Add CST816 touchscreen docs (#3459)

* Add CST816 touchscreen docs


---------

Co-authored-by: H. Árkosi Róbert <robreg@zsurob.hu>

components/touchscreen/cst816.rst

@@ -0,0 +1,69 @@
+cst816 Touch Screen Controller
+===============================
+
+.. seo::
+    :description: Instructions for setting up cst816 touch screen controller with ESPHome
+    :image: cst816.jpg
+    :keywords: CST816, T-DISPLAY, AMOLED
+
+The ``cst816`` touchscreen platform allows using the touch screen controllers based on the CST816 series of chips with ESPHome.
+The :ref:`I²C <i2c>` is required to be set up in your configuration for this touchscreen to work.
+
+This controller is used in the Lilygo T-Display S3 AMOLED. The component should work with CST816T, CST816S, CST820 and CST716
+controller chips.
+
+
+.. figure:: images/cst816.jpg
+    :align: center
+    :width: 50.0%
+
+    cst816t touchscreen on T-Display S3 AMOLED
+
+Base Touchscreen Configuration
+------------------------------
+
+.. code-block:: yaml
+
+    # Example configuration entry
+    touchscreen:
+      platform: cst816
+      id: my_touchscreen
+      interrupt_pin: GPIO3
+      reset_pin: GPIO21
+
+Configuration variables:
+************************
+
+- **id** (*Optional*, :ref:`config-id`): Manually set the ID of this touchscreen.
+- **interrupt_pin** (*Optional*, :ref:`Pin Schema <config-pin_schema>`): The touch detection pin.
+- **reset_pin** (**Optional**, :ref:`Pin Schema <config-pin_schema>`): The chip reset pin.
+
+- All other options from :ref:`Touchscreen <config-touchscreen>`.
+
+Binary Sensor
+-------------
+
+In addition to touch areas on the screen configured through the :ref:`Touchscreen <config-touchscreen>` component,
+the cst816 will report touches on a button outside the screen area.
+A binary sensor can be configured to react to touching this button.
+
+.. code-block:: yaml
+
+    # Example configuration entry
+    binary_sensor:
+      - platform: cst816
+        name: "Home"
+
+Configuration variables:
+************************
+
+- **cst816_id** (*Optional*, :ref:`config-id`): Manually specify the ID of the touchscreen.
+
+- All other options from :ref:`Binary Sensor <config-binary_sensor>`.
+
+
+See Also
+--------
+
+- :apiref:`cst816/touchscreen/cst816_touchscreen.h`
+- :ghedit:`Edit`

index.rst

@@ -693,6 +693,7 @@ Touchscreen Components
 .. imgtable::
 
     Touchscreen Core, components/touchscreen/index, folder-open.svg, dark-invert
+    CST816, components/touchscreen/cst816, cst816.jpg
     EKTF2232, components/touchscreen/ektf2232, ektf2232.svg, Inkplate 6 Plus
     Lilygo T5 4.7", components/touchscreen/lilygo_t5_47, lilygo_t5_47_touch.jpg
     TT21100, components/touchscreen/tt21100, esp32-s3-korvo-2-lcd.png