wenkong_junshi/Examples/FWDGT/FWDGT_key/readme.txt

/*!
    \file    readme.txt
    \brief   description of the FWDGT_key example

    \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.

    Redistribution and use in source and binary forms, with or without modification, 
are permitted provided that the following conditions are met:

    1. Redistributions of source code must retain the above copyright notice, 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 the copyright holder 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 IMPLIED 
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 
IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, 
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NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 
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*/

  This demo is based on the GD32307C-EVAL-V1.1 board, it shows how to reload the 
FWDGT counter at regulate period using the EXTI interrupt. The FWDGT timeout 
is set to 1.6s (the timeout may varies due to IRC40K frequency dispersion).
 
  An EXTI is connected to a specific GPIO pin and configured to generate an interrupt
on its falling edge: when the EXTI Line interrupt is triggered (by pressing the tamper
key on the board), the corresponding interrupt is served. In the ISR, FWDGT counter is 
reloaded). 

  If the EXTI Line interrupt does not occur, the FWDGT counter is not reloaded before
the FWDGT counter reaches 00h, and the FWDGT reset. 

  There are three operation methods as follow:
  1.After the download is completed and the system is powered on, LED2 flashes once and 
then LED3 starts flashing.

  2.After the download is completed and the system is powered on, start to press the tamper 
button in quick succession, then LED2 is always on, and stop pressing the tamper button in
quick succession and LED3 starts to flash.

  3.After the download is completed and the system is powered on, LED2 flashes once and then 
LED3 starts flashing. At this time, after pressing the tamper button in rapid succession, 
LED3 is always on, and after stopping the rapid and continuous pressing of the tamper button,
LED3 starts flashing