The following guide offers step-by-step instructions on how to prepare and program the DFU example application, create a DFU file that contains example firmware, and transfer it. This guide should make it easy to use the mesh DFU to transfer any firmware to any device on the mesh network.
The DFU example included in the nRF5 SDK for Mesh demonstrates the background mode DFU. Make sure you are familiar with the whole Mesh DFU protocol documentation configuring DFU over Mesh.
Table of contents
To perform DFU transfers over mesh:
nrfutil
tool. This tool sends the DFU packets to one device over serial interface. This device then stores these packets, and also forwards them to the other devices withing the radio range. The nrfutil is available at https://github.com/NordicSemiconductor/pc-nrfutil/tree/mesh_dfu. The tool is open source. mesh_dfu
branch mentioned above. See the tool's documentation for more information about installation and prerequisites.-s <serial-number>
option for each call to the nrfjprog
command, where <serial-number>
is the SEGGER ID of your device. This will make nrfjprog
execute its operations on the specified device only.intelhex
package is installed for your Python installation.Before you start the proper Mesh DFU configuration process, you can decide whether you want to generate a signing file with nrfutil and add the public key from nrfutil to your device page.
DFU images can be signed to ensure they stem from a trusted source. If you want to use this signature verification functionality, you need a signing key.
Use the nrfutil tool to generate a signing key. Run the following command:
This command creates a private_key.txt
file in your current directory.
This key must only be shared with trusted sources. If you lose it, you also lose the authorization to do DFU updates to your devices in the future. The only way to recover from the loss of the private key is to reflash the device manually.
Now that you have a private key, you can generate the public key for it, which you can safely share with everyone. You must then add this public key to the bootloader configurator file, which is used to create the device page. For details about the device page generator script, see DFU Utilities and Tools.
Complete the following steps:
tools/dfu
folder, edit the bootloader_config_default.json
file to prepare the device page:"public_key"
.Qx
and Qy
strings to this key. For example: Optionally, you can also change the company ID entry in the device page. The company ID works as a namespace for application IDs in the mesh DFU. In this way, any company with an assigned company ID can use any application ID for its products, without risking an application ID conflict.
In the example, the company ID is set to 89
, which is the decimal version of Nordic Semiconductor's Bluetooth SIG assigned Company ID. If your company has an assigned ID, you can use that ID number. If you do not represent a company with an assigned ID, use a random 32-bit number higher than 65535.
Complete the following steps to configure the background mode mesh DFU:
To do a DFU transfer, you must create a DFU archive with nrfutil, giving arguments that match the device page. The DFU archive is a zip file that contains the application binary along with some metadata.
You need the HEX file of an example application that causes a LED to blink on the boards. The file is generated when you build the mesh stack and is located in the bin/blinky
folder. Use the HEX file that corresponds to the chip and the SoftDevice you are using.
To generate the DFU archive, run the nrfutil
command that corresponds to your SoftDevice. For example:
This command generates a DFU archive called dfu_test.zip
in the current directory. You can call nrfutil dfu genpkg --help
to get a list of possible command line arguments and their meaning.
--company-id
and the --application-id
values must match the values used for generating the device page. The --application-version
must be higher than the version number that you used for the previous firmware image.To generate a HEX version of your device page, use the device_page_generator.py
script located in the device page file folder: tools/dfu
. For details about the device page generator script, see DFU Utilities and Tools.
You have to specify the device series (-d
option), and the SoftDevice version (-sd
option). All device pages contain a SD_VERSION
entry, which must match the --sd-req
value passed to nrfutil
when generating the DFU archive in the previous step. Failing to match the SoftDevice version requirement parameters will make the device reject the transfer, as its own firmware ID will not match the one in the transfer.
To generate a device page hex file for an nRF52 Series device using s132 SoftDevice version 6.1.0, run the following command from inside the tools/dfu
folder:
This creates a device page HEX file in the tools\dfu\bin
folder. This file will be used for flashing the first application on all devices.
Use nrfjprog (available on nordicsemi.com) to erase all data on your device (including UICR) and flash the SoftDevice.
SoftDevices for the nRF51 and nRF52 chips are located in the bin/softdevice
folder.
Run the following nrfjprog command with the correct name of the HEX file:
For example, to erase data and flash the S132 SoftDevice v6.1.0, run the following command:
For this step, use the precompiled bootloader with the serial support. You can find the precompiled versions of the bootloader under bin/
. The bootloader version must match your chip version, as per table.
Chip version | Bootloader |
---|---|
nRF51422_xxAC | mesh_bootloader_serial_<compiler>_nrf51422_xxAC.hex |
nRF52832_xxAA | mesh_bootloader_serial_<compiler>_nrf52832_xxAA.hex |
nRF52840_xxAA | mesh_bootloader_serial_<compiler>_nrf52840_xxAA.hex |
Flash the precompiled bootloader with the following nrfjprog command:
For example, you can run the following command to flash a bootloader compiled with GCC ARM compiler on an nRF52832_xxAA device:
To be able to do Device Firmware Updates, you must flash an application that supports DFU. You can use the DFU example application in examples/dfu/
.
You must flash the DFU example application from your build folder, using the HEX file that matches your chip version and SoftDevice. For example, build/examples/dfu/dfu_nrf52832_xxAA_s132_6.1.0.hex
if your device is an nRF52832_xxAA
with the s132 SoftDevice v6.1.0.
Run the following nrfjprog command:
To flash the device page HEX file to the devices, run the following nrfjprog command:
Then, reset the device to start the application:
After the reset, observe that for every development kit that you programmed, all LEDs are OFF. At this point, you have everything ready for performing the DFU over the mesh.
Before you start transfering data:
dmesg
command after you have plugged in a device to see which serial port file has been assigned to the device. The serial ports for J-Link devices are called ttyACMx, where x is an integer, and are located in the /dev
directory.To start the DFU transfer, run the following command:
A progress bar appears. The transfer takes a couple of minutes.
--verbose
before the arguments, as follows: nrfutil --verbose dfu serial -pkg dfu_test.zip -p <COM port> -b 115200 -fc --mesh
.When finished, the bootloader switches to the application and one of the LEDs starts blinking on each kit. Note that you cannot do the DFU twice with the same DFU archive, because the application version in the device page on your device is incremented to the latest version. Therefore, the bootloader will reject any attempt to transfer the same firmware again.
To try another DFU transfer, run the configuration steps and the transfer command again, but with an increased version number. For example, --application-version 3
. Also, use the new zip file.
To verify that the bootloader is working correctly, run the bootloader verification script.