Thermistor Lookup Table Generator

Generate NTC lookup tables for firmware with resistance, divider voltage, ADC code, CSV, JSON, and C array output.

NTC table generation and firmware export

Inputs

R25 (ohms) Beta value (K)

Reference temperature (°C) Table mode

Temperature min (°C) Temperature max (°C) Temperature step (°C)

Divider settings

Vcc (V) Fixed resistor (ohms) NTC position

ADC settings

ADC resolution bits ADC Vref (V) ADC denominator

Output format C array name

Include comments

Outputs

Row count-

Mode summary-

Temp	Resistance (Ω)	Vout (V)	ADC code
Set range and parameters, then generate lookup rows.

Set range and parameters, then generate lookup rows.

Generated output

What is a thermistor lookup table?

A lookup table maps temperature, resistance, and ADC codes so firmware can estimate temperature quickly without expensive floating-point math at runtime.

NTC Beta equation table generation

This generator uses the common Beta equation and R25 reference point to estimate NTC resistance over a temperature range.

ADC code lookup table for firmware

Using divider and ADC settings, each temperature row includes expected divider voltage and ADC code for direct firmware use.

C array output for embedded projects

Export rows as CSV, JSON, HTML table markup, or C arrays for microcontroller projects.

NTC lookup examples

Temperature	Resistance for 10k B3950	Approx ADC code	Notes
0°C	~33.6 kΩ	direction depends on divider position	Cold
25°C	10.0 kΩ	~2048	R25 reference point
50°C	~3.59 kΩ	depends on divider position and Vref	Warm
85°C	~1.09 kΩ	toward range edge	High temperature example

Choosing temperature range and step size

Smaller step size increases interpolation quality but also increases table size. Pick practical ranges such as 0 to 100°C or sensor-specific operating windows.

FAQ

Why use a thermistor lookup table?

Lookup tables trade memory for speed and deterministic runtime behavior, which is useful on small MCUs.

How do I generate an NTC ADC table?

Set R25, Beta, temperature range, divider, and ADC settings, then export rows as CSV, JSON, or C array.

Is a lookup table faster than calculating Beta equation at runtime?

Yes. Table lookup plus interpolation is often faster and easier to tune in firmware.

What temperature step should I use?

Common choices are 1°C, 2°C, or 5°C. Choose based on required precision and memory budget.

Why does divider position change the ADC code direction?

NTC-to-GND and NTC-to-Vcc produce opposite voltage slopes versus temperature, so ADC code trend reverses.