Libuavcan platforms

In the context of Libuavcan, a platform is a particular hardware platform or an operating system that can execute libuavcan-based DroneCAN nodes. For example, the STM32 microcontroller family and the GNU/Linux OS are some of the officially supported libuavcan platforms.

A platform driver is a set of platform-specific C++ classes that implement the thin layer of glue logic needed to make libuavcan function with the particular platform at hand.

Adding support for a new platform

Implementing a platform driver for libuavcan is generally a quite straightforward task, especially if the driver is targeted for a certain application and need not to be generic.

Essentially, a libuavcan driver is a set of C++ classes implementing the following C++ interfaces:

• uavcan::ICanDriver
• uavcan::ICanIface
• uavcan::ISystemClock

The interfaces listed above are defined in libuavcan/include/uavcan/driver/.

Note that the library core already includes a non-blocking prioritized TX queue, so normally a driver should not implement a software TX queue itself.

If the driver does not need to support redundant CAN bus interfaces, then the first two C++ interfaces can be implemented in the same C++ class.

Some features can be left unimplemented:

• IO flags - needed for dynamic node ID allocation and time synchronization master.
• TX timestamping - needed for clock synchronization master.
• Hardware CAN filters configuration - not necessary if there is enough computational power to delegate filtering to the library software.

There are two extreme examples of the driver complexity level that can give a basic idea of the development effort required:

• LPC11C24 driver - only necessary functionality, no redundant interface support, no TX timestamping - 600 LoC.
• Linux driver - complete full-featured driver with hardware timestamping and redundant interfaces - 1200 LoC.

Contributions adding support for new platforms are always welcome.

Officially supported platforms

Official platform drivers are located in dedicated repositories here: github.com/DroneCAN. Contributions adding support for new platforms are always welcome.

Please refer to the platform driver source repositories for relevant documentation:

• STM32
• GNU/Linux
• NXP LPC11C24

POSIX helpers

This is not a complete driver, but rather a set of C++ classes that implement certain libuavcan interfaces in a cross-platform way, so that they can be used on any POSIX-compliant operating system, e.g. Linux or NuttX. The libuavcan tutorials available in an adjacent section cover how to use these classes among other things.

The driver is implemented as a header-only C++ library. The sources can be found in the main libuavcan source repository.

At least the following classes are implemented in the POSIX driver:

• Firmware version checker - implements a simple firmware version checking strategy for firmware update servers.
• File server backend - implements file system I/O for UAVCAN file management services.
• File system backends for dynamic node ID allocation servers.