Connect the NTC to a voltage divider with a known resistance, measure the voltage with ADC and convert it to temperature with the corresponding sensor characteristics.

What to check out

• For ESP32, use a divider and supply voltage that does not exceed the permitted ADC range. Check ADC and GPIO restrictions for a specific family.
• R NTC = R ref × V mer / (V nap - V mer) shall be used to bind the reference power resistance and the NTC against mass. The formula applies to this arrangement.
• Convert the resistance by certified R/T-table or coefficients. Do not enter random B-value just because the probe is 10 k?.
• Check several measuring points, effect of current through the sensor and operation at disconnection. In the program, separate temperature from error.

A Practical Example

At a voltage close to half the charge, the resistance in such a divider is approximately the same. This is a useful electrical test before you trust the output temperature.

Common error

12-bitni ADC doesn't mean automatic precision to a thousand degrees. Important are the input range, ADC calibration, resistance tolerance, sensor and thermal contact.

For further reading

• Espressif: calibration of the ADC analogue converter (English). Official procedures for converting ADC measurements into voltage and reducing measurement tolerance.

Compatibility check products

Select products according to the above criteria; the list is not a confirmation that they are all interchangeable.

• Inox probe NTC sensor for a temperature of 10K 0,5m cable
• Arduino nano clone with USB C connector CH340
• ESP32 38 pin WIFI IoT Bluetooth
• Mini OLED screen for Arduino 128x64 pixlov 0.96in i2C Blue