pitfalls which make it harder than it looks or am
> I over-estimating the effort here?
>
> The equation is: 1/T = a + b(ln R) + c(ln R)^3 where T is in Kelvin,
> a,b, and c are the coefficients provided by the manufacturer, R is the
> resistance in ohms, and the notation "ln" is the natural logarithm
> (base e). I assume the "cubed" term can be done by doing three
> "multiplies" but I don't know about the log and the reciprocal.
>
> Thanks, in advance, to anyone who can get me started on this!
>
> Jim Johnson
>
.....jjohnsonKILLspam.....hpl.hp.com
>