Dragonet

Multi-core pub/sub IPC framework for embedded systems

Publish-subscribe IPC framework for heterogenous multi-core embedded systems running Linux and FreeRTOS, using LCM, RPMsg, and FreeRTOS queues. Currently supports the i.MX 6SoloX (tested on Dragonflyte flight computer).

Setup

Installing on Linux

For the MPU side running Linux, the package is built as a shared library. You will also need to modify the RPMsg-char driver (available in Linux >= 4.11) with this patch.

Install LCM by following the instructions here. Then, run the following commands in the repository directory to install the Dragonet library.

cmake .
make
make install

To use the library in your own project, link the library and include dragonet.h.

Running in Linux

Run the following commands before running the library. This assumes that the RPMsg-char driver is built as a kernel module, and that the MCU side is already running a Dragonet instance.

insmod /lib/modules/[kernel_version]/kernel/drivers/rpmsg/rpmsg_char.ko
ifconfig lo multicast
route add -net 224.0.0.0 netmask 240.0.0.0 dev lo

Building with FreeRTOS

For the MCU side, the library is built as a static library that is linked into a C++ project that has FreeRTOS and RPMsg-Lite (v2.0.0) included already. If you are using CMake, you can include cmake/DragonetStatic.cmake as well as inc/platform/[platform]/dragonet_platform.h from your CMakeLists.txt, and then link the library into your project. Include dragonet.h in the rest of the project to use the library.

Usage

The usage of the library is the same regardless of the platform. On Linux, only one instance of the Dragonet object should be created per process. On an MCU running FreeRTOS, there can only be one Dragonet instance in the entire program. This usually means the instance is created on startup and passed to several FreeRTOS tasks. Init() must be called before the other functions can be used. On FreeRTOS, Init() must be called after the scheduler starts, usually by calling vTaskStartScheduler(). This means Init() will have to be called inside a task. Because multiple tasks will attempt to call Init(), it is designed to allow this.

Subscriber example

dragonet::Dragonet dragonet_;
int callback(const int *data)
{
  // Do something
}
int main()
{
  dragonet_.Init();
  dragonet_.Subscribe("channel-name", callback);
  dragonet_.Spin();
}

Publisher example

dragonet::Dragonet dragonet_;
int main()
{
  dragonet_.Init();
  for (int data = 0; data < 10; data++)
  {
    dragonet_.Publish("channel-name", &data);
  }
}