/**
@page RTC_Calendar RTC example
@verbatim
******************************************************************************
* @file Examples_LL/RTC/RTC_Calendar/readme.txt
* @author MCD Application Team
* @brief Description of the RTC 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 of the LL API to set the RTC calendar. The peripheral initialization uses LL unitary service
functions for optimization purposes (performance and size).
In this example, after start-up, SYSCLK is configured to the max frequency using the PLL with
HSE as clock source.
The RTC peripheral configuration is ensured by the Configure_RTC() function
(configure 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 LSE oscillator clock is used as RTC clock source by default.
The user can use also LSI as RTC clock source. The user uncomment the adequate
line on the main.c file.
@code
#define RTC_CLOCK_SOURCE_LSE
/* #define RTC_CLOCK_SOURCE_LSI */
@endcode
LSI oscillator clock is delivered by a 32 kHz RC.
LSE (when available on board) is delivered by a 32.768 kHz crystal.
Configure_RTC_Calendar function is then called to initialize the
time and the date.
A key value is written in backup data register 1 to indicate if the RTC is already configured.
The RTC is in the backup (BKP) domain. It means that when LSE is enabled, even after a reset
done with debugger, RTC configuration is not lost.
The program behaves as follows:
1. After startup the program checks the backup data register 1 value:
- BKP_DR1 value not correct: (value is not correct or has not yet
been programmed when the program is executed for the first time) the RTC is
configured.
- BKP_DR1 value correct: this means that the RTC is configured and the time
and date are displayed on Debugger.
2. When a reset (except power on reset) occurs the BKP domain is not reset and the RTC
configuration is not lost.
3. When power on reset occurs:
- On Nucleo board, as there are no battery connected to the VBAT pin:
the BKP domain is reset and the RTC configuration is lost.
LED1 is turned ON when the RTC configuration is done correctly.
The current time and date are updated and displayed on the debugger in aShowTime
and aShowDate variables (watch or live watch).
- LED3 is toggling : This indicates that the system generates an error.
@par Keywords
System, RTC, Calendar, Backup Domain, Reset
@Note<74>If the user code size exceeds the DTCM-RAM size or starts from internal cacheable memories (SRAM1 and SRAM2),that is shared between several processors,
<20><><A0><A0><A0>then it is highly recommended to enable the CPU cache and maintain its coherence at application level.
<0A><><A0><A0><A0><A0>The address and the size of cacheable buffers (shared between CPU and other masters) must be properly updated to be aligned to cache line size (32 bytes).
@Note It is recommended to enable the cache and maintain its coherence, but depending on the use case
<0A><><A0><A0><A0> It is also possible to configure the MPU as "Write through", to guarantee the write access coherence.
<0A><><A0><A0><A0><A0>In that case, the MPU must be configured as Cacheable/Bufferable/Not Shareable.
<0A><><A0><A0><A0><A0>Even though the user must manage the cache coherence for read accesses.
<0A><><A0><A0><A0><A0>Please refer to the AN4838 <20>Managing memory protection unit (MPU) in STM32 MCUs<55>
<0A><><A0><A0><A0><A0>Please refer to the AN4839 <20>Level 1 cache on STM32F7 Series<65>
@par Directory contents
- RTC/RTC_Calendar/Inc/stm32f7xx_it.h Interrupt handlers header file
- RTC/RTC_Calendar/Inc/main.h Header for main.c module
- RTC/RTC_Calendar/Inc/stm32_assert.h Template file to include assert_failed function
- RTC/RTC_Calendar/Src/stm32f7xx_it.c Interrupt handlers
- RTC/RTC_Calendar/Src/main.c Main program
- RTC/RTC_Calendar/Src/system_stm32f7xx.c STM32F7xx system source file
@par Hardware and Software environment
- This example runs on STM32F767xx devices.
- This example has been tested with NUCLEO-F767ZI 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
*/
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