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119 lines
3.8 KiB
ReStructuredText
119 lines
3.8 KiB
ReStructuredText
SN74HC595 I/O Expander (shift register)
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=======================================
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.. seo::
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:description: Instructions for setting up SN74HC595 shift registers as digital port expanders in ESPHome.
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The SN74HC595 component allows you to use SN74HC595 shift registers as I/O expanders
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(`datasheet <http://www.ti.com/lit/ds/symlink/sn74hc595.pdf>`__,
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`SparkFun`_) in ESPHome. It uses 3 wires (optionally 4) for communication. Optionally, it can be added
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to a SPI bus to allow sharing pins with other components.
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Once configured, you can use any of the 8 pins for your projects. Up to 256 shift registers can be daisy-chained
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to provide more pins, without using more GPIO pins on the controller.
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Use of the OE pin is optional. If used, the pin should be pulled up externally.
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.. figure:: images/sn74hc595-full.jpg
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:align: center
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:width: 80.0%
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SN74HC595 I/O Expander (shift register).
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.. _SparkFun: https://www.sparkfun.com/products/13699
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The component can be configured using :ref:`GPIO pins <config-pin_schema>` or the :ref:`SPI Bus <spi>`.
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Over GPIO
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---------
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.. code-block:: yaml
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# Example configuration entry
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sn74hc595:
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- id: 'sn74hc595_hub'
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data_pin: D5
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clock_pin: D8
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latch_pin: D7
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oe_pin: D6
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sr_count: 2
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# Individual outputs
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switch:
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- platform: gpio
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name: "SN74HC595 Pin #0"
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pin:
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sn74hc595: sn74hc595_hub
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# Use pin number 0
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number: 0
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inverted: false
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Configuration variables:
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************************
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- **id** (**Required**, :ref:`config-id`): The id to use for this SN74HC595 component.
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- **data_pin** (**Required**, :ref:`Pin Schema <config-pin_schema>`): Pin connected to SN74HC595 SER (SD) input.
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- **clock_pin** (**Required**, :ref:`Pin Schema <config-pin_schema>`): Pin connected to SN74HC595 SRCLK (SH_CP) pin
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- **latch_pin** (**Required**, :ref:`Pin Schema <config-pin_schema>`): Pin connected to SN74HC595 RCLK (ST_CP) pin
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- **oe_pin** (*Optional*, :ref:`Pin Schema <config-pin_schema>`): Pin connected to SN74HC595 OE pin
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- **sr_count** (*Optional*, int): Number of daisy-chained shift registers, up-to 256. Defaults to ``1``.
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Pin configuration variables:
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****************************
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- **sn74hc595** (**Required**, :ref:`config-id`): The id of the SN74HC595 component the pin belongs to.
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- **number** (**Required**, int): The pin number.
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- **inverted** (*Optional*, boolean): If all written values should be treated as inverted.
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Defaults to ``false``.
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Over SPI
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--------
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.. code-block:: yaml
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# Example configuration entry
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spi:
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sn74hc595:
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- id: 'sn74hc595_hub'
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latch_pin: D7
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oe_pin: D6
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sr_count: 2
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# Individual outputs
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switch:
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- platform: gpio
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name: "SN74HC595 Pin #0"
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pin:
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sn74hc595: sn74hc595_hub
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# Use pin number 0
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number: 0
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inverted: false
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Configuration variables:
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************************
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- **id** (**Required**, :ref:`config-id`): The id to use for this SN74HC595 component.
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- **latch_pin** (**Required**, :ref:`Pin Schema <config-pin_schema>`): Pin connected to SN74HC595 RCLK (ST_CP) pin
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- **oe_pin** (*Optional*, :ref:`Pin Schema <config-pin_schema>`): Pin connected to SN74HC595 OE pin
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- **sr_count** (*Optional*, int): Number of daisy-chained shift registers, up to 256. Defaults to ``1``.
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Pin configuration variables:
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****************************
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- **sn74hc595** (**Required**, :ref:`config-id`): The id of the SN74HC595 component of the pin.
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- **number** (**Required**, int): The pin number.
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- **inverted** (*Optional*, boolean): If all written values should be treated as inverted.
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Defaults to ``false``.
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See Also
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--------
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- :doc:`switch/gpio`
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- :doc:`binary_sensor/gpio`
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- `Serial to Parallel Shifting-Out with a 74HC595 <https://www.arduino.cc/en/tutorial/ShiftOut>`__
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- :apiref:`sn74hc595/sn74hc595.h`
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- :ghedit:`Edit`
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