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_ASSERT_ON_UNTESTED_FUNCTION` will trigger a halt in functions in ESP-IDF FreeRTOS that have not been fully tested in an SMP context.
-: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
