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[ADC] Reference new "raw output" option + clarify voltage ranges (#1592)

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Carlos Garcia Saura 2021-11-10 19:13:16 +01:00 committed by GitHub
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components/sensor/adc.rst
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@ -30,7 +30,8 @@ Configuration variables:
Or on the ESP8266 alternatively also ``VCC``, see :ref:`adc-esp8266_vcc`.
- **name** (**Required**, string): The name of the voltage sensor.
- **attenuation** (*Optional*): Only on ESP32. Specify the ADC
attenuation to use. See :ref:`adc-esp32_attenuation`.
attenuation to use. See :ref:`adc-esp32_attenuation`. Defaults to ``0db``.
- **raw** (*Optional*): Allows to read the raw ADC output without any conversion or calibration. Defaults to ``false``.
- **update_interval** (*Optional*, :ref:`config-time`): The interval
to check the sensor. Defaults to ``60s``.
- **id** (*Optional*, :ref:`config-id`): Manually specify the ID used for code generation.
@ -52,23 +53,23 @@ Configuration variables:
- multiply: 3.3
.. _adc-esp32_attenuation:
ESP32 Attenuation
-----------------
On the ESP32, the voltage measured with the ADC caps out at 1.1V by default as the sensing range
or the attenuation of the ADC is set to ``0db`` by default.
On the ESP32 the voltage measured with the ADC caps out at ~1.1V by default as the sensing range (attenuation of the ADC) is set to ``0db`` by default.
Measuring higher voltages requires setting ``attenuation`` to one of the following values: ``0db``, ``2.5db``, ``6db``, ``11db``.
There's more information `at the manufacturer's website <https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-reference/peripherals/adc.html#_CPPv425adc1_config_channel_atten14adc1_channel_t11adc_atten_t>`__.
To measure voltages higher than 1.1V, set ``attenuation`` to one of the `following values
<https://docs.espressif.com/projects/esp-idf/en/latest/api-reference/peripherals/adc.html#_CPPv225adc1_config_channel_atten14adc1_channel_t11adc_atten_t>`__:
To simplify this, we provide the setting ``attenuation: auto`` for an automatic/seamless transition among scales. `Our implementation
<https://github.com/esphome/esphome/blob/dev/esphome/components/adc/adc_sensor.cpp>`__ combines all available ranges to allow the best resolution without having to compromise on a specific attenuation.
.. note::
In our tests, the usable ADC range was from ~0.075V to ~3.12V (with the ``attenuation: auto`` setting), and anything outside that range capped out at either end.
Even though the measurements are calibrated, the range *limits* are variable among chips due to differences in the internal voltage reference.
- ``0db`` for a full-scale voltage of 1.1V (default)
- ``2.5db`` for a full-scale voltage of 1.5V
- ``6db`` for a full-scale voltage of 2.2V
- ``11db`` for a full-scale voltage of 3.9V
- ``auto`` for an automatic/seamless transition among scales
.. _adc-esp8266_vcc: