75 lines
2.7 KiB
ReStructuredText
75 lines
2.7 KiB
ReStructuredText
.. _i2c:
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I²C Bus
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=======
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.. seo::
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:description: Instructions for setting up the I²C bus to communicate with 2-wire devices in ESPHome
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:image: i2c.svg
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:keywords: i2c, iic, bus
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This component sets up the I²C bus for your ESP32 or ESP8266. In order for these components
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to work correctly, you need to define the I²C bus in your configuration. Please note the ESP
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will enable its internal 10kΩ pullup resistors for these pins, so you usually don't need to
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put on external ones. You can use multiple devices on one I²C bus as each device is given a
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unique address for communicating between it and the ESP. You can do this by hopping
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wires from the two lines (SDA and SCL) from each device board to the next device board or by
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connecting the wires from each device back to the two I²C pins on the ESP.
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.. code-block:: yaml
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# Example configuration entry for ESP32
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i2c:
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sda: 21
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scl: 22
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scan: true
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id: bus_a
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Configuration variables:
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------------------------
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- **sda** (*Optional*, :ref:`config-pin`): The pin for the data line of the I²C bus.
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Defaults to the default of your board (usually GPIO21 for ESP32 and GPIO4 for ESP8266).
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- **scl** (*Optional*, :ref:`config-pin`): The pin for the clock line of the I²C bus.
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Defaults to the default of your board (usually GPIO22 for ESP32 and
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GPIO5 for ESP8266).
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- **scan** (*Optional*, boolean): If ESPHome should do a search of the I²C address space on startup.
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Defaults to ``true``.
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- **frequency** (*Optional*, float): Set the frequency the I²C bus should operate on.
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Defaults to ``50kHz``. Values are ``10kHz``, ``50kHz``, ``100kHz``, ``200kHz``, ... ``800kHz``
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- **timeout** (*Optional*, :ref:`config-time`): Set the I²C bus timeout.
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Defaults to the framework defaults (``100us`` on ``esp32`` with ``esp-idf``, ``50ms`` on ``esp32`` with ``Arduino``,
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``1s`` on ``esp8266`` and ``1s`` on ``rp2040``). Maximum on ``esp-idf`` is 13ms.
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- **id** (*Optional*, :ref:`config-id`): Manually specify the ID for this I²C bus if you need multiple I²C buses.
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.. note::
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If the device can support multiple I²C buses (ESP32 has 2, ESP8266 does not support more than one) these buses need to be defined as below and sensors need to be setup specifying the correct bus:
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.. code-block:: yaml
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# Example configuration entry
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i2c:
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- id: bus_a
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sda: 13
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scl: 16
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scan: true
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- id: bus_b
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sda: 14
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scl: 15
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scan: true
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# Sensors should be specified as follows
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- platform: bme680
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i2c_id: bus_b
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address: 0x76
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# ...
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For I2C multiplexing see :doc:`/components/tca9548a`.
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See Also
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--------
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- :doc:`/components/tca9548a`
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- :apiref:`i2c/i2c.h`
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- :ghedit:`Edit`
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