CANnectivity is an open source firmware for Universal Serial Bus (USB) to Controller Area Network (CAN) adapters.
The firmware implements the Geschwister Schneider USB/CAN device protocol (often referred to as "gs_usb"). This protocol is supported by the Linux kernel SocketCAN gs_usb driver, by python-can, and by many other software packages.
The firmware, which is based on the Zephyr RTOS, allows turning your favorite microcontroller development board into a full-fledged USB to CAN adapter.
CANnectivity is licensed under the Apache-2.0 license.
The CANnectivity firmware supports the following features, some of which depend on hardware support:
- CAN classic support
- CAN FD (flexible data rate) support
- Fast-speed and Hi-speed USB support
- Support for multiple, independent CAN channels
- GPIO-controlled LED support
- CAN channel state LEDs
- CAN channel activity LEDs
- Visual CAN channel identification
- Support for GPIO-controlled CAN bus termination resistors
- Support for hardware timestamping of received and transmitted CAN frames
- CAN bus state reporting
- CAN bus error reporting
- Automatic gs_usb driver loading under Linux using custom udev rules
- Automatic WinUSB driver installation under Microsoft Windows 8.1 and newer
Since the CANnectivity firmware is based on the Zephyr RTOS, it requires Zephyr support for the board it is to run on. The board configuration must support both an USB device driver and at least one CAN controller.
Check the list of supported boards in the Zephyr documentation to see if your board is already supported. If not, have a look at the instructions in the board porting guide.
By default, CANnectivity relies on the
devicetree zephyr,canbus chosen node
property for specifying the CAN controller to use. If a devicetree alias for led0 is present, it
is used as status LED. This means that virtually any Zephyr board configuration supporting USB
device, a CAN controller, and an optional user LED will work without any further configuration.
Advanced board configuration (e.g. multiple CAN controllers, multiple LEDs, hardware timestamp counter) is also supported via devicetree overlays. Check the description for the cannectivity devicetree binding and example devicetree overlays.
Building the CANnectivity firmware requires a proper Zephyr development environment. Follow the official Zephyr Getting Started Guide to establish one.
Once a proper Zephyr development environment is established, inialize the workspace folder (here
my-workspace). This will clone the CANnectivity firmware repository and download the necessary
Zephyr modules:
west init -m https://github.com/CANnectivity/cannectivity --mr main my-workspace
cd my-workspace
west updateNext, build the CANnectivity firmware in its default configuration for your board (here
lpcxpresso55s16) using west:
west build -b lpcxpresso55s16/lpc55s16 cannectivity/app/To use the release configuration, which has reduced log levels, set FILE_SUFFIX=release:
west build -b lpcxpresso55s16/lpc55s16 cannectivity/app/ -- -DFILE_SUFFIX=releaseBuild configurations for using the experimental device_next USB device stack in Zephyr are also
provided. These can be selected by setting either FILE_SUFFIX=usbd_next or
FILE_SUFFIX=usbd_next_release.
After building, the firmware can be flashed to the board by running the west flash command.
The CANnectivity firmware repository is a Zephyr module which allows for reuse of its components (i.e. the "gs_usb" protocol implementation) outside of the CANnectivity firmware application.
To pull in CANnectivity as a Zephyr module, either add it as a West project in the west.yaml file
or pull it in by adding a submanifest (e.g. zephyr/submanifests/cannectivity.yaml) file with the
following content and run west update:
manifest:
projects:
- name: cannectivity
url: https://github.com/CANnectivity/cannectivity.git
revision: main
path: custom/cannectivity # adjust the path as needed
