Thermistor Component

The Thermistor APIs provide a set of functions to read the temperature from a thermistor. The thermistor stores the relevant information (from the datasheet) such as the B value, the nominal resistance, circuit configuration (upper or lower part of the voltage divider), the fixed resistor value, and the supply voltage.

It uses these data to compute the measured resistance of the thermistor, from which the temperature can then be calculated using the Steinhart-Hart equation. See the Wikipedia article for more information.

Using the Steinhart-Hart equation, the temperature can be calculated using the following formula:

Math

    T = \frac{1}{\frac{1}{T_0} + \frac{1}{B} \\ln \frac{R}{R_0}}

where:

$T$ is the temperature in Kelvin
$T_{0}$ is the nominal temperature in Kelvin (e.g. 298.15 K, 25 °C)
$B$ is the B ( $β$ , beta) value of the thermistor (e.g. 3950 K)
$R$ is the resistance of the thermistor, measured in Ohm
$R_{0}$ is the nominal resistance of the thermistor (e.g. 10000 Ohm at 25 °C)

Note: the thermistor component assumes that the thermistor is used within a voltage divider circuit, with a fixed resistor. The component can be configured so that either the thermistor or the fixed resistor is the upper part of the voltage divider.

Example

The example shows how to use the thermistor component to compute the temperature from a temperature sensitive resistor (thermistor) - specifically negative temperature coefficient (NTC) thermistors.

espp/thermistor

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Thermistor Component

Example

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Supports all targets

Maintainer

License: MIT

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