FreeRTOS ======== Overview -------- This section contains documentation of FreeRTOS types, functions, and macros. It is automatically generated from FreeRTOS header files. .. note:: ESP-IDF FreeRTOS is based on Vanilla FreeRTOS v10.4.3 - For more information about the SMP changes of ESP-IDF FreeRTOS, see :doc:`/api-guides/freertos-smp` - For more information about the features added to ESP-IDF FreeRTOS, see :doc:`/api-reference/system/freertos_additions`. Configuration ------------- Vanilla FreeRTOS allows ports and applications to configure the kernel by adding various ``#define config...`` macros to ``FreeRTOSConfig.h``. Through these macros, the kernel's scheduling behavior and various kernel features can be enabled or disabled. **However, in ESP-IDF FreeRTOS, the ``FreeRTOSConfig.h`` file is considered a private and must not be modified by users**. Any FreeRTOS configuration that is exposed to the user will be done so via menuconfig. ESP-IDF FreeRTOS can be configured in the project configuration menu (``idf.py menuconfig``) under ``Component Config/FreeRTOS``. The following section highlights some of the ESP-IDF FreeRTOS configuration options. For a full list of ESP-IDF FreeRTOS configurations, see :doc:`/api-reference/kconfig` - :ref:`CONFIG_FREERTOS_UNICORE` will run ESP-IDF FreeRTOS only on CPU0. Note that this is **not equivalent to running Vanilla FreeRTOS**. Futhermore, this option may affect behavior of components other than :component:`freertos`. For more details regarding the effects of running ESP-IDF FreeRTOS on a single core, refer to :ref:`freertos-smp-single-core`. Alternatively, users can also search for occurrences of ``CONFIG_FREERTOS_UNICORE`` in the ESP-IDF components. - :ref:`CONFIG_FREERTOS_TASK_FUNCTION_WRAPPER` will enclose all task functions within a wrapper function. In the case that a task function mistakenly returns (i.e. does not call :cpp:func:`vTaskDelete`), the call flow will return to the wrapper function. The wrapper function will then log an error and abort the application, as illustrated below:: E (25) FreeRTOS: FreeRTOS task should not return. Aborting now! abort() was called at PC 0x40085c53 on core 0 .. only:: CONFIG_FREERTOS_UNICORE .. note:: As {IDF_TARGET_NAME} is a single core SoC, the :ref:`CONFIG_FREERTOS_UNICORE` configuration is always set. .. _freertos-applications: ESP-IDF FreeRTOS Applications ----------------------------- Unlike Vanilla FreeRTOS, users must not call :cpp:func:`vTaskStartScheduler`. Instead, ESP-IDF FreeRTOS is started automatically. The entry point is a user defined ``void app_main(void)`` function. - Typically, users would spawn the rest of their applications task from ``app_main``. - The ``app_main`` function is allowed to return at any point (i.e., before the application terminates). - The ``app_main`` function is called from the ``main`` task. The ``main`` task is one of multiple tasks that are automatically spawned by ESP-IDF during startup. These tasks are: .. only:: not CONFIG_FREERTOS_UNICORE .. list-table:: List of Tasks Created During Startup :widths: 25 25 5 50 :header-rows: 1 * - Task Name - Affinity - Priority - Description * - Main Task (``main``) - CPU0 - 1 - Task that simply calls ``app_main``. This task will self delete when ``app_main`` returns * - Idle Tasks (``IDLEx``) - CPU0 and CPU1 - 0 - Idle tasks created for (and pinned to) each CPU * - IPC Tasks (``ipcx``) - CPU0 and CPU1 - 24 - IPC tasks created for (and pinned to ) each CPU. IPC tasks are used to implement the IPC feature. See :doc:`/api-reference/system/ipc` for more details. .. only:: CONFIG_FREERTOS_UNICORE .. list-table:: List of Tasks Created During Startup :widths: 25 25 5 50 :header-rows: 1 * - Task Name - Affinity - Priority - Description * - Main Task (``main``) - CPU0 - 1 - Task that simply calls ``app_main``. This task will self delete when ``app_main`` returns * - Idle Tasks (``IDLEx``) - CPU0 and CPU1 - 0 - Idle task created for (and pinned to) each CPU .. note:: Low priority numbers denote low priority tasks. Task API -------- .. include-build-file:: inc/task.inc Queue API --------- .. include-build-file:: inc/queue.inc Semaphore API ------------- .. include-build-file:: inc/semphr.inc Timer API --------- .. include-build-file:: inc/timers.inc Event Group API --------------- .. include-build-file:: inc/event_groups.inc Stream Buffer API ----------------- .. include-build-file:: inc/stream_buffer.inc Message Buffer API ------------------ .. include-build-file:: inc/message_buffer.inc