SPI

The Serial Peripheral Interface (SPI) is a transmit/receive, master/slave synchronous serial bus. The phyCORE-AM62x SOM provides access to four SPI ports at the phyCORE-Connector. This guide will show you how to test the SPI interface on the phyCORE-AM62x development kit carrier board via a loopback test. To learn more information about the phyCORE-AM62x SPI, please see section 7.4 in the Hardware Manual.

phyCORE-AM62x SPI

Requirements

  • M/M Jumper Wire

    Note

    The expansion header was designed for 2mm pins. It is acceptable to use 2.54mm jumper pins during the development and verification of interfaces. The only issue arises when you switch back to plugging in a 2mm male header for an expansion board you created.

Development Kit Setup

Note

There are 2x SPI interfaces on the phyCORE-AM62x SOM but only one is set up for use on the development kit carrier board (SPI0).

In the software, the SPI0 interface can be accessed through /dev/spidev3.0

  • Power off and remove the power supply from the development kit.

    Target (Linux)
      poweroff

  • Connect pin 40 and pin 42 of X17 using a M-M jumper wire. These pins correspond to SPI0’s MISO and MOSI signals.

Enabling Overlay & Script

  • Power on the board and press any key to stop autoboot and enter U-Boot.

  • Type the following commands to enable the device tree overlay:

    Target (U-Boot)
     setenv overlays k3-am62-phyboard-lyra-x17-spi0.dtbo
 boot

Loop-back Test

  • Initiate the loop-back test on the SPI0 interface (/dev/spidev1.0)

    Target (Linux)
    spidev_test -v -D /dev/spidev1.0
    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 or “FF”s will be printed in the “rx data”.

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