CCS811 eCO_2 and Volatile Organic Compound Sensor
=================================================

.. seo::
    :description: Instructions for setting up CCS811 sensors.
    :image: ccs811.jpg

The ``ccs811`` sensor platform allows you to use CCS811 eCO_2 and volatile organic compound sensors
(`Adafruit`_) with ESPHome.

.. note::

    Most CCS811 modules require the WAK pin to be pulled low to wake up the sensor, as outlined in the data sheets.
    Outside low-power scenarios, connecting WAK to ground is the recommended configuration. For low power installations,
    pulling WAK low should happen in software prior to taking the measures.

.. figure:: images/ccs811-full.jpg
    :align: center
    :width: 50.0%

    CCS811 Sensor. Image by `Adafruit`_

.. _Adafruit: https://www.adafruit.com/product/3566

The communication with this sensor is done via :ref:`I²C Bus <i2c>`, so you need to have
an ``i2c:`` section in your config for this component to work.

.. code-block:: yaml

    # Example configuration entry
    i2c:
      sda: D0
      scl: D1

    sensor:
      - platform: ccs811
        eco2:
          name: "CCS811 eCO2 Value"
        tvoc:
          name: "CCS811 Total Volatile Organic Compound"
        address: 0x5A
        update_interval: 60s

Configuration variables:
------------------------

- **eco2** (**Required**): The eCO_2 data from the sensor in parts per million (ppm).

  - All options from :ref:`Sensor <config-sensor>`.

- **tvoc** (**Required**): The information for the total volatile organic compound sensor in
  parts per billion (ppb).

  - All options from :ref:`Sensor <config-sensor>`.

- **update_interval** (*Optional*, :ref:`config-time`): The interval to check the
  sensor. Defaults to ``60s``.

- **version** (*Optional*): This sensor reports the firmware ('application') version in text, with the internal hex representation of the version number behind it, so version 1.0.0 will be reported as '1.0.0 (0x1000)'.

  - All options from :ref:`Text Sensor <config-text_sensor>`.

Advanced:

- **address** (*Optional*, int): The :ref:`I²C <i2c>` address of the sensor.

- **baseline** (*Optional*, int): The baseline value for the unit, for calibration
  purposes. See :ref:`ccs811-calibrating` for more info.

- **temperature** (*Optional*, :ref:`config-id`): Give an external temperature sensor ID
  here. This can improve the sensor's internal calculations.
- **humidity** (*Optional*, :ref:`config-id`): Give an external humidity sensor ID
  here. This can improve the sensor's internal calculations.

.. _ccs811-calibrating:

Calibrating Baseline
--------------------

The CCS811 sensor will re-calibrate itself each time it is powered on. Unfortunately
that also means that if the sensor reboots at a time when the air is less clean than normal,
the values will have a constant offset and cannot be compared to the values before the last
boot.

To have consistent values, you need to specify a static **baseline** value (the calibration factor).
To do this, first let the sensor boot up with no baseline set and let the sensor calibrate
itself. After around 20-30 minutes you can then view the remote logs on the ESP. The next
time the sensor is read out, you will see a log message with something like ``baseline=0xA483``.

Now set the baseline property in your configuration file like so with the value you got
via the logs:

.. code-block:: yaml

    # Example configuration entry
    sensor:
      - platform: ccs811
        # ...
        baseline: 0xA483

The next time you upload the code, the CCS811 will be informed of this static baseline
and you will get consistent values.

Please note that after some time (a couple of months), the baseline will need to be
re-calibrated because the internal sensor has a slight value drift over time.

See Also
--------

- :ref:`sensor-filters`
- `CCS811 Application Note <https://cdn.sparkfun.com/datasheets/BreakoutBoards/CCS811_Programming_Guide.pdf>`__
- :apiref:`ccs811/ccs811.h`
- :ghedit:`Edit`