.. _i2c-8x:

I2C
====

This guide will show you how to test the I2C interface on the phyCORE-i.MX8X development kit.

.. image:: ../../images/phycore-imx8x/pcm-065_i2c-callout.webp
  :width: 800px

.. note:: The phyCORE-i.MX8X SOM supports up to 9x I2C interfaces by default.

  Only four of these are supported on the phyCORE-i.MX8X carrier board and three of those four are reserved for specific interfaces (2x for the MIPI display 1x for the MIPI camera interfaces).


.. list-table:: I2C Paths
   :header-rows: 1

   * - Interface
     - Sysfs Path
   * - CSI0_I2C0
     - /dev/i2c-16
   * - DSI0_I2C0
     - /dev/i2c-17
   * - DSI1_I2C0
     - /dev/i2c-18
   * - I2C1
     - /dev/i2c-19


Using I2C1
------------

* Power on the development kit and boot into Linux.

* List the available I2C devices. There will be a few devices that pop up but /dev/i2c-19 corresponds to the I2C1 interface.

  .. code-block:: none
    :caption: Target (Linux)

    ls /dev/i2c*

  .. code-block:: none
    :caption: Expected Output

    /dev/i2c-16  /dev/i2c-17  /dev/i2c-18  /dev/i2c-19

* Use the "i2cdetect" command to scan the bus for devices. This command outputs the address of all devices on the I2C1 bus.

  .. note:: UU indicates that the device connected is tied to a kernel driver and you will be unable to communicate with the device via i2c commands (i2cset and i2cget).

.. code-block:: none
    :caption: Target (Linux)

    i2cdetect -y -r 16


.. code-block:: none
   :caption: Expected Output

          0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
     00: -- -- -- -- -- -- -- UU -- -- -- -- -- -- -- --
     10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
     20: UU -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
     30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 3f
     40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
     50: -- UU UU -- -- -- -- -- -- 59 -- -- -- -- -- --
     60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
     70: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --


The detected interfaces should match with the devices connected to I2C1 on the development kit.


.. list-table:: I2C Interface Addresses
   :header-rows: 1

   * - Interface
     - Address (7-bit
   * - GPIO Expander
     - 0x20
   * - USB-C Controller
     - 0x3F
   * - EEPROM
     - 0x51, 0x59
   * - RTC
     - 0x52
   * - Audio
     - 0x0A

.. note:: The EEPROM M24C32 has two different addresses (0x51 and 0x59) but one has been reserved in the device tree.