/**
  @page FreeRTOS_Semaphore FreeRTOS Semaphore example
 
  @verbatim
  ******************** (C) COPYRIGHT 2014 STMicroelectronics *******************
  * @file    FreeRTOS/FreeRTOS_Semaphore/readme.txt
  * @author  MCD Application Team
  * @version V1.1.0
  * @date    18-June-2014 
  * @brief   Description of the FreeRTOS Semaphore example.
  ******************************************************************************
  *
  * Licensed under MCD-ST Liberty SW License Agreement V2, (the "License");
  * You may not use this file except in compliance with the License.
  * You may obtain a copy of the License at:
  *
  *        http://www.st.com/software_license_agreement_liberty_v2
  *
  * Unless required by applicable law or agreed to in writing, software 
  * distributed under the License is distributed on an "AS IS" BASIS, 
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  *
  ******************************************************************************
  @endverbatim

@par Description

This directory contains a set of source files that implement an example that
uses semaphores with CMSIS RTOS API 

This example creates two threads that toggle LED2 through a shared semaphore, 
as following:

The first thread which have the higher priority obtains the semaphore and 
toggle the LED2 each 200 ms. After 5 seconds it releases the semaphore and 
suspends itself. 

The low priority thread can execute now, it obtains the semaphore and 
resume execution of the first thread, as it has the higher priority 
the first thread will try to obtain the semaphore but it fails because 
the semaphore is already taken by the low priority thread, which will 
toggle the LED2 each 400 ms for 5 seconds before releasing the semaphore 
to begin a new cycle


@note Care must be taken when using HAL_Delay(), this function provides accurate
      delay (in milliseconds) based on variable incremented in SysTick ISR. This
      implies that if HAL_Delay() is called from a peripheral ISR process, then 
      the SysTick interrupt must have higher priority (numerically lower)
      than the peripheral interrupt. Otherwise the caller ISR process will be blocked.
      To change the SysTick interrupt priority you have to use HAL_NVIC_SetPriority() function.
      
@note The application need to ensure that the SysTick time base is always set to 1 millisecond
      to have correct HAL operation.

For more details about FreeRTOS implementation on STM32Cube, please refer to UM1722 "Developing Applications 
on STM32Cube with RTOS".


@par Directory contents

    - FreeRTOS/FreeRTOS_Semaphore/Src/main.c                Main program
    - FreeRTOS/FreeRTOS_Semaphore/Src/stm32l0xx_it.c        Interrupt handlers
    - FreeRTOS/FreeRTOS_Semaphore/Src/system_stm32l0xx.c    STM32L0xx system clock configuration file
    - FreeRTOS/FreeRTOS_Semaphore/Inc/main.h                Main program header file
    - FreeRTOS/FreeRTOS_Semaphore/Inc/stm32l0xx_hal_conf.h  HAL Library Configuration file
    - FreeRTOS/FreeRTOS_Semaphore/Inc/stm32l0xx_it.h        Interrupt handlers header file
    - FreeRTOS/FreeRTOS_Semaphore/Inc/FreeRTOSConfig.h      FreeRTOS Configuration file


@par Hardware and Software environment

  - This example runs on STM32L051xx, STM32L052xx, STM32L053xx STM32L062xx and 
    STM32L063xx device lines RevZ.
    
  - This example has been tested with STM32L053R8-Nucleo RevC 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>
 */
