add person sensor (sen21231) from useful sensors (#2678)

Co-authored-by: Jesse Hills <3060199+jesserockz@users.noreply.github.com>

components/sensor/sen21231.rst

@@ -0,0 +1,36 @@
+SEN21231 Person Sensor from Useful Sensors
+==========================================
+
+.. seo::
+    :description: Instructions for setting up a SEN21231 Person Sensor from Useful Sensors with ESPHome.
+    :image: description.svg
+
+`Person Sensor (SEN21231) from Useful Sensors <https://usefulsensors.com/person-sensor>`__ has built in facial recognition that can detect how many people are facing the sensor and relative positions of the faces.
+
+.. figure:: images/sen21231.png
+    :align: center
+    :width: 70.0%
+
+
+    Person Sensor
+
+This sensor requires an :doc:`/components/i2c`. The I2C address is ``0x62``
+
+.. code-block:: yaml
+
+    # Example configuration entry
+    sensor:
+      - platform: sen21231
+        id: person_sensor
+
+Configuration variables:
+------------------------
+
+- All options from :ref:`Sensor <config-sensor>`.
+
+See Also
+--------
+
+- :doc:`/components/sensor/index`
+- :apiref:`sen21231/sen21231.h`
+- :ghedit:`Edit`

index.rst

@@ -361,6 +361,7 @@ Miscellaneous
     uFire EC sensor, components/sensor/ufire_ec, ufire_ec.png, EC & Temperature
     uFire ISE sensor, components/sensor/ufire_ise, ufire_ise.png, pH & Temperature
     Resol VBus, components/vbus, resol_deltasol_bs_plus.jpg
+    Person Sensor (SEN21231), components/sensor/sen21231, sen21231.png
 
 
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