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120 lines
5.7 KiB
Plaintext
120 lines
5.7 KiB
Plaintext
/**
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@page FreeRTOS_Mutexes FreeRTOS Mutexes example
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@verbatim
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******************************************************************************
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* @file FreeRTOS/FreeRTOS_Mutexes/readme.txt
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* @author MCD Application Team
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* @brief Description of the FreeRTOS Mutexes example.
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******************************************************************************
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* @attention
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*
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* Copyright (c) 2016 STMicroelectronics.
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* All rights reserved.
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*
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* This software is licensed under terms that can be found in the LICENSE file
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* in the root directory of this software component.
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* If no LICENSE file comes with this software, it is provided AS-IS.
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*
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******************************************************************************
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@endverbatim
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@par Application Description
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How to use mutexes with CMSIS RTOS API.
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This example creates three threads, with different priorities, that access the
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same mutex, as described below:
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MutexHighPriorityThread() has the highest priority so executes
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first and grabs the mutex and sleeps for a short period to let the lower
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priority threads execute. When it has completed its demo functionality
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it gives the mutex back before suspending itself.
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At that point, LED1 toggles.
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MutexMediumPriorityThread() attempts to access the mutex by performing
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a blocking 'wait'. This thread blocks when the mutex is already taken
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by the high priority thread. It does not unblock until the highest
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priority thread has released the mutex, and it does not actually run until
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the highest priority thread has suspended itself.
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When it eventually does obtain the mutex all it does is give the mutex back
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prior to also suspending itself.
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At this point both the high and medium priority threads are suspended and LED2 toggles.
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MutexLowPriorityThread() runs at the idle priority. It spins round
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a tight loop attempting to obtain the mutex with a non-blocking call. As
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the lowest priority thread it will not successfully obtain the mutex until
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both high and medium priority threads are suspended. Once it eventually
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does obtains the mutex, it first resumes both suspended threads prior to giving the mutex back,
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resulting in the low priority thread temporarily inheriting the highest thread priority.
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Add the following variables to LiveWatch, these variables must remain equals all the time:
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- HighPriorityThreadCycles
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- MediumPriorityThreadCycles
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- LowPriorityThreadCycles
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STM32 NUCLEO board's LEDs can be used to monitor the application status:
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- LED1, LED2 should toggle when the application runs successfully.
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- LED3 toggles when any error occurs.
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@note Care must be taken when using HAL_Delay(), this function provides accurate
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delay (in milliseconds) based on variable incremented in HAL time base ISR.
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This implies that if HAL_Delay() is called from a peripheral ISR process, then
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the HAL time base interrupt must have higher priority (numerically lower) than
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the peripheral interrupt. Otherwise the caller ISR process will be blocked.
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To change the HAL time base interrupt priority you have to use HAL_NVIC_SetPriority()
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function.
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@note The application needs to ensure that the HAL time base is always set to 1 millisecond
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to have correct HAL operation.
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@note The FreeRTOS heap size configTOTAL_HEAP_SIZE defined in FreeRTOSConfig.h is set accordingly to the
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OS resources memory requirements of the application with +10% margin and rounded to the upper Kbyte boundary.
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For more details about FreeRTOS implementation on STM32Cube, please refer to UM1722 "Developing Applications
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on STM32Cube with RTOS".
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@par Keywords
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RTOS, FreeRTOS, Threading, Mutexes
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@Note<74>If the user code size exceeds the DTCM-RAM size or starts from internal cacheable memories (SRAM1 and SRAM2),that is shared between several processors,
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<20><><EFBFBD><EFBFBD><EFBFBD>then it is highly recommended to enable the CPU cache and maintain its coherence at application level.
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<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>The address and the size of cacheable buffers (shared between CPU and other masters) must be properly updated to be aligned to cache line size (32 bytes).
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@Note It is recommended to enable the cache and maintain its coherence, but depending on the use case
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<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD> It is also possible to configure the MPU as "Write through", to guarantee the write access coherence.
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<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>In that case, the MPU must be configured as Cacheable/Bufferable/Not Shareable.
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<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Even though the user must manage the cache coherence for read accesses.
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<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Please refer to the AN4838 <20>Managing memory protection unit (MPU) in STM32 MCUs<55>
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<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Please refer to the AN4839 <20>Level 1 cache on STM32F7 Series<65>
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@par Directory contents
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- FreeRTOS/FreeRTOS_Mutexes/Src/main.c Main program
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- FreeRTOS/FreeRTOS_Mutexes/Src/stm32f7xx_hal_timebase_tim.c HAL timebase file
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- FreeRTOS/FreeRTOS_Mutexes/Src/stm32f7xx_it.c Interrupt handlers
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- FreeRTOS/FreeRTOS_Mutexes/Src/system_stm32f7xx.c STM32F7xx system clock configuration file
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- FreeRTOS/FreeRTOS_Mutexes/Inc/main.h Main program header file
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- FreeRTOS/FreeRTOS_Mutexes/Inc/stm32f7xx_hal_conf.h HAL Library Configuration file
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- FreeRTOS/FreeRTOS_Mutexes/Inc/stm32f7xx_it.h Interrupt handlers header file
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- FreeRTOS/FreeRTOS_Mutexes/Inc/FreeRTOSConfig.h FreeRTOS Configuration file
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@par Hardware and Software environment
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- This example runs on STM32F722xx/STM32F723xx/STM32F732xx/STM32F733xx devices.
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- This example has been tested with STM32F722ZE-Nucleo board and can be
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easily tailored to any other supported device and development board.
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@par How to use it ?
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In order to make the program work, you must do the following:
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- Open your preferred toolchain
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- Rebuild all files and load your image into target memory
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- Run the example
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*/
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