51 lines
2.1 KiB
ReStructuredText
51 lines
2.1 KiB
ReStructuredText
.. _hooks_api_reference:
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FreeRTOS Hooks
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==============
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Overview
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--------
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FreeRTOS consists of Idle Hooks and Tick Hooks which allow for application
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specific funtiionality to be added to the Idle Task and Tick Interrupt. The
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ESP32 is dual core in nature, hence the ESP-IDF provides its own Idle and Tick
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Hooks that are dual core compatible in addition to the hooks provided by Vanilla
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FreeRTOS.
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Vanilla FreeRTOS Hooks
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----------------------
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Idle and Tick Hooks in vanilla FreeRTOS are implemented by defining
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implementations for the functions ``vApplicationIdleHook`` and
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``vApplicationTickHook`` respectively somewhere in the application. Vanilla
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FreeRTOS will run the user defined Idle Hook every iteration of the Idle Task,
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whereas the user defined Tick Hook will run once per tick interrupt (given that
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there are no pended ticks).
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Due to vanilla FreeRTOS being designed for single core, ``vApplicationIdleHook``
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and ``vApplicationTickHook`` will be run in both cores on the ESP32. In
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other words, the same Idle Hook and Tick Hook are used for both cores.
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To enable the vanilla FreeRTOS hooks in ESP-IDF, :ref:`CONFIG_FREERTOS_LEGACY_HOOKS`
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must be enabled in ``make menuconfig``. :ref:`CONFIG_FREERTOS_LEGACY_IDLE_HOOK`
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and :ref:`CONFIG_FREERTOS_LEGACY_TICK_HOOK` should also be enabled.
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ESP-IDF Idle and Tick Hooks
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---------------------------
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Due to the dual core nature of the ESP32, it may be necessary for some
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applications to have seperate Idle Hooks for each core. Furthermore, it may
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be necessary for Idle and Tick Hooks to have execute multiple functionalities
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that are configurable at run time. Therefore the ESP-IDF provides it's own Idle
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and Tick Hooks in addition to the hooks provided by Vanilla FreeRTOS.
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The ESP-IDF Hooks do not operate in the same way as Vanilla FreeRTOS Hooks
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where users provide a definition for each of the hooks. Instead, the ESP-IDF
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Hooks are predefined to call a list of user registered callbacks specific to
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each core. Users can register and deregister callbacks which are run on the
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Idle or Tick Hook of a specific core.
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API Reference
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-------------
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.. include:: /_build/inc/esp_freertos_hooks.inc |