Entering single-Bank Device Firmware Update (DFU) mode
nRF Connect SDK Bare Metal option supports a single-bank DFU mechanism. The device normally executes the application that cannot update itself nor the firmware elements it depends on. This means that the device running the application must be switched to the DFU mode so that it can run the firmware loader. The firmware loader is a physically separated firmware entity that provides services for supporting the firmware download to the single bank. Decision on entering the firmware loader is made by the MCUboot. The available entering schemes are listed the following sections.
Entering on GPIO state
The firmware loader is entered when the active state of a GPIO pin is asserted during early device startup.
The SoC must be rebooted, for instance, by the board power toggling to perform this action.
Use the SB_CONFIG_BM_BOOTLOADER_MCUBOOT_FIRMWARE_LOADER_ENTRANCE_GPIO sysbuild Kconfig option to enter this mode.
The GPIO PIN is configured by the defining BOARD_PIN_BTN_0 of the board in its include/board-config.h file.
Entering on reset by PIN
The firmware loader is entered when the SoC reset is triggered by the reset pin.
Use the SB_CONFIG_BM_BOOTLOADER_MCUBOOT_FIRMWARE_LOADER_ENTRANCE_PIN_RESET sysbuild Kconfig option to enter this mode.