94 lines
3.7 KiB
Plaintext
94 lines
3.7 KiB
Plaintext
/**
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@page HAL_TimeBase_RTC_ALARM HAL TimeBase RTC Alarm
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@verbatim
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******************** (C) COPYRIGHT 2017 STMicroelectronics *******************
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* @file HAL/HAL_TimeBase_RTC_ALARM/readme.txt
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* @author MCD Application Team
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* @brief Description of the HAL TimeBase RTC Alarm example.
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******************************************************************************
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* @attention
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*
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* <h2><center>© Copyright (c) 2017 STMicroelectronics.
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* All rights reserved.</center></h2>
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*
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* This software component is licensed by ST under BSD 3-Clause license,
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* the "License"; You may not use this file except in compliance with the
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* License. You may obtain a copy of the License at:
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* opensource.org/licenses/BSD-3-Clause
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*
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******************************************************************************
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@endverbatim
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@par Example Description
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How to customize HAL using RTC alarm as main source of time base,
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instead of Systick.
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The discovery board user button (connected to EXTI Line0) will be used
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to Suspend or Resume tick increment.
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Each time the user button is pressed; EXTI Line0 interrupt is generated and in the ISR
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the uwIncrementState is checked:
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1- If the uwIncrementState = 0: the tick increment is suspended by calling
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HAL_SuspendTick() API (RTC alarm interrupt is disabled).
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2- If the uwIncrementState = 1: the tick increment is Resumed by calling
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HAL_ResumeTick() API(RTC alarm interrupt is enabled).
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The alarm is configured to assert an interrupt when the RTC reaches 1 ms
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The example brings, in user file, a new implementation of the following HAL weak functions:
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HAL_InitTick()
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HAL_SuspendTick()
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HAL_ResumeTick()
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This implementation will overwrite native implementation in stm32f1xx_hal.c
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and so user functions will be invoked instead when called.
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The following time base functions are kept as implemented natively:
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HAL_IncTick()
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HAL_Delay()
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In an infinite loop, LED3 toggles spaced out over 500ms delay
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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 RTC Alarm time base is always set to 1 millisecond
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to have correct HAL operation.
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@par Directory contents
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- HAL/HAL_TimeBase_RTC_ALARM/Inc/stm32f1xx_hal_conf.h HAL configuration file
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- HAL/HAL_TimeBase_RTC_ALARM/Inc/stm32f1xx_it.h Interrupt handlers header file
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- HAL/HAL_TimeBase_RTC_ALARM/Src/stm32f1xx_it.c Interrupt handlers
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- HAL/HAL_TimeBase_RTC_ALARM/Src/main.c Main program
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- HAL/HAL_TimeBase_RTC_ALARM/Src/stm32f1xx_hal_timebase_rtc_alarm.c HAL time base functions
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- HAL/HAL_TimeBase_RTC_ALARM/Src/system_stm32f1xx.c STM32F1xx system clock configuration file
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@par Hardware and Software environment
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- This example runs on STM32F1xx devices.
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- This example has been tested with STMicroelectronics STM32VL-Discovery
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boards and can be easily tailored to any other supported device
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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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* <h3><center>© COPYRIGHT STMicroelectronics</center></h3>
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*/
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