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                                样例使用说明
                             Sample Description
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功能描述：
此样例演示通过RTC闹钟中断每隔1S左右将MCU从STOP模式下唤醒，每次唤醒会翻转LED，
LED翻转间隔为1s左右。

Function descriptions:
This sample demonstrates waking up the MCU from STOP mode approximately 
every 1 second using RTC alarm interrupt. Each time the MCU wakes up, 
the LED will toggle. The interval between LED toggling is also approximately 
1 second.
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测试环境：
测试用板：PY32T020_STK
MDK版本： 5.28
IAR版本： 9.20
GCC版本： GNU Arm Embedded Toolchain 10.3-2021.10

Test environment:
Test board: PY32T020_STK
MDK Version: 5.28
IAR Version: 9.20
GCC Version: GNU Arm Embedded Toolchain 10.3-2021.10
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使用步骤：
1. 编译并下载程序到MCU；
2. 断开swd连接线并重新上电;
3. 等待LED灯亮后，按下用户按键，LED灯关闭，进入STOP模式；
4. RTC开始计时，每隔1s左右就会通过闹钟中断唤醒MCU，并且翻转LED 。

Example execution steps:
1.Compile and download the program to the MCU;
2.Disconnect the SWD connection wire and power on again.
3.Wait for the LED to turn on, press the user button to turn off the LED 
and enter STOP mode;
4.The RTC starts counting, and approximately every 1 second, it will wake 
up the MCU through the alarm interrupt and toggle the LED.
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注意事项：
1，演示此样例功能时需要断开swd连接线并重新上电，因为默认情况下，仿真器会把
DBGMCU_CR.DBG_STOP置位。

Notes:
1.When demonstrating this sample, disconnect the SWD connection and 
power cycle the board, as the debugger will set DBGMCU_CR.DBG_STOP by default.
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