PCF8574 I/O Expander
====================

The PCF8574 component allows you to use PCF8574 or PCF8575 I/O expanders
(`datasheet <http://www.ti.com/lit/ds/symlink/pcf8574.pdf>`__,
`Sparkfun`_) in esphomeyaml. It
uses `I²C Bus </esphomeyaml/components/i2c.html>`__ for communication.

Once configured, you can use any of the 8 pins (PCF8574) or 16 pins (PCF8575) as
pins for your projects. Within esphomelib they emulate a real internal GPIO pin
and can therefore be used with many of esphomelib's components such as the GPIO
binary sensor or GPIO switch.

Any option accepting a `Pin Schema`_ can theoretically be used, but some more
complicated components that do communication through this I/O expander will
not work.

.. figure:: /esphomeyaml/components/pcf8574-full.jpg
   :align: center
   :target: `Sparkfun`_
   :width: 50.0%

   PCF8574 I/O Expander. Image by `Sparkfun`_.

.. _Sparkfun: https://www.sparkfun.com/products/retired/8130

.. code:: yaml

    # Example configuration entry
    pcf8574:
      - id: 'pcf8574_hub'
        address: 0x21
        pcf8575: False

    # Individual outputs
    switch:
      - platform: gpio
        name: "PCF8574 Pin #0"
        pin:
          pcf8574: pcf8574_hub
          # Use pin number 0
          number: 0
          # One of INPUT, INPUT_PULLUP or OUTPUT
          mode: INPUT
          inverted: False

Configuration variables:
~~~~~~~~~~~~~~~~~~~~~~~~

-  **id** (**Required**,
   `id </esphomeyaml/configuration-types.html#id>`__): The id to use for
   this PCF8574 component.
-  **address** (*Optional*, int): The I²C address of the driver.
   Defaults to ``0x21``.
-  **pcf8575** (*Optional*, boolean): Whether this is a 16-pin PCF8575. Defaults to
   ``False``.

.. _Pin Schema: /esphomeyaml/configuration-types.html#pin-schema