/**
@page RTC_Calendar RTC Calendar Example
@verbatim
******************** (C) COPYRIGHT 2017 STMicroelectronics *******************
* @file RTC/RTC_Calendar/readme.txt
* @author MCD Application Team
* @brief Description of the RTC Calendar example.
******************************************************************************
*
* Redistribution and use in source and binary forms, with or without modification,
* are permitted provided that the following conditions are met:
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* this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
* 3. Neither the name of STMicroelectronics nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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*
******************************************************************************
@endverbatim
@par Example Description
This example guides you through the different configuration steps by mean of HAL API
to ensure Calendar configuration using the RTC peripheral.
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 180 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.
LSE oscillator clock is used as RTC clock source. LSE oscillator clock usually
delivered by a 32.768 kHz quartz.
HAL_RTC_SetTime()and HAL_RTC_SetDate() functions are then called to initialize the
time and the date.
A key value is written in backup data register 0 to indicate if the RTC is already configured.
The RTC is in the backup (BKP) domain, still powered by VBAT when VDD is switched off,
so the RTC configuration is not lost if a battery is connected to the VBAT pin.
The program behaves as follows:
1. After startup the program checks the backup data register 0 value:
- BKP_DR0 value not correct: (RTC_BKP_DR0 value is not correct or has not yet
been programmed when the program is executed for the first time) the RTC is
configured.
- BKP_DR0 value correct: this means that the RTC is configured and the time
and date are displayed on Debugger.
2. When an External Reset occurs the BKP domain is not reset and the RTC configuration
is not lost, LED4 is ON.
3. When power on reset occurs:
- If a battery is connected to the VBAT pin: the BKP domain is not reset and
the RTC configuration is not lost, LED2 is ON.
- If no battery is connected to the VBAT pin: the BKP domain is reset and the
RTC configuration is lost.
@note LED3 turns ON when there is an error in initialization.
The current time and date are updated and displayed on the debugger in aShowTime
and aShowDate variables.
@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 needs to ensure that the SysTick time base is always set to 1 millisecond
to have correct HAL operation.
@note Care must be taken when HAL_RCCEx_PeriphCLKConfig() is used to select the RTC clock source; in this
case the Backup domain will be reset in order to modify the RTC Clock source, as consequence RTC
registers (including the backup registers) and RCC_BDCR register are set to their reset values.
@par Keywords
System, RTC, Calendar, Backup Domain, Reset
@par Directory contents
- RTC/RTC_Calendar/Inc/stm32f4xx_hal_conf.h HAL configuration file
- RTC/RTC_Calendar/Inc/stm32f4xx_it.h Interrupt handlers header file
- RTC/RTC_Calendar/Inc/main.h Main program header file
- RTC/RTC_Calendar/Src/stm32f4xx_it.c Interrupt handlers
- RTC/RTC_Calendar/Src/main.c Main program
- RTC/RTC_Calendar/Src/stm32f4xx_hal_msp.c HAL MSP module
- RTC/RTC_Calendar/Src/system_stm32f4xx.c STM32F4xx system clock configuration file
@par Hardware and Software environment
- This example runs on STM32F42xxx/STM32F43xxx devices.
- This example has been tested with STM324x9I-EVAL RevB evaluation board and can be
easily tailored to any other supported device and development board.
- STM324x9I-EVAL RevB Set-up
- Please ensure that jumper JP8 is in position 2-3 to connect 3V battery to VBAT pin.
@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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