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83 lines
3.4 KiB
Plaintext
83 lines
3.4 KiB
Plaintext
/**
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@page FreeRTOS_Semaphore FreeRTOS Semaphore example
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@verbatim
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******************** (C) COPYRIGHT 2017 STMicroelectronics *******************
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* @file FreeRTOS/FreeRTOS_Semaphore/readme.txt
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* @author MCD Application Team
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* @brief Description of the FreeRTOS Semaphore example.
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******************************************************************************
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* @attention
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*
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* Copyright (c) 2017 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 semaphores with CMSIS RTOS API.
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This example creates two threads that toggle LEDs through a shared semaphore.
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The first thread which have the higher priority obtains the semaphore and
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toggle the LED1 each 200 ms. After 5 seconds it releases the semaphore and
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suspends itself. The low priority thread can execute now, it obtains the
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semaphore and resume execution of the first thread, as it has the higher
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priority the first thread will try to obtain the semaphore but it fails
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because the semaphore is already taken by the low
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priority thread, which will toggle the LED3 for 5 seconds before releasing
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the semaphore and begin a new cycle
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@note Care must be taken when using HAL_Delay(), this function provides accurate delay (in milliseconds)
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based on variable incremented in HAL time base ISR. This implies that if HAL_Delay() is called from
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a peripheral ISR process, then the HAL time base interrupt must have higher priority (numerically lower)
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than 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() function.
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@note The application needs to ensure that the HAL time base is always set to 1 millisecond to have correct
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HAL operation.
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@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.
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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, Semaphore, Priorities
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@par Directory contents
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- FreeRTOS/FreeRTOS_Semaphore/Inc/main.h Main program header file
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- FreeRTOS/FreeRTOS_Semaphore/Inc/stm32f4xx_hal_conf.h HAL Library Configuration file
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- FreeRTOS/FreeRTOS_Semaphore/Inc/stm32f4xx_it.h Interrupt handlers header file
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- FreeRTOS/FreeRTOS_Semaphore/Inc/FreeRTOSConfig.h FreeRTOS Configuration file
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- FreeRTOS/FreeRTOS_Semaphore/Src/main.c Main program
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- FreeRTOS/FreeRTOS_Semaphore/Src/stm32f4xx_it.c Interrupt handlers
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@par Hardware and Software environment
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- This example runs on STM32F446xx devices.
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- This example has been tested with STM32446E-EVAL 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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