Add PCA9554 docs (#2532)

components/pca9554.rst

@@ -0,0 +1,83 @@
+PCA9554 I/O Expander
+====================
+
+The PCA9554 component allows you to use PCA9554, PCA9554A or PCA9536 I/O expanders
+(`PCA9554 datasheet <https://www.ti.com/lit/ds/symlink/pca9554.pdf>`__, 
+`PCA9554A datasheet <https://www.ti.com/lit/ds/symlink/pca9554a.pdf>`__, 
+`PCA9536 datasheet <https://www.ti.com/lit/ds/symlink/pca9536.pdf>`__) in ESPHome. 
+It uses :ref:`I²C Bus <i2c>` for communication.
+
+Once configured, you can use any of the 8 pins (PCA9554, PCA9554A) or 4 pins (PCA9536) as
+pins for your projects. Within ESPHome they emulate a real internal GPIO pin
+and can therefore be used with many of ESPHome's components such as the GPIO
+binary sensor or GPIO switch.
+
+The 7 bit I2C device address ranges are:
+
+PCA9554   : 0x20 to 0x27
+
+PCA9554A  : 0x38 to 0x3F
+
+PCA9536   : 0x41
+
+For the PCA9554 and PCA9554A, the actual choice of the I2C device address depends on state of the 3 address pins.
+Please refer to the individual datasheets for further details.
+
+Up to eight PCA9554 and an additional eight PCA9554A devices can reside on the same I2C bus. 
+Please note that only one PCA9536 device is allowed per I2C bus due to its fixed address.
+
+The PCA9554 and PCA9554A provide 8 bits of GPIO's (pin numbers 0-7)
+The PCA9536 provides 4 bits of GPIO's (pin numbers 0-3).
+
+Any option accepting a :ref:`Pin Schema <config-pin_schema>` can theoretically be used, but some more
+complicated components that do communication through this I/O expander will
+not work.
+
+.. code-block:: yaml
+
+    # Example configuration entry
+    pca9554:
+      - id: 'pca9554a_device'
+        address: 0x38
+      
+
+    # Individual outputs
+    switch:
+      - platform: gpio
+        name: "PCF9554A Pin #0"
+        pin:
+          pca9554: pcf9554a_device
+          # Use pin number 0
+          number: 0
+          # One of INPUT or OUTPUT
+          mode:
+            output: true
+          inverted: false
+
+Configuration variables:
+************************
+
+- **id** (**Required**, :ref:`config-id`): The id to use for this PCF9554 component.
+- **address** (*Optional*, int): The I²C address of the driver.
+  Defaults to ``0x20``.
+
+
+
+Pin configuration variables:
+****************************
+
+- **pca9554** (**Required**, :ref:`config-id`): The id of the PCA9554 component of the pin.
+- **number** (**Required**, int): The pin number.
+- **inverted** (*Optional*, boolean): If all read and written values
+  should be treated as inverted. Defaults to ``false``.
+- **mode** (*Optional*, string): A pin mode to set for the pin at. One of ``INPUT`` or ``OUTPUT``.
+
+
+See Also
+--------
+
+- :ref:`i2c`
+- :doc:`switch/gpio`
+- :doc:`binary_sensor/gpio`
+- :apiref:`pca9554/pca9554.h`
+- :ghedit:`Edit`

index.rst

@@ -675,6 +675,7 @@ Misc Components
     Servo, components/servo, servo.svg
     Sprinkler, components/sprinkler, sprinkler-variant.svg
 
+    PCA9554 I/O Expander, components/pca9554, pca9554a.jpg
     PCF8574 I/O Expander, components/pcf8574, pcf8574.jpg
     MCP230XX I/O Expander - I²C Bus, components/mcp230xx, mcp230xx.svg
     TCA9548A I²C Multiplexer, components/tca9548a, tca9548a.jpg