esphome-docs/components/sensor/ntc.rst
2019-05-28 15:50:27 +02:00

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NTC Sensor
==========
.. seo::
:description: Instructions for setting up NTC thermistor sensor in ESPHome
:image: ntc.jpg
The ``ntc`` platform is a helper sensor that allows you to convert resistance readings
from a NTC thermistor to temperature readings.
First, you need to get resistance readings from the sensor - you can set this up with the
:doc:`resistance <resistance>` and :doc:`adc <adc>` sensors.
This platform will then convert the resistance values to temperature readings.
It also requires calibration parameters for this conversion. There are two
ways of obtaining these values: By looking at the datasheet or manual calculation.
If you have the datasheet of the thermistor, you can look at its "B-constant" and
reference temperature/resistance. For example `this product <https://www.adafruit.com/product/372>`__
would have the following calibration configuration.
.. code-block:: yaml
# Example configuration entry
sensor:
- platform: ntc
# ...
calibration:
b_constant: 3950
reference_temperature: 25°C
reference_resistance: 10kOhm
If you don't have access to the datasheet or want to calculate these values yourself,
you have to first measure three resistance values at different temperatures.
Heat/cool the NTC to three different temperatures (best if temperatures are far apart)
and write down the resistance readings at those temperatures. Then enter these values in the
calibration parameter:
.. code-block:: yaml
# Example configuration entry
sensor:
- platform: ntc
# ...
calibration:
- 10.0kOhm -> 25°C
- 27.219kOhm -> 0°C
- 14.674kOhm -> 15°C
.. code-block:: yaml
# Example configuration entry
sensor:
- platform: ntc
sensor: resistance_sensor
calibration:
b_constant: 3950
reference_temperature: 25°C
reference_resistance: 10kOhm
name: NTC Temperature
# Example source sensors:
- platform: resistance
id: resistance_sensor
sensor: source_sensor
configuration: DOWNSTREAM
resistor: 5.6kOhm
name: Resistance Sensor
- platform: adc
id: source_sensor
pin: A0
Configuration variables:
------------------------
- **name** (**Required**, string): The name for the sensor.
- **sensor** (**Required**, :ref:`config-id`): The sensor to read the resistance values from
to convert to temperature readings.
- **calibration** (**Required**, float): The calibration parameters of the sensor - see above
for more details.
- **id** (*Optional*, :ref:`config-id`): Set the ID of this sensor for use in lambdas.
- All other options from :ref:`Sensor <config-sensor>`.
See Also
--------
- :doc:`adc`
- :doc:`resistance`
- :ref:`sensor-filters`
- :apiref:`ntc/ntc.h`
- :ghedit:`Edit`