/**
@page FreeRTOS_Mutexes FreeRTOS Mutexes application
@verbatim
******************** (C) COPYRIGHT 2017 STMicroelectronics *******************
* @file FreeRTOS/FreeRTOS_Mutexes/readme.txt
* @author MCD Application Team
* @brief Description of the FreeRTOS Mutexes application.
******************************************************************************
* @attention
*
* Copyright (c) 2017 STMicroelectronics.
* All rights reserved.
*
* This software is licensed under terms that can be found in the LICENSE file
* in the root directory of this software component.
* If no LICENSE file comes with this software, it is provided AS-IS.
*
******************************************************************************
@endverbatim
@par Application Description
How to use mutexes with CMSIS RTOS API.
This application creates three threads, with different priorities, that access the
same mutex, as described below:
MutexHighPriorityThread() has the highest priority so executes
first and grabs the mutex and sleeps for a short period to let the lower
priority threads execute. When it has completed its demo functionality
it gives the mutex back before suspending itself.
MutexMeduimPriorityThread() attempts to access the mutex by performing
a blocking 'wait'. This thread blocks when the mutex is already taken
by the high priority thread. It does not unblock until the highest
priority thread has released the mutex, and it does not actually run until
the highest priority thread has suspended itself.
When it eventually does obtain the mutex all it does is give the mutex back
prior to also suspending itself. At this point both the high and medium
priority threads are suspended.
MutexLowPriorityThread() runs at the idle priority. It spins round
a tight loop attempting to obtain the mutex with a non-blocking call. As
the lowest priority thread it will not successfully obtain the mutex until
both high and medium priority threads are suspended. Once it eventually
does obtain the mutex it first resume both suspended threads prior to giving
the mutex back - resulting in the low priority thread temporarily inheriting
the highest thread priority.
Add the following variables to LiveWatch, these variables must remain equals all the time:
- HighPriorityThreadCycles
- MediumPriorityThreadCycles
- LowPriorityThreadCycles
STM32 Eval boards LEDs can be used to monitor the application status:
- LED1, LED2 and LED4 should toggle when the application runs successfully.
- LED3 is ON when any error occurs.
@note Care must be taken when using HAL_Delay(), this function provides accurate delay (in milliseconds)
based on variable incremented in HAL time base ISR. This implies that if HAL_Delay() is called from
a peripheral ISR process, then the HAL time base interrupt must have higher priority (numerically lower)
than the peripheral interrupt. Otherwise the caller ISR process will be blocked.
To change the HAL time base interrupt priority you have to use HAL_NVIC_SetPriority() function.
@note The application needs to ensure that the HAL time base is always set to 1 millisecond to have correct
HAL operation.
@note The FreeRTOS heap size configTOTAL_HEAP_SIZE defined in FreeRTOSConfig.h is set according to the OS resources memory requirements of the application with +10% margin and rounded to the upper Kbyte boundary.
For more details about FreeRTOS implementation on STM32Cube, please refer to UM1722 "Developing Applications
on STM32Cube with RTOS".
@par Keywords
RTOS, FreeRTOS, Threading, Mutexes
@par Directory contents
- FreeRTOS/FreeRTOS_Mutexes/Inc/main.h Main program header file
- FreeRTOS/FreeRTOS_Mutexes/Inc/stm32f4xx_hal_conf.h HAL Library Configuration file
- FreeRTOS/FreeRTOS_Mutexes/Inc/stm32f4xx_it.h Interrupt handlers header file
- FreeRTOS/FreeRTOS_Mutexes/Inc/FreeRTOSConfig.h FreeRTOS Configuration file
- FreeRTOS/FreeRTOS_Mutexes/Src/main.c Main program
- FreeRTOS/FreeRTOS_Mutexes/Src/stm32f4xx_it.c Interrupt handlers
@par Hardware and Software environment
- This application runs on STM32F42xxx/STM32F43xxx devices
- This application has been tested with STM324x9I-EVAL RevB evaluation board and can be
easily tailored to any other supported device and development board.
@par How to use it ?
In order to make the program work, you must do the following :
- Open your preferred toolchain
- Rebuild all files and load your image into target memory
- Run the application
*/
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