mirror of
https://github.com/esphome/esphome-docs.git
synced 2024-11-05 09:20:08 +01:00
69 lines
2.2 KiB
ReStructuredText
69 lines
2.2 KiB
ReStructuredText
Resistance Sensor
|
|
=================
|
|
|
|
.. seo::
|
|
:description: Instructions for setting up resistance sensors in ESPHome
|
|
:image: omega.png
|
|
|
|
The ``resistance`` platform is a helper sensor that allows you to convert readings
|
|
from a voltage sensor (such as the :doc:`ADC Sensor <adc>`) into resistance readings
|
|
in Ω (ohm).
|
|
|
|
In order to calculate the resistance, the circuit needs to be set up in a
|
|
`voltage divider circuit <https://learn.sparkfun.com/tutorials/voltage-dividers/all>`__.
|
|
This consists of three parts:
|
|
|
|
- A voltage reference, usually this is connected to 3.3V (VCC). For example in the image
|
|
below it is 5V (though on ESPs you should not use that voltage)
|
|
- A reference resistor with constant resistance. For example below it is R₁ with a value
|
|
of 5.6kOhm.
|
|
- The variable resistor we wish the read the resistance of. Here R₂.
|
|
|
|
There are two kinds of configurations for this circuit: Either the variable resistor
|
|
is close to GND (DOWNSTREAM) or it is closer to VCC (UPSTREAM).
|
|
|
|
.. figure:: images/resistance-downstream.png
|
|
:align: center
|
|
:width: 25.0%
|
|
|
|
Example voltage divider configuration of type "DOWNSTREAM" and a voltage
|
|
reference of 5V.
|
|
|
|
.. code-block:: yaml
|
|
|
|
# Example configuration entry
|
|
sensor:
|
|
- platform: resistance
|
|
sensor: source_sensor
|
|
configuration: DOWNSTREAM
|
|
resistor: 5.6kOhm
|
|
name: Resistance Sensor
|
|
|
|
# Example source 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 voltage values from
|
|
to convert to resistance readings.
|
|
- **configuration** (**Required**, string): The type of circuit, one of ``DOWNSTREAM`` or
|
|
``UPSTREAM``.
|
|
- **resistor** (**Required**, float): The value of the resistor with a constant value.
|
|
|
|
- **reference_voltage** (*Optional*, float): The reference voltage. Defaults to ``3.3V``.
|
|
- **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:`ntc`
|
|
- :ref:`sensor-filters`
|
|
- :apiref:`resistance/resistance_sensor.h`
|
|
- :ghedit:`Edit`
|