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beechwoods-software / zephyr-cyw43-driver

Zephyr out of tree build for image with cyw43-driver
MIT License
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cyw43-driver module for the Zephyr OS

This is an integration of the georgerobotics cyw43-driver code for use with the Zephyr OS and its native IP stack. It currently only contains board support for Raspberry Pi Pico hardware, but can easily be extended to others.

Building a sample Zephyr image

Set up Zephyr development environment

In order to build a Zephyr image that contains cyw43-driver WiFi support, it is necessary to have a Zephyr development environment. If you have not done this, follow the Zephyr project's Getting Started Guide: https://docs.zephyrproject.org/latest/develop/getting_started/index.html

Build the example application

Once you've set up the Zephyr development environment, you can use the west tool and code in this repository to build a Raspberry Pi Pico image with cyw43-driver WiFi support by following the step below. These instructions will do an out-of-tree build of Zephyr 3.6. For info on building for Zephyr 3.7, see the note at the bottom of this README.

  cd <directory where you want your zephyr build workspace>
  west init -m https://github.com/beechwoods-software/zephyr-cyw43-driver --mr main my-workspace
  cd my-workspace
  (cd zephyr-cyw43-driver; git submodule init; git submodule update)
  west update
  cd zephyr-cyw43-driver
  west build -b rpi_pico_w app

Once the build is finished, you should find a uf2 image cyw43-driver/zephyr_buildbuild/zephyr/zephyr.uf2 that can be flashed onto the device using the instructions here: https://projects.raspberrypi.org/en/projects/getting-started-with-the-pico/3 The build process will also produce images in other formats (the elf format image is useful if you want to run your code in a debugger).

The image will run the Zephyr network shell on the serial console, which can be used to set up a wifi connection with the command:

  uart:~$ wifi connect <your ssid> <your passphrase>

You can see the full set of wifi subcommands, which can be used to set up an access point or perform other wifi management and control functions, by issuing the wifi command with no arguments.

Autoconnecting to your wifi network

If you wish for your image to automatically connect to your own wifi network, uncomment the two lines in app/local.conf and fill them in with your wifi credentials.

Providing support for other boards

In order to provide support for other boards, a device tree source overlay file will need to be provided to tell the build how the cyw43 module is connected to the system (SDIO or SPI, and which particular pins to be used for that connection).

The overlay file for the Pico W can be used as an example:

cyw43-driver/zephyr_build/app/boards/rpi_pico_w.overlay

Zephyr 3.7 support

Note that the instructions above will still build a Zephyr 3.6 image. This is because there is a serious bug in v3.7.0, which causes fatal exceptions on the ARM Cortex M0 architecture that the RP2040 uses. For info about this issue and the patch required to fix it, see: https://github.com/zephyrproject-rtos/zephyr/commit/b24c5201a0ab9de8395e73a4c52d49bf084143f0

You can build a 3.7 image based on a changeset that isn't in an official release yet by replacing "--mr main" with "--mr 3.7_dev" in the build instructions above. Presumablly this bug-fix will be included in Zephyr release v3.7.1, so when that becomes available, I'll make 3.7.1 based builds the default on the main branch of the zephyr-cyw43-driver repository.