/*!
    \file    main.c
    \brief   RTC calendar demo

    \version 2025-08-20, V3.3.2, demo for GD32F4xx
*/

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  This demo is based on the GD32f470z-EVAL-V1.0 board, it explains how 
to configure the RTC module. In this demo, RTC peripheral is configured to keep
time.
  
  The RTC clock source can be chose to LXTAL or IRC32K by uncomment the corresponding 
define in main file. And the HyperTerminal should be connected to the evaluation 
board via USART0. The vbat bin on the board should connect to the CR1220 battery.
  
  After start-up,get key value from BKP data register or bit RTCSRC of backup domain 
control register. If the value is not correct, the program will ask to set the time and 
alarm value on the HyperTerminal. If the key value is correct, the time will be displayed 
on the HyperTerminal.

  Then LED1 and LED2 is turned on.
  
  The RTC module is in the Backup Domain, and is not reset by the system reset or 
power reset. 
