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Device Firmware Upgrade

Overview

The Device Firmware Upgrade subsystem provides the necessary frameworks to upgrade the image of a Zephyr-based application at run time. It currently consists of two different modules:

subsys/dfu/boot/: Interface code to bootloaders
subsys/dfu/img_util/: Image management code

The DFU subsystem deals with image management, but not with the transport or management protocols themselves required to send the image to the target device. For information on these protocols and frameworks please refer to the Device Management section.

Flash Image

The flash image API as part of the Device Firmware Upgrade (DFU) subsystem provides an abstraction on top of Flash Stream to simplify writing firmware image chunks to flash.

API Reference

Flash image API

MCUBoot API

The MCUboot API is provided to get version information and boot status of application images. It allows to select application image and boot type for the next boot.

API Reference

MCUboot image control API

Bootloaders

MCUboot

Zephyr is directly compatible with the open source, cross-RTOS MCUboot boot loader. It interfaces with MCUboot and is aware of the image format required by it, so that Device Firmware Upgrade is available when MCUboot is the boot loader used with Zephyr. The source code itself is hosted in the MCUboot GitHub Project page.

In order to use MCUboot with Zephyr you need to take the following into account:

You will need to define the flash partitions required by MCUboot; see Flash map for details.
You will have to specify your flash partition as the chosen code partition

/ {
   chosen {
      zephyr,code-partition = &slot0_partition;
   };
};

Your application’s .conf file needs to enable the CONFIG_BOOTLOADER_MCUBOOT Kconfig option in order for Zephyr to be built in an MCUboot-compatible manner
You need to build and flash MCUboot itself on your device
You might need to take precautions to avoid mass erasing the flash and also to flash the Zephyr application image at the correct offset (right after the bootloader)

More detailed information regarding the use of MCUboot with Zephyr can be found in the MCUboot with Zephyr documentation page on the MCUboot website.