.. include:: ../substitutions.rst

SPI
===

The Serial Peripheral Interface (SPI) is a transmit/receive, master/slave synchronous serial bus. The |product| SOM provides access to |intf-spi-interfaces| SPI ports at the phyCORE-Connector. This guide will show you how to test the SPI interface on the |product| development kit carrier board via a loopback test. To learn more information about the |product| SPI, please see section |hw-ref-spi| in the |hw-manual-link|.

.. jinja::
   :file: ../templates/interfaceguides/spi-intro.jinja

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

* Jumper Wire Male to Male


Development Kit Setup
---------------------

.. jinja::
   :file: ../templates/interfaceguides/spi-dev-kit-setup.jinja


Loop-back Test
--------------

* Initiate the loop-back test on the SPI |intf-spi-interface-number| interface (/dev/spidev |intf-spi-spidev-number|)

  .. code-block:: console
     :substitutions:

     |target-prompt| spidev_test -v -D /dev/spidev|intf-spi-spidev-number|
     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 or "FF"s will be printed in the "rx data".

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