Thermistors and RTDs

NTC: Beta & Steinhart–Hart — the Beta model R = R0·e^(B(1/T − 1/T0)) from R25 and B, or the Steinhart–Hart equation 1/T = A + B·ln R + C·(ln R)³ fitted exactly through three calibration points (better than ±0.1 °C over a wide range). Convert either way and print an R–T table.

Divider into an ADC — the sensor and a fixed resistor across a ratiometric ADC: voltage and counts at each temperature, the temperature step one LSB represents, the fixed resistor that gives the best sensitivity mid-range, and the self-heating error ΔT = P/δ.

RTD — PT100, PT500 and PT1000 with the IEC 60751 Callendar–Van Dusen coefficients (A = 3.9083×10⁻³, B = −5.775×10⁻⁷, C = −4.183×10⁻¹² below 0 °C), the class AA/A/B tolerances, and self-heating at your excitation current.