I am building a board with an ADC on it which is to measure these two sensor types.
The tricky bit is the linearisation.
All the equations I can find come in multiple parts.
coefficients below 0C and above 0C. But you don't know the temperature until you have evaluated the equation! So you could end up in a situation where the algorithm oscillates between the two equations.
Same with thermocouples, e.g. here
I have found some thermocouple equations which cover the whole range with one polynomial e.g. the NIST Polynomial Coefficients for Temperature-to-Voltage Conversion. However I have found these for only some of the eight thermocouple types. I am trying to support B E J K N R S T types.
How do instrument manufacturers deal with this? Do they store a lookup table and interpolate it?
I can see that with some effort one could write software (running on a PC) which takes in these equations and generates lookup tables for the whole lot.
Is there some easier way?
Maths is not my strong point although I can write C code to evaluate a polynomial.
Very many thanks for any tips.