Example project combining the Kendryte standalone SDK with an official FreeRTOS release.

An official FreeRTOS SDK for the K210 exists, but it is now deprecated. It's also rather weird in some aspects. This project allows you to use the Kendryte K210 RISC-V processor with the official FreeRTOS kernel and the still (somewhat) maintained standalone Kendryte SDK.

Most of the CMake configuration in the SDK is replaced with more canonical ways of doing things, e.g. the use of a toolchain file. This causes less issues e.g. with IDE integration. A miniumum CMake version of 3.12 is required now.

After cloning the repository, make sure you have initialized and updated the submodules, too, like so:

$ git submodule init
$ git submodule update

Create a build directory and run CMake and make:

$ mkdir build
$ cd build
$ cmake -DKENDRYTE_TOOLCHAIN=/absolute/path/to/kendryte/toolchain ..
$ make

Specifying KENDRYTE_TOOLCHAIN can be omitted if it is installed in the default location /opt/kendryte-toolchain. The path must point to the toolchain directory, not the bin directory inside it (as the Kendryte SDK requires).

At the time of this writing, after running make, a compiler error will occur in FreeRTOS-Kernel/portable/GCC/RISC-V/portmacro.h:85. Simply commenting out the #error line will solve this.

Copy the contents of or fork this repository. Place your source files into the src directory and add the file names to CMakeLists.txt (where src/main.c already is).

• The #error in portmacro.h described above.
• Saving and restoring floating point registers on context switches is untested.
• Current develop branch of the SDK does not work with this (it didn't even work on its own last time I tried).
• configTICK_RATE_HZ must be set higher by a factor 50 than you want it to be.
• printf and other APIs relying on syscall don't work after the scheduler has started. This is due to the FreeRTOS trap handler intercepting the interrupts.
• Inter-processor interrupts probably won't work for the same reason.