wenkong_junshi/Examples/BKP/Backup_data/readme.txt

/*!
    \file    readme.txt
    \brief   description of the backup data demo

    \version 2017-02-10, V1.0.0, firmware for GD32F30x
    \version 2018-10-10, V1.1.0, firmware for GD32F30x
    \version 2018-12-25, V2.0.0, firmware for GD32F30x
    \version 2020-09-30, V2.1.0, firmware for GD32F30x
*/

/*
    Copyright (c) 2020, GigaDevice Semiconductor Inc.

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are permitted provided that the following conditions are met:

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*/

  This demo is based on the GD32307C-EVAL-V1.1 board, it shows how to store user data 
in the backup data registers.
  As the backup domain still powered by VBAT when VDD is switched off, its contents
are not lost if a battery is connected to VBAT pin. 
  JP0 must be connected to 3.3V before the board is powered up, and LED3, LED4 and 
LED5 are on. After an external reset, LED3 and LED4 are off, LED5 is on. Change JP0 
connected to external battery, then execute a power-down and power-up operation, 
LED2, LED4 and LED5 are on.

  BT1 should have a 3.3V battery, JP0 can change the VBAT source.