Important
This core is in BETA. 🧪
Features may change, and bugs may be present. Use for testing only and provide feedback to help us improve.
This repository contains the official implementation of Arduino Core for Zephyr RTOS based board.
Zephyr RTOS is an open-source, real-time operating system designed for low-power, resource-constrained devices. It's modular, scalable, and supports multiple architectures.
Install the core and its toolchains via Board Manager:
- Download and install the latest Arduino IDE (only versions
2.x.xare supported). - Open the 'Settings / Preferences' window.
- Open the 'Boards Manager' from the side menu and search for 'Zephyr'.
- If it doesn’t appear, add the following URL to the 'Additional Boards Manager URLs' field:
https://downloads.arduino.cc/packages/package_zephyr_index.json(if you have multiple URLs, separate them with a comma).
- If it doesn’t appear, add the following URL to the 'Additional Boards Manager URLs' field:
- Install the
Arduino Zephyr Boardsplatform.
Alternatively, to install the core using the command line, run the following command with the Arduino CLI:
arduino-cli core install arduino:zephyr --additional-urls https://downloads.arduino.cc/packages/package_zephyr_index.jsonTo get started with your board:
- Put the board in bootloader mode by double-clicking the RESET button.
- Run the
Burn Bootloaderoption from the IDE/CLI.- Note that due to limitations in the Arduino IDE, you may need to select any programmer from the
Programmersmenu.
- Note that due to limitations in the Arduino IDE, you may need to select any programmer from the
- Once the bootloader is installed, you can load your first sketch by placing the board into bootloader mode again.
Note
After the initial setup, future sketches will be loaded automatically without needing to reset the board.
A: Connect a USB-to-UART adapter to the default UART (eg. TX0/RX0 on Giga, TX/RX on Nano) and read the error message (with the sketch compiled in Default mode). If you don't own a USB-to-UART adapter, compile the sketch in Debug mode; this will force the shell to wait until you open the Serial Monitor. Then, run sketch command and probably you'll be able to read the error (if generated by llext). For OS crashes, the USB-to-UART adapter is the only way to collect the crash.
A: This means you are trying to use a Zephyr function which has not yet been exported. Open llext_exports.c, add the function you need and recompile/upload the loader.
A: Open the .conf file for your board, add the required CONFIG_, recompile/upload the loader.
A: This is usually due to a buffer overflow or coding error in the user's own code. However, since the project is still in beta 🧪, a good bug report could help identify any issues in our code.
A: Since collecting bug reports is very important at this time, we are keeping Zephyr's shell enabled to allow loading a full sketch (which requires a large stack). Adjust your board's .conf file to reduce the stack size if your platform doesn't have enough RAM.
- ArduinoBLE: This library is enabled only for the Arduino Nano 33 BLE. Please use this branch to test it.
Unlike traditional Arduino implementations, where the final output is a standalone binary loaded by a bootloader, this core generates a freestanding elf file. This file is dynamically loaded by a precompiled Zephyr firmware, referred to as the loader.
The loader is responsible for managing the interaction between your sketches and the underlying Zephyr system. After the initial bootloader installation, the loader takes over the sketch loading process automatically.
To ensure flexibility, the loader project is designed to be generic. Any necessary modifications for specific boards should be made in the corresponding "DTS overlay" or a special "fixup" file, using appropriate guards to maintain compatibility.
The behavior of the loader can be adjusted through the Mode menu of the IDE:
Standard: The sketch is loaded automatically.Debug: The user must typesketchin Zephyr's shell, which is accessible via the default Serial.
The most important components of this project are:
- Zephyr based loader
- LLEXT
- Actual core with variants and the usual platform and boards files
- ArduinoCore-API
- zephyr-sketch-tool
Tip
If you are only interested in developing features in the core
or libraries, and do not want to set up a full Zephyr build
environment, you can use the sync-zephyr-artifacts
utility to download a pre-built version of the files needed to compile
sketches and flash the loader.
To do so, after cloning this repo, compile the sync-zephyr-artifacts
utility via go build and run it as sync-zephyr-artifacts . to retrieve
the precompiled files for the current revision of the core.
Next, follow the instructions in Using the Core in Arduino IDE/CLI. Remember to update the loader on your board as well.
In this section, we’ll guide you through setting up your environment to work on and update the Zephyr core.
Shell scripts are available to simplify the installation process (Windows is not supported at the moment 😔).
mkdir my_new_zephyr_folder && cd my_new_zephyr_folder
git clone https://github.com/arduino/ArduinoCore-zephyrBefore running the installation script, ensure that Python, pip and venv are installed on your system. The script will automatically install west and manage the necessary dependencies.
On Ubuntu or similar apt-based distros, make sure to run the following command:
sudo apt install python3-pip python3-setuptools python3-venv build-essential git cmake ninja-build zstd jqcd ArduinoCore-zephyr
./extra/bootstrap.shThis will take care of installing west, the Zephyr build tool. It will then
download all packages required for a Zephyr build in addition to the toolchains
in the Zephyr SDK.
Note
This core is validated with version v0.17.0 of the SDK. Compatibility with later versions has not been tested yet.
The loader is compiled for each board by running the ./extra/build.sh script.
The target can be specified either with the Arduino board name (as defined in
boards.txt), or with the Zephyr board name and any additional arguments that
may be required by the Zephyr build system.
For example, to build for the Arduino Portenta H7, you can use either the Arduino name:
./extra/build.sh portentah7or the Zephyr board target:
./extra/build.sh arduino_portenta_h7//m7The firmwares will be copied to the firmware folder, and the associated variant will be updated.
If the board is fully supported by Zephyr, you can flash the firmware directly onto the board using the following command:
west flashThis can also be performed via the "Burn bootloader" action in the IDE if the core is properly installed, as detailed below.
After running the bootstrap.sh script, you can symlink the core to $sketchbook/hardware/arduino-git/zephyr. Once linked, it will appear in the IDE/CLI, and the board's Fully Qualified Board Name (FQBN) will be formatted as arduino-git:zephyr:name_from_boards_txt.
Tip
While Zephyr supports a lot of different hardware targets, only the few currently used by the Arduino core are installed by default. To add the support for every Zephyr target to your workspace, run the following commands:
. venv/bin/activate
west config -d manifest.project-filter
west sdk install --version 0.17.0
west updateTo add a new board that is already supported by mainline Zephyr with the target $your_board, follow these steps:
-
Get the variant name from your board by running
extra/get_variant_name.sh $your_board. -
Create a folder in the
variants/directory with the same name as the variant for your new board. -
Create the DTS
<variant>.overlayand Kconfig<variant>.conffiles in that directory.The overlay must include:
- A flash partition called
user_sketch, typically located near the end of the flash. - A
zephyr,usersection containing the description for GPIOs, Analog, UART, SPI and I2C devices. Feel free to leave some fields empty in case Zephyr support is missing. This will result in some APIs not being available at runtime (eg.analogWriteif PWM section is empty).
The Kconfig file must include any board-specific options required by this target.
- A flash partition called
-
Build the Loader: run
./extra/build.sh $your_board(with any additional arguments as required) and start debugging the errors. 😁 -
Update the
boards.txt: add an entry for your board, manually filling the required fields.Make sure to set:
build.zephyr_targetandbuild.zephyr_argsto the arguments used in thebuild.shcall;build.zephyr_halsto the (space-separated list of) HAL modules required by the board;build.variantto the variant name identified above.
-
Implement touch support: if your board supports the "1200bps touch" method, implement
_on_1200_bpsin a file located inside the variant folder of your board.
To report a bug, open the issues and follow the instructions. Any issue opened without the needed information will be discarded.
Contributions are always welcome. The preferred way to receive code contribution is by submitting a Pull request.
Warning
At this stage of development, we only accept Pull requests for bug fixes and features. We do not accept support for new targets.
- Remove binaries from this repo history (#102,
⚠️ will require a clean clone) - Network: support UDP and TLS
- USB: switch to
USB_DEVICE_STACK_NEXTto support PluggableUSB - Relocate RODATA in flash to accommodate sketches with large assets
- Provide better error reporting for failed llext operations
- Replace
llext_exports.cwith proper symbols generation (via includes) - Fix corner cases with
std::includes (like<iterator>) - Get rid of all warnings
This effort would have been very hard without the GSoC project and the Zephyr community.