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95 lines
3.0 KiB
ReStructuredText
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.png
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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-block:: 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: 60s
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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 ``60s``.
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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>`.
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.. note::
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This component prints the voltage as seen by the chip pin. On the ESP8266, this is always 0.0V to 1.0V
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Some development boards like the Wemos D1 mini include external voltage divider circuitry to scale down
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a 3.3V input signal to the chip-internal 1.0V. If your board has this circuitry, add a multiply filter to
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get correct values:
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.. code-block:: yaml
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sensor:
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- platform: adc
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# ...
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filters:
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- multiply: 3.3
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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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<https://docs.espressif.com/projects/esp-idf/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-block:: 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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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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- :apiref:`adc/adc_sensor.h`
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- :ghedit:`Edit`
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