SPI
====

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

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

Requirements
--------------

* Female to Female Jumper Wire (1x)

* SDHC SD card, at least 8GB for PHYTEC’s TISDK release image (Included in development kit)

* Linux Host PC or Virtual Machine (Ubuntu recommended) (Only for Transfering Media from Host)

* SD card reader (operational under Linux) (Only for Transfering Media from Host)

Hardware Setup
---------------

* Connect pins 4 and 5 of X94 using a F-F jumper wire. These pins correspond to SPI3's MISO and MOSI signals

  .. image:: ../../images/phycore-imx8x/pcm-065_spi-closeup.webp
    :width: 500px

* Add the following file into the root directory of the file system that you are booting from.

   :download:`spidev_test <../../files/general/spidev_test>`

* SD Card "root" Partition Using Ubuntu

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

    sudo cp spidev_test /media/user/root/home/root/

* Plug the SD Card into your development kit, power on, and boot into Linux.

* Initiate the loop-back test on the SPI3 interface (/dev/spidev1.0)

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

    ./spidev_test -v -D /dev/spidev1.0

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

    spi mode: 0x0
    bits per word: 8
    max speed: 500000 Hz (500 KHz)
    TX | FF FF FF FF FF FF 40 00 00 00 00 95 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF F0 0D  |......@.........................|
    RX | FF FF FF FF FF FF 40 00 00 00 00 95 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF F0 0D  |......@.........................|

 .. note:: If SPI communication is not functioning properly, only "00"s will be printed in the "rx data".

           This can be demonstrated by running the previous command again with the wire removed.