Overview

This directory provides a 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
• Use of SDK synchronization primitives (such as mutexes, semaphores, queues from pico_sync) between FreeRTOS tasks and code executing on the other core, or in IRQ handlers.

Note that a FreeRTOS SMP version of this port is also available in the FreeRTOS-Kernel smp branch, which additionally supports utilizing both RP2040 CPU cores for FreeRTOS tasks simultaneously.

Using this port

You can copy FreeRTOS-Kernel-import.cmake into your project, and add the following in your CMakeLists.txt:

import(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