/**
  @page RTC_Alarm RTC Alarm Example
  
  @verbatim
  ******************** (C) COPYRIGHT 2016 STMicroelectronics *******************
  * @file    RTC/RTC_Alarm/readme.txt 
  * @author  MCD Application Team
  * @brief   Description of the RTC Alarm example.
  ******************************************************************************
  * @attention
  *
  * Copyright (c) 2016 STMicroelectronics.
  * All rights reserved.
  *
  * This software is licensed under terms that can be found in the LICENSE file
  * in the root directory of this software component.
  * If no LICENSE file comes with this software, it is provided AS-IS.
  *
  ******************************************************************************
  @endverbatim

@par Example Description 

Configuration and generation of an RTC alarm using the RTC HAL API.

At the beginning of the main program the HAL_Init() function is called to reset 
all the peripherals, initialize the Flash interface and the systick.
Then the SystemClock_Config() function is used to configure the system
clock (SYSCLK) to run at 48 MHz.

The RTC peripheral configuration is ensured by the HAL_RTC_Init() function.
This later is calling the HAL_RTC_MspInit()function which core is implementing
the configuration of the needed RTC resources according to the used hardware (CLOCK, 
PWR, RTC clock source and BackUp). You may update this function to change RTC configuration.

@note LSI oscillator clock is used as RTC clock source by default.
      The user can use also LSE as RTC clock source. The user uncomment the adequate 
      line on the main.h file.
      @code
        #define RTC_CLOCK_SOURCE_LSI  
        /* #define RTC_CLOCK_SOURCE_LSE */
      @endcode
      LSI oscillator clock is delivered by a 40 kHz RC.
      LSE (when available on board) is delivered by a 32.768 kHz crystal.

HAL_RTC_SetDate() and HAL_RTC_SetTime() functions are called to initialize the 
time and the date.
HAL_RTC_SetAlarm_IT() function is then called to initialize the Alarm feature with 
interrupt mode.

In this example, the Time is set to 02:20:00 and the Alarm must be generated after 
30 seconds on 02:20:30.

LED3 is turned ON when the RTC Alarm is generated correctly.
The current time is updated and displayed on the debugger in aShowTime variable.

In case of error, LED3 is toggled with a period of one second.

@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.

@par Directory contents 

  - RTC/RTC_Alarm/Inc/stm32f0xx_hal_conf.h    HAL configuration file
  - RTC/RTC_Alarm/Inc/stm32f0xx_it.h          Interrupt handlers header file
  - RTC/RTC_Alarm/Inc/main.h                  Header for main.c module  
  - RTC/RTC_Alarm/Src/stm32f0xx_it.c          Interrupt handlers
  - RTC/RTC_Alarm/Src/main.c                  Main program
  - RTC/RTC_Alarm/Src/stm32f0xx_hal_msp.c     HAL MSP module
  - RTC/RTC_Alarm/Src/system_stm32f0xx.c      STM32F0xx system source file


@par Hardware and Software environment

  - This example runs on STM32F042x6 devices.
  - This example has been tested with STMicroelectronics STM32F042K6-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



  */
