SenseAir S8 CO2 sensor support (#330)

* Docs

* CI fix

components/sensor/senseair.rst

@@ -0,0 +1,73 @@
+SenseAir CO_2 Sensor
+====================
+
+.. seo::
+    :description: Instructions for setting up SenseAir S8 CO2 sensor
+    :image: senseair_s8.jpg
+    :keywords: senseair_s8
+
+The ``senseair`` sensor platform allows you to use SenseAir CO_2 sensor
+(`website`_) with ESPHome.
+
+.. figure:: images/senseair_s8-full.jpg
+    :align: center
+    :width: 50.0%
+
+    SenseAir S8 CO_2 Sensor.
+
+.. _website: https://senseair.com/products/size-counts/senseair-s8-residential/
+
+As the communication with the SenseAir is done using UART, you need
+to have an :ref:`UART bus <uart>` in your configuration with the ``rx_pin`` connected to the TX pin of the
+sensor and the ``tx_pin`` connected to the RX Pin (it's switched because the
+TX/RX labels are from the perspective of the SenseAir sensor). Additionally, you need to set the baud rate to 9600.
+
+.. code-block:: yaml
+
+    # Example configuration entry
+    uart:
+      rx_pin: D0
+      tx_pin: D1
+      baud_rate: 9600
+
+    sensor:
+      - platform: senseair
+        co2:
+          name: "SenseAir CO2 Value"
+        update_interval: 60s
+
+Configuration variables:
+------------------------
+
+
+- **co2** (**Required**): The CO_2 data from the sensor in parts per million (ppm).
+
+  - **name** (**Required**, string): The name for the CO_2 sensor.
+  - **id** (*Optional*, :ref:`config-id`): Set the ID of this sensor for use in lambdas.
+  - All other options from :ref:`Sensor <config-sensor>`.
+
+- **update_interval** (*Optional*, :ref:`config-time`): The interval to check the
+  sensor. Defaults to ``60s``.
+
+- **uart_id** (*Optional*, :ref:`config-id`): Manually specify the ID of the :ref:`UART Component <uart>` if you want
+  to use multiple UART buses.
+
+- **id** (*Optional*, :ref:`config-id`): Manually specify the ID used for actions.
+
+.. figure:: images/senseair_s8-pins.jpg
+    :align: center
+    :width: 80.0%
+
+    Pins on the SenseAir S8. Only the ones marked with a red circle need to be connected.
+
+.. note::
+
+    ``G+`` should be connected to power supply (supported voltage is 4.5 V to 5.25 V), ``G0`` to ``GND`` pin
+
+
+See Also
+--------
+
+- :ref:`sensor-filters`
+- :apiref:`senseair/senseair.h`
+- :ghedit:`Edit`

index.rst

@@ -129,6 +129,7 @@ Sensor Components
     Pulse Width, components/sensor/pulse_width, pulse.svg
     Resistance, components/sensor/resistance, omega.svg
     Rotary Encoder, components/sensor/rotary_encoder, rotary_encoder.jpg
+    SenseAir, components/sensor/senseair, senseair_s8.jpg
     SDS011 Sensor, components/sensor/sds011, sds011.jpg
     SCD30, components/sensor/scd30, scd30.jpg
     SHT3X-D, components/sensor/sht3xd, sht3xd.jpg