Fastboot is a protocol for communication between your device and a computer. It allows you to modify file system images over a USB connection, which is a quick way to update firmware during development. Fastboot requires the USB interface to work as 'device'.

Although it was originally developed for Android images, its implementation on the NXP UUU (Universal Update Utility) tool extends the functionality to any file type.

To update U-Boot via USB OTG using uuu and the Fastboot protocol:

  1. Download the latest Universal Update Utility (UUU) tool, a software tool from NXP.

  2. Place the uuu executable in a directory in your PATH, such as /usr/bin.

  3. Install udev rules to allow any user to run the uuu for accessing the USB port:

    ~$ sudo sh -c "uuu -udev >> /etc/udev/rules.d/99-uuu.rules"
    ~$ sudo udevadm control --reload-rules
  4. Connect a USB type-C cable to your development PC and the other end to the target USB type-C connector.

  5. Reset the device by pressing the reset button on the board and immediately press any key in the serial terminal to stop the auto-boot process. The U-Boot bootloader prompt displays:

    U-Boot dub-2020.04-r2.2 (Jan 18 2021 - 15:54:04 +0000)
    
    CPU:   NXP i.MX8QXP RevB A35 at 1200 MHz at 25C
    DRAM:  2 GiB
    MCA:   HW_VER=1  FW_VER=1.01
    MMC:   FSL_SDHC: 0, FSL_SDHC: 1
    In:    serial
    Out:   serial
    Err:   serial
    Model: Digi International ConnectCore 8X SBC Pro Board.
    ConnectCore 8X SOM variant 0x02: 2 GiB LPDDR4, Wi-Fi, Bluetooth, MCA, Crypto-auth
      Board version 3, ID 135
    Boot:  MMC0
    
     BuildInfo:
      - SCFW 56682d58, SECO-FW 0e4b9cee, IMX-MKIMAGE 8da5cd23, ATF c949a88
      - U-Boot dub-2020.04-r2.2
    
    flash target is MMC:0
    Net:   eth0: ethernet@5b040000 [PRIME], eth1: ethernet@5b050000
    Fastboot: Normal
    Normal Boot
    Hit any key to stop autoboot:  0
    =>
    Information in the console log may vary.
  6. On the target, in U-Boot, execute the following command:

    => fastboot 1
  7. On your development PC, change to your Digi Embedded Yocto project’s deploy images folder and execute the following command:

    ~$ cd tmp/deploy/images/ccimx8x-sbc-pro/
    ~$ ./install_linux_fw_uuu.sh

    These instructions assume that the target U-Boot version is v2019.04 or higher. For U-Boot v2018.03 or lower, you must pass the U-Boot filename as an argument depending on your ConnectCore 8X variant. See U-Boot files by variant:

    ~$ ./install_linux_fw_uuu.sh <u-boot-file>
  8. Once the firmware is installed, the device boots automatically. The default username is root with no password.