1## Overview
2
3This directory provides an SMP FreeRTOS-Kernel port that can be used with the Raspberry Pi Pico SDK. It supports:
4
5 * Simple CMake INTERFACE libraries, to provide the FreeRTOS-Kernel and also the individual allocator types, without copying code into the user's project.
6 * Running the FreeRTOS-Kernel and tasks on either core 0 or core 1, or both.
7 * 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.
8
9Note that whilst this SMP version can be run on just a single (either) core, it is probably
10more efficient to use the non SMP version in the main FreeRTOS-Kernel branch in that case.
11
12## Using this port
13
14You can copy [FreeRTOS_Kernel_import.cmake](FreeRTOS_Kernel_import.cmake) into your project, and
15add the following in your `CMakeLists.txt`:
16
17```cmake
18include(FreeRTOS_Kernel_import.cmake)
19```
20
21This will locate the FreeRTOS kernel if it is a direct sub-module of your project, or if you provide the
22`FREERTOS_KERNEL_PATH` variable in your environment or via `-DFREERTOS_KERNEL_PATH=/path/to/FreeRTOS-Kernel` on the CMake command line.
23
24**NOTE:** If you are using version 1.3.1 or older of the Raspberry Pi Pico SDK then this line must appear before the
25`pico_sdk_init()` and will cause FreeRTOS to be included/required in all RP2040 targets in your project. After this SDK
26version, you can include the FreeRTOS-Kernel support later in your CMake build (possibly in a subdirectory) and the
27FreeRTOS-Kernel support will only apply to those targets which explicitly include FreeRTOS support.
28
29As an alternative to the `import` statement above, you can just add this directory directly via thw following (with
30the same placement restrictions related to the Raspberry Pi Pico SDK version above):
31
32```cmake
33add_subdirectory(path/to/this/directory FreeRTOS-Kernel)
34```
35
36
37## Advanced Configuration
38
39Some additional `config` options are defined [here](include/rp2040_config.h) which control some low level implementation details.
40
41## Known Limitations
42
43- Tickless idle has not currently been tested, and is likely non-functional
44