STM32CubeF4/Projects/STM32446E_EVAL/Applications/FreeRTOS/FreeRTOS_Mutexes/readme.txt

/**
  @page FreeRTOS_Mutexes FreeRTOS Mutexes example
 
  @verbatim
  ******************** (C) COPYRIGHT 2017 STMicroelectronics *******************
  * @file    FreeRTOS/FreeRTOS_Mutexes/readme.txt
  * @author  MCD Application Team
  * @brief   Description of the FreeRTOS Mutexes example.
  ******************************************************************************
  * @attention
  *
  * <h2><center>&copy; Copyright (c) 2017 STMicroelectronics International N.V. 
  * All rights reserved.</center></h2>
  *
  * Redistribution and use in source and binary forms, with or without 
  * modification, are permitted, provided that the following conditions are met:
  *
  * 1. Redistribution of source code must retain the above copyright notice, 
  *    this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright notice,
  *    this list of conditions and the following disclaimer in the documentation
  *    and/or other materials provided with the distribution.
  * 3. Neither the name of STMicroelectronics nor the names of other 
  *    contributors to this software may be used to endorse or promote products 
  *    derived from this software without specific written permission.
  * 4. This software, including modifications and/or derivative works of this 
  *    software, must execute solely and exclusively on microcontroller or
  *    microprocessor devices manufactured by or for STMicroelectronics.
  * 5. Redistribution and use of this software other than as permitted under 
  *    this license is void and will automatically terminate your rights under 
  *    this license. 
  *
  * THIS SOFTWARE IS PROVIDED BY STMICROELECTRONICS AND CONTRIBUTORS "AS IS" 
  * AND ANY EXPRESS, IMPLIED OR STATUTORY WARRANTIES, INCLUDING, BUT NOT 
  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A 
  * PARTICULAR PURPOSE AND NON-INFRINGEMENT OF THIRD PARTY INTELLECTUAL PROPERTY
  * RIGHTS ARE DISCLAIMED TO THE FULLEST EXTENT PERMITTED BY LAW. IN NO EVENT 
  * SHALL STMICROELECTRONICS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, 
  * OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF 
  * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING 
  * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
  * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
  ******************************************************************************
  @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 board's LEDs can be used to monitor the example status:
  - LED1, LED2 and LED4 should toggle when the example 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 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 example runs on STM32F446xx devices.
  
  - This example has been tested with STM32446E-EVAL 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 example

 * <h3><center>&copy; COPYRIGHT STMicroelectronics</center></h3>
 */