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                                样例使用说明
                                Sample Description
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功能描述：
此样例演示了在stop模式下，使用GPIO中断唤醒。

Function descriptions:
This sample demonstrates waking up from stop mode using GPIO interrupt.
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测试环境：
测试用板：PY32F002B_STK
MDK版本： 5.28
IAR版本： 9.20

Test environment:
Test board: PY32F002B_STK
MDK Version: 5.28
IAR Version: 9.20
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使用步骤：
1. 编译下载程序到MCU，并运行；
2. LED灯亮，按下按键，LED灯灭，进入stop模式；
3. 在PA06上产生一个下降沿，程序退出stop模式；
4. LED以200ms的间隔进行翻转。

Example execution steps:
1. compile and download the program to MCU and run it;
2. When the LED is on press the key,the LED goes off and enters stop mode;
3. generate a falling edge on PA06 and the program exits stop mode;
4. the LED are toggled in 200ms intervals.
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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。
2，注意关闭systick中断，防止该中断唤醒MCU。

Notes:
1. to demonstrate this sample function, you need to disconnect the swd connection
wire and re-power,because by default, the emulator will set the DBGMCU_CR.DBG_STOP.
2. Be careful to turn off the systick interrupt to avoid this interrupt waking up
the MCU.
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