LoRa Basics Modem on Zephyr

This repository aims to make LoRa Basics Modem available in Zephyr. It wraps the existing SWL2001 repository from Semtech.

At term, this repository might be merged into the upstream Zephyr project.

This is an experimental release of demo projects of LBM on Zephyr, tested on LR11xxMB1LxKS shields

Zephyr module

You can use this module either as your "west manifest project", or include it in another project. In that case you need to add import: true to the caller configuration, as this:

  projects:
    - name: lbm_zephyr
      path: modules/lbm_zephyr
      remote: lora-net
      repo-path: lbm_zephyr
      revision: main
      import: true

Requirements

You need a recent Linux distribution (Python >= 3.10, CMake >= 3.20.5).

Install west and Zephyr SDK

You need to install the Zephyr SDK (compiler and flashing tools) and west (the build system tool).

Please follow instructions at https://docs.zephyrproject.org/latest/develop/getting_started/index.html. You will only need to follow this step only once for all your Zephyr projects.

Activate the Zephyr virtual environment (if not already activated)

If it's not installed in your system, you need to load the Zephyr SDK environment each time you open a new terminal:

source ~/zephyrproject/.venv/bin/activate

Download code

This repository only contains specific LBM port code and the samples. We also need to download Zephyr itself, LBM, and associated HAL modules.

You need to create an empty directory, let's name it lbm_zephyr_workspace, and clone the current repository inside it.

mkdir lbm_zephyr_workspace
cd lbm_zephyr_workspace
git clone [email protected]:lora-net/LBM_Zephyr.git lbm_zephyr

The SWL2001 repository will be automatically downloaded, you don't need to clone it yourself.

Download Zephyr and its modules

Then, initialize West (the build tool): Multiple repositories will be automatically downloaded inside the workspace directory.

west init -l lbm_zephyr
west update

It will take 3-10 minutes to run depending on your network connection.

You will need to run this step for every project you download.

If major updates to lbm_zephyr are provided, you might need to run west update again.

The samples

Samples are in the lbm_zephyr/samples directory, split in two classes:

• lora_drivers: Samples only using the low level LoRa drivers
  • ping_pong : Flash this sample to two boards to see them talk.
  • ping_shell : Same as ping_pong, but manually, using the Zephyr shell ! run lorademo ping in one board to ping the other flashed board.
• lora_basics_modem: Samples leveraging the LBM stack to communicate with LoRaWAN networks.
  • app_demo_periodical_uplink: This sample joins a network and periodically sends packets. You can also send a packet manually by pressing the button (on nRF52840dk it's BUTTON 1). Please configure your device EUIs/App keys in src/example_options.h
  • app_lbm_hw_modem: used for continuous integration tests. It expects serial communication on an UART port. Read src/hw_modem/cmd_parser.c for explanations.

Build the code

You need to inform Zephyr which board and shield you want to use. Shields are in the lbm_zephyr/boards/shields/* directories as .overlay files. They describe which transceiver model you are using. For example, semtech_lr1110mb1xxs.

Go into a sample's directory, then run:

west build --board nrf52840dk/nrf52840 -- -DSHIELD=semtech_lr1110mb1xxs
# or
west build --board nucleo_l476rg --build-dir build_nucleo -- -DSHIELD=semtech_lr1110mb1xxs

It will build your project in the build subdirectory (can be configured by --build-dir). You can pass --pristine to ensure the build directory is clean.

The boards are expected to have a lora0 node label. The shield semtech_lr1110mb1xxs provides it.

You might want to customize the LoRa transceiver configuration by adding a file in the boards subdirectory or via app.overlay. For example, to set a TCXO instead of the default XTAL:

&lora_semtech_lr11xxmb1xis {
    tcxo-wakeup-time = <7>;
};

Flash the board

west flash
# or
west flash --build-dir build_nucleo

For the nRF52840-DK board, you don't need to close open serial ports during flash.

Open the serial port

You can use minicom, picocom, tio,…

tio /dev/serial/by-id/usb-SEGGER_J-Link_*-if00