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How to build the nRF52-U2F Firmware?¶

This section describes how to build a new nRF52-U2F firmware and bootloader for your security key.

Install Dependencies¶

To build the nRF52-U2F, you need to install some additional dependencies.

On Windows, the easiest way to install dependencies is to use the MSYS2. You can do so by performing the following steps:

Download and run the installer - "x86_64" for 64-bit, "i686" for 32-bit Windows.

Run MSYS2 from Start menu and install dependencies with:

# Update the package database and core system packages
$ pacman -Syu

# Install dependencies
$ pacman -S git make python2 openssl

Linux and macOS already have some necessary shell commands, run the following command to install the rest:

# On macOS
$ brew install openssl

# On Ubuntu
$ sudo apt-get install build-essential checkinstall openssl

Clone the nRF52-U2F Repository¶

To clone the nRF52-U2F source code repository from GitHub:

git clone --recursive https://github.com/makerdiary/nrf52-u2f

Download the nRF5 SDK¶

Download the SDK package from developer.nordicsemi.com.

The current version we are using is 15.2.0, it can be downloaded directly here: nRF5_SDK_v15.2.0_9412b96.zip

Extract the zip file into the nrf52-u2f/nrf_sdks/ directory. This should give you the following folder structure:

./nrf52-u2f/
├── LICENSE.md
├── README.md
├── boards
├── certs
├── docs
├── external
├── firmware
├── include
├── material
├── mkdocs.yml
├── nrf_sdks
│   ├── README.md
│   └── nRF5_SDK_15.2.0_9412b96
├── open_bootloader
├── source
└── tools

Install GNU Arm Embedded Toolchain¶

Download and install a GNU ARM Embedded build for your operating system and extract it on your file system.

Note

The current version we are using is 6-2017-q2-update.

Config the toolchain path in makefile.windows or makefile.posix depending on platform you are using. That is, the .posix should be edited if your are working on either Linux or macOS. These files are located in:

<nRF5 SDK>/components/toolchain/gcc

Open the file in a text editor and make sure that the GNU_INSTALL_ROOT variable is pointing to your GNU Arm Embedded Toolchain install directory. For example:

GNU_INSTALL_ROOT := $(HOME)/gcc-arm-none-eabi/gcc-arm-none-eabi-6-2017-q2-update/bin/
GNU_VERSION := 6.3.1
GNU_PREFIX := arm-none-eabi

Generate Attestation Key and Certificate¶

For more security, remember to generate a new attestation key and certificate.

Change to the tools directory, run the generate-certs.sh to generate a new attestation key and certificate:

$ cd ./nrf52-u2f/tools

$ ./generate-certs.sh

If successfully completed, the private key and certificate are stored in certs/keys.c file.

Build the U2F Firmware¶

Now you are ready to build nRF52-U2F source code.

Open terminal and change directory to:

# For nRF52840-MDK board
$ cd ./nrf52-u2f/boards/nrf52840-mdk/armgcc
$ make clean && make

# For nRF52840 Micro Dev Kit USB Dongle
$ cd ./nrf52-u2f/boards/nrf52840-mdk-usb-dongle/armgcc
$ make clean && make

The firmware is in the armgcc/_build/ directory with the name nrf52840_xxaa.hex.

Note

Please follow the Upgrading Firmware guide to flash the new firmware!

Build the Open Bootloader¶

The nRF52-U2F contains a reliable open bootloader, which means that you can update the nRF52-U2F firmware from USB directly without an external programmer needed.

You can build a new bootloader by performing the following steps:

Open terminal and change directory to:

# For nRF52840-MDK board
$ cd ./nrf52-u2f/open_bootloader/nrf52840-mdk/armgcc
$ make clean && make
$ make mergehex

# For nRF52840 Micro Dev Kit USB Dongle
$ cd ./nrf52-u2f/open_bootloader/nrf52840-mdk-usb-dongle/armgcc
$ make clean && make
$ make mergehex

The bootloader is in the armgcc/_build/ directory with the name nrf52840_xxaa_mbr.hex.

Note

Please follow the Upgrading Firmware guide to flash the new bootloader!

Create an Issue¶

Interested in contributing to this project? Want to report a bug? Feel free to click here: