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Flashing via NXP uuu (Universal Update Utility)

Some i.MX-based boards support flashing via uuu (Universal Update Utility), NXP's USB-based download tool. This is useful for flashing eMMC without removing it from the board.

For board-specific hardware setup (boot switches, jumpers) see:

These boards build pv-flash-bundle as part of their release target list. It packages a portable uuu binary, the production imx-boot, the compressed WIC image, and a generated uuu.auto / flash.sh into a single self-contained archive — no separate uuu install or manual command needed on the host.

build/tmp-scarthgap/deploy/images/<machine>/pv-flash-bundle-<machine>.tar.gz
tar xzf pv-flash-bundle-<machine>.tar.gz
cd pv-flash-bundle-<machine>
./flash.sh

flash.sh decompresses the bundled WIC image (.wic.zst via zstd, or .wic.gz via zcat) and invokes sudo ./uuu ./, which reads uuu.auto and runs the full SDP → fastboot → eMMC flash sequence. Put the board into USB download mode first (see the board-specific page linked above) and connect USB before running it.

Variscite's production bootloader already self-enters SDP/fastboot download mode, so no separate recovery build is needed — unlike the Toradex boards, which use pv-flash-bundle with a recovery U-Boot.

Manual flashing (without pv-flash-bundle)​

Useful if you already have uuu installed and just want to reflash a WIC image without extracting a bundle.

Prerequisites​

  • USB Type-A to USB-C (or Micro-USB) cable connected to the board's USB OTG / download port
  • uuu installed on the host
# Install uuu on Debian/Ubuntu
sudo apt install uuu

# Or download the binary from GitHub releases

Locating the artifacts​

After a successful build, the WIC image and SPL/u-boot binaries are at:

build/tmp-scarthgap/deploy/images/<machine>/
  pantavisor-starter-<machine>*.wic
  imx-boot                      # SPL + u-boot FIT image (symlink)

Flashing procedure​

1. Put the board into USB download (serial download) mode​

See the board-specific page for the exact switch/jumper settings.

2. Connect USB and verify​

# uuu should detect the board
sudo uuu -lsusb

You should see an SDP: entry for the i.MX8M device listed.

3. Flash with uuu​

Option A — using the WIC image directly​
sudo uuu -b emmc_all imx-boot pantavisor-starter-<machine>*.wic
Option B — using a board-vendor uuu script (Variscite)​

Variscite BSPs ship a uuu_imx_android_flash.sh script. Refer to the Variscite wiki for the board-specific command.

4. Boot normally​

Remove the download-mode jumper/switch, then power-cycle the board. It will boot from eMMC.

Notes​

  • uuu requires root or udev rules granting access to the USB device. Add the NXP vendor udev rule if you get permission errors: 
    echo 'SUBSYSTEM=="usb", ATTR{idVendor}=="1fc9", MODE="0666"' \
        | sudo tee /etc/udev/rules.d/70-nxp-uuu.rules
    sudo udevadm control --reload-rules
  • The emmc built-in script writes only the bootloader; use emmc_all to write the full image. There is no built-in rootfs-only script.