USB DFU (Device Firmware Upgrade)
Overview
This sample app demonstrates use of a USB DFU Class driver provided by the Zephyr project.
Requirements
This project requires an USB device driver. Currently, the USB DFU class provided by the Zephyr project depends on DFU image manager and partition layout. Refer to Flash map for details about partition layout. You SoC must run MCUboot as the stage 1 bootloader. This sample is built as an application for the MCUboot bootloader.
Note
This example explicitly turns CONFIG_USB_DFU_ENABLE_UPLOAD on.
Building and Testing
Building and signing the application
This sample can be built in the usual way (see Building an Application for more details) and flashed with regular flash tools, but will need to be loaded at the offset of SLOT-0.
Application images (such as this sample) must be signed.
The build system can do this for you by setting the CONFIG_MCUBOOT_SIGNATURE_KEY_FILE symbol.
For example:
west build -b nrf52840dk/nrf52840 zephyr/samples/subsys/usb/dfu -d build-dfu -- \
-DCONFIG_MCUBOOT_SIGNATURE_KEY_FILE=\"bootloader/mcuboot/root-rsa-2048.pem\"
Build and flash MCUboot bootloader for Zephyr project as it is described in the Using MCUboot with Zephyr documentation. Then build, sign and flash the USB DFU sample at the offset of SLOT-0.
Build and sign a second application image e.g. Hello World,
which will be used as an image for the update.
Do not forget to enable the required CONFIG_BOOTLOADER_MCUBOOT option (as described
in MCUboot). For example:
west build -b nrf52840dk/nrf52840 zephyr/samples/hello_world -d build-hello_world -- \
-DCONFIG_BOOTLOADER_MCUBOOT=y '-DCONFIG_MCUBOOT_SIGNATURE_KEY_FILE="bootloader/mcuboot/root-rsa-2048.pem"'
Testing
The Linux dfu-util tool can be used to backup or update the application
image.
Use the following command to backup the SLOT-0 image:
dfu-util --alt 0 --upload slot0_backup.bin
Use the following command to update the application:
dfu-util --alt 1 --download build-hello_world/zephyr/zephyr.signed.bin
Reset the SoC. MCUboot boot will swap the images and boot the new application, showing this output to the console:
*** Booting Zephyr OS build zephyr-v3.0.0-360-gc0dd594d4d3d ***
I: Starting bootloader
I: Primary image: magic=good, swap_type=0x3, copy_done=0x1, image_ok=0x1
I: Secondary image: magic=good, swap_type=0x2, copy_done=0x3, image_ok=0x3
I: Boot source: none
I: Swap type: test
I: Bootloader chainload address offset: 0xc000
I: Jumping to the first image slot
*** Booting Zephyr OS build zephyr-v3.0.0-361-gb987e6daa2f9 ***
Hello World! nrf52840dk
Reset the SoC again and MCUboot should revert the images and boot USB DFU sample, showing this output to the console:
*** Booting Zephyr OS build zephyr-v3.0.0-360-gc0dd594d4d3d ***
I: Starting bootloader
I: Primary image: magic=good, swap_type=0x2, copy_done=0x1, image_ok=0x3
I: Secondary image: magic=unset, swap_type=0x1, copy_done=0x3, image_ok=0x3
I: Boot source: none
I: Swap type: revert
I: Secondary image: magic=unset, swap_type=0x1, copy_done=0x3, image_ok=0x3
I: Bootloader chainload address offset: 0xc000
I: Jumping to the first image slot
*** Booting Zephyr OS build zephyr-v3.0.0-361-gb987e6daa2f9 ***
[00:00:00.005,920] <inf> main: This device supports USB DFU class.
Permanent download and automatic reboot
There are some symbols that can be used to enable a hands free download:
To mark SLOT-1 as permanent after the download completes,
enable the CONFIG_USB_DFU_PERMANENT_DOWNLOAD symbol.
To automatically reboot after the download completes,
enable the CONFIG_USB_DFU_REBOOT symbol.
Warning
Enabling CONFIG_USB_DFU_PERMANENT_DOWNLOAD can lead to a bricked device!
Make sure there is another way to download firmware.
For example via a debugger or Mcuboot’s recovery mode.
Both symbols can be enabled with the overlay-permanent-download.conf overlay. For example:
west build -b nrf52840dk/nrf52840 zephyr/samples/subsys/usb/dfu -d build-dfu -- \
-DCONFIG_BOOTLOADER_MCUBOOT=y '-DCONFIG_MCUBOOT_SIGNATURE_KEY_FILE="bootloader/mcuboot/root-rsa-2048.pem"' \
-DEXTRA_CONF_FILE=overlay-permanent-download.conf
The listing below shows the output to the console when downloading via dfu-util.
Note the Swap type: perm.
*** Booting Zephyr OS build zephyr-v3.0.0-361-ge6900e2451d5 ***
[00:00:00.005,920] <inf> main: This device supports USB DFU class.
*** Booting Zephyr OS build zephyr-v3.0.0-360-gc0dd594d4d3d ***
I: Starting bootloader
I: Primary image: magic=good, swap_type=0x4, copy_done=0x1, image_ok=0x1
I: Secondary image: magic=good, swap_type=0x3, copy_done=0x3, image_ok=0x1
I: Boot source: none
I: Swap type: perm
I: Bootloader chainload address offset: 0xc000
I: Jumping to the first image slot
*** Booting Zephyr OS build zephyr-v3.0.0-361-gb987e6daa2f9 ***
Hello World! nrf52840dk