101 lines
3.3 KiB
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101 lines
3.3 KiB
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Analog To Digital Sensor
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========================
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.. seo::
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:description: Instructions for setting up built-in analog voltage sensors.
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:image: flash.svg
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The Analog To Digital (``adc``) Sensor allows you to use the built-in
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ADC in your device to measure a voltage on certain pins. On the ESP8266
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only pin A0 (GPIO17) supports this. On the ESP32 pins GPIO32 through
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GPIO39 can be used.
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.. figure:: images/adc-ui.png
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:align: center
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:width: 80.0%
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.. code:: yaml
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# Example configuration entry
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sensor:
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- platform: adc
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pin: A0
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name: "Living Room Brightness"
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update_interval: 15s
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Configuration variables:
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------------------------
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- **pin** (**Required**, :ref:`config-pin`): The pin to measure the voltage on.
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Or on the ESP8266 alternatively also ``VCC``, see :ref:`adc-esp8266_vcc`.
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- **name** (**Required**, string): The name of the voltage sensor.
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- **attenuation** (*Optional*): Only on ESP32. Specify the ADC
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attenuation to use. See :ref:`adc-esp32_attenuation`.
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- **update_interval** (*Optional*, :ref:`config-time`): The interval
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to check the sensor. Defaults to ``15s``. See :ref:`sensor-default_filter`.
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- **id** (*Optional*, :ref:`config-id`): Manually specify the ID used for code generation.
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- All other options from :ref:`Sensor <config-sensor>` and :ref:`MQTT Component <config-mqtt-component>`.
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.. note::
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On the ESP8266, the voltage range is 0 to 1.0V - so to measure any higher voltage you need to scale the voltage
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down using, for example, a voltage divider circuit.
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.. _adc-esp32_attenuation:
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ESP32 Attenuation
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-----------------
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On the ESP32, the voltage measured with the ADC caps out at 1.1V by default as the sensing range
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or the attenuation of the ADC is set to ``0db`` by default.
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To measure voltages higher than 1.1V, set ``attenuation`` to one of the `following values
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<http://esp-idf.readthedocs.io/en/latest/api-reference/peripherals/adc.html#_CPPv225adc1_config_channel_atten14adc1_channel_t11adc_atten_t>`__:
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- ``0db`` for a full-scale voltage of 1.1V (default)
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- ``2.5db`` for a full-scale voltage of 1.5V
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- ``6db`` for a full-scale voltage of 2.2V
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- ``11db`` for a full-scale voltage of 3.9V
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.. _adc-esp8266_vcc:
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ESP8266 Measuring VCC
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---------------------
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On the ESP8266 you can even measure the voltage the chip is getting. This can be useful in situations
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where you want to shut down the chip if the voltage is low when using a battery.
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To measure the VCC voltage, set ``pin:`` to ``VCC`` and make sure nothing is connected to the ``A0`` pin.
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.. code:: yaml
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sensor:
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- platform: adc
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pin: VCC
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name: "VCC Voltage"
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Next, you need to add a line at the top of your C++ project source code. Unfortunately, esphomelib can't do this
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automatically for you because of how the compiler is linking the esphomelib library. Open up the
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``<NODE_NAME>/src/main.cpp`` file and insert the ``ADC_MODE`` line like this:
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.. code:: cpp
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using namespace esphomelib;
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// Enable measuring VCC
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ADC_MODE(ADC_VCC);
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void setup() {
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// ...
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See Also
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--------
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- :ref:`sensor-filters`
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- :doc:`ads1115`
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- :doc:`max6675`
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- :doc:`API Reference </api/sensor/adc>`
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- `Edit this page on GitHub <https://github.com/OttoWinter/esphomedocs/blob/current/esphomeyaml/components/sensor/adc.rst>`__
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.. disqus::
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