Overview

This directory provides an SMP FreeRTOS-Kernel port that can be used with the Raspberry Pi Pico SDK. It supports:

• Simple CMake INTERFACE libraries, to provide the FreeRTOS-Kernel and also the individual allocator types, without copying code into the user's project.
• Running the FreeRTOS-Kernel and tasks on either core 0 or core 1, or both.
• Use of SDK synchronization primitives (such as mutexes, semaphores, queues from pico_sync) between FreeRTOS tasks and code executing on a non FreeRTOS core, or in IRQ handlers.

Note that whilst this SMP version can be run on just a single (either) core, it is probably more efficient to use the non SMP version in the main FreeRTOS-Kernel branch in that case.

Using this port

You can copy FreeRTOS_Kernel_import.cmake into your project, and add the following in your CMakeLists.txt:

include(FreeRTOS_Kernel_import.cmake)

This will locate the FreeRTOS kernel if it is a direct sub-module of your project, or if you provide the FREERTOS_KERNEL_PATH variable in your environment or via -DFREERTOS_KERNEL_PATH=/path/to/FreeRTOS-Kernel on the CMake command line.

NOTE: If you are using version 1.3.1 or older of the Raspberry Pi Pico SDK then this line must appear before the pico_sdk_init() and will cause FreeRTOS to be included/required in all RP2040 targets in your project. After this SDK version, you can include the FreeRTOS-Kernel support later in your CMake build (possibly in a subdirectory) and the FreeRTOS-Kernel support will only apply to those targets which explicitly include FreeRTOS support.

As an alternative to the import statement above, you can just add this directory directly via thw following (with the same placement restrictions related to the Raspberry Pi Pico SDK version above):

add_subdirectory(path/to/this/directory FreeRTOS-Kernel)

Advanced Configuration

Some additional config options are defined here which control some low level implementation details.

Known Limitations

• Tickless idle has not currently been tested, and is likely non-functional