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/**
@page HSEM_ReadLock HSEM ReadLock example
@verbatim
******************************************************************************
* @file HSEM/HSEM_ReadLock/readme.txt
* @author MCD Application Team
* @brief Description of the HSEM ReadLock example.
******************************************************************************
*
* Copyright (c) 2019 STMicroelectronics. All rights reserved.
*
* This software component is licensed by ST under BSD 3-Clause license,
* the "License"; You may not use this file except in compliance with the
* License. You may obtain a copy of the License at:
* opensource.org/licenses/BSD-3-Clause
*
******************************************************************************
@endverbatim
@par Example Description
How to enable, take then release semaphore using 2 different Process.
First, Enable HW semaphore using __HAL_RCC_HSEM_CLK_ENABLE macro.
Secondly, Semaphore 9 with Process1(ID=12) is locked in 2-step(Write) lock procedure.
==> LED2 is ON when lock with Process1 is done correctly.
Third, Lock the same semaphore 9 with Process1(ID 13) via the same semaphore 9 using 2-step(Write) lock procedure,
==> No lock is done, because the semaphore 9 is already locked. otherwise LED1 is ON.
Finally, semaphore 9 with Process1(ID=12) is released and take the same semaphore 9 with Process2(ID=13)
==> Check take status, if equal to 0, release done otherwise, LED1 is ON.
==> LED2 is ON, when lock with Process2 is done correctly.
In every step, if any mismatch with right result, LED1 is ON.
@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 example need to ensure that the SysTick time base is always set to 1 millisecond
to have correct HAL operation.
@par Keywords
Hardware semaphore, Semaphore, HSEM, synchronize, Lock, Unlock, Take, Release, Process
@par Directory contents
- HSEM/HSEM_ReadLock/Inc/stm32wbxx_hal_conf.h HAL configuration file
- HSEM/HSEM_ReadLock/Inc/stm32wbxx_it.h Interrupt handlers header file
- HSEM/HSEM_ReadLock/Inc/main.h Header for main.c module
- HSEM/HSEM_ReadLock/Src/stm32wbxx_it.c Interrupt handlers
- HSEM/HSEM_ReadLock/Src/stm32wbxx_hal_msp.c HAL MSP file
- HSEM/HSEM_ReadLock/Src/main.c Main program
- HSEM/HSEM_ReadLock/Src/system_stm32wbxx.c stm32wbxx system source file
@par Hardware and Software environment
- This example runs on STM32WB55RGVx device.
- This example has been tested with P-NUCLEO-WB55 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>© COPYRIGHT STMicroelectronics</center></h3>
*/
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