.. _i2c:

I²C Bus
=======

.. seo::
    :description: Instructions for setting up the I²C bus to communicate with 2-wire devices in ESPHome
    :image: i2c.png
    :keywords: i2c, iic, bus

This component sets up the I²C bus for your ESP32 or ESP8266. In order for those components
to work correctly, you need to define the I²C bus in your configuration. Please note the ESP
will enable its internal 10kΩ pullup resistors for these pins, so you usually don't need to
put on external ones.

.. code-block:: yaml

    # Example configuration entry
    i2c:
      sda: 21
      scl: 22
      scan: True
      id: bus_a

Configuration variables:
------------------------

- **sda** (*Optional*, :ref:`config-pin`): The pin for the data line of the I²C bus.
  Defaults to the default of your board (usually GPIO21 for ESP32 and GPIO4 for ESP8266).
- **scl** (*Optional*, :ref:`config-pin`): The pin for the clock line of the I²C bus.
  Defaults to the default of your board (usually GPIO22 for ESP32 and
  GPIO5 for ESP8266).
- **scan** (*Optional*, boolean): If ESPHome should do a search of the I²C address space on startup.
  Defaults to ``True``.
- **frequency** (*Optional*, float): Set the frequency the I²C bus should operate on.
  Defaults to ``50kHz``. Values are ``50kHz``, ``100kHz``, ``200kHz``, ... ``800kHz``
- **id** (*Optional*, :ref:`config-id`) Manually specify the ID for this I²C bus if you need multiple I²C buses.

.. note::

    If the device can support multiple I²C buses (ESP32 has 2) these buses need to be defined as below and sensors need to be setup specifying the correct bus:

    .. code-block:: yaml

        # Example configuration entry
        i2c:
          - id: bus_a
            sda: 13
            scl: 16
            scan: True
          - id: bus_b
            sda: 14
            scl: 15
            scan: True
       # Sensors should be specified as follows
       - platform: bme680
         i2c_id: bus_b
         address: 0x76
         # ...

See Also
--------

- :apiref:`i2c/i2c.h`
- :ghedit:`Edit`