Flash the device

With an external J-Link debugger attached to the Thingy:91 X, flash with the following command:

west flash --erase

The --erase option performs a full chip erase, including UICR, before programming. Without it, west flash fails with a UICR-related error when the new firmware writes different UICR contents.

By default, west flash after a sysbuild programs each bootloader and application image separately. That is equivalent to programming build/merged.hex, which combines the same images into one file. To generate the merged image and flash it in a single step, for example after changing the partition layout, use the following commands:

west ncs-mergehex --no-rebuild
west flash --erase --skip-rebuild --hex-file build/merged.hex

west ncs-mergehex combines the per-board-target build/merged_*.hex files from the sysbuild into build/merged.hex, as listed in app/mergehex.yaml.

Release builds publish the same merged image as asset-tracker-template-{VERSION}-<board>-nrf91.hex, as described in Release artifacts.

The Thingy:91 X does not have an on-board debugger. Flash over the serial bootloader using one of the following alternatives.

The first alternative, which Nordic Semiconductor recommends, is west thingy91x-dfu. It auto-discovers the device and flashes build/dfu_application.zip:

west thingy91x-dfu

The second alternative is nrfutil device program, which needs the Thingy:91 X serial number. To find the serial number, run nrfutil device list and locate the entry with Product: Thingy:91 X UART and the mcuBoot trait:

nrfutil device list

851006699
Product         J-Link
Traits          usb, jlink, seggerUsb

THINGY91X_ED0E7655C09       <-- this is the Thingy:91 X serial number
Product         Thingy:91 X UART
Ports           /dev/tty.usbmodem142102, vcom: 0
                /dev/tty.usbmodem142105, vcom: 1
Traits          mcuBoot, modem, serialPorts, nordicUsb, usb

Then flash, replacing <serial-number> with the identifier from the previous command (for example THINGY91X_ED0E7655C09):

nrfutil device program --firmware build/dfu_application.zip \
    --serial-number <serial-number> --traits mcuboot \
    --x-family nrf91 --core Application

To reset the Thingy:91 X from the terminal without re-flashing, which is equivalent to pressing the reset button, run the following command:

west thingy91x-reset