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93 lines
3.8 KiB
Plaintext
93 lines
3.8 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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* 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 Example Description
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This example describes how to customize the HAL time base using RTC alarm instead
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of Systick as main source of time base. The nucleo board user button (connected to EXTI Line13)
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will be used to Suspend or Resume tick increment.
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Each time the user button is pressed; EXTI Line13 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 timer 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 stm32f4xx_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, LED2 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 HAL time base is always set to 1 millisecond
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to have correct HAL operation.
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@par Keywords
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System, RTC Alarm, Time base, HAL
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@par Directory contents
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- HAL/HAL_TimeBase_RTC_ALARM/Inc/stm32f4xx_hal_conf.h HAL configuration file
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- HAL/HAL_TimeBase_RTC_ALARM/Inc/stm32f4xx_it.h Interrupt handlers header file
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- HAL/HAL_TimeBase_RTC_ALARM/Src/stm32f4xx_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/stm32f4xx_hal_timebase_rtc_alarm.c HAL time base functions
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- HAL/HAL_TimeBase_RTC_ALARM/Src/system_stm32f4xx.c STM32F4xx system clock configuration file
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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 STMicroelectronics STM32446E-Nucleo Rev C
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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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- For This example to work properly, a 2.2 <20>F Capacitor must be present on the board in slot C26.
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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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