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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USART的自动波特率检测功能，调试助手发送一个字符0x7F，MCU反馈字符
串：Auto BaudRate Test。

Function descriptions:
This sample demonstrates automatic baud rate detection function of the USART.
The serial assistant sends a character 0x7F, the MCU feedback character
string: Auto BaudRate Test.
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测试环境：
测试用板：PY32M031_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: PY32M031_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. 通过USB转TTL模块连接PC与STK板,STK板与USB转TTL模块的连线方式如下；
STK板        USB转TTL模块
PA02(TX) --> RX
PA03(RX) --> TX
GND      --> GND
3. PC端打开串口调试助手，正确连接上通讯COM口，波特率设置为9600；
4. 调试助手发送一个字符0x7F，MCU反馈字符串：Auto BaudRate Test；

Example execution steps:
1. compile and download the program to MCU and run it;
2. Connect the PC to the STK board through the USB-to-TTL module. The connection 
method between the STK board and the USB-to-TTL module is as follows.
STK board    USB-to-TTL module
PA02(TX) --> RX
PA03(RX) --> TX
GND      --> GND
3. Open the serial assistant on the PC, correctly connect to the COM port, and 
set the baud rate to 9600. 
4. The serial assistant sends a character 0x7F, MCU feedback string: Auto 
BaudRate Test
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注意事项：
1. 不注释掉宏AUTO_BAUD_MODE0(main.c中)，上位机发送1字节的波特率检测0x7f，如果
MCU检测成功,返回字符：Auto BaudRate Test
2. 注释掉宏AUTO_BAUD_MODE0(main.c中)，上位机发送1字节的波特率检测0x55，如果MCU
检测成功，返回字符：Auto BaudRate Test

Notes:
1. Do not mask the macro AUTO_BAUD_MODE0(main.c), the host computer sends 1 byte
data(0x7f) and performs baud rate detection.if the MCU detection is successful, 
return characters: Auto BaudRate Test 
2. Mask the macro AUTO_BAUD_MODE0(main.c), the host computer sends 1 byte data
(0x55) and performs baud rate detection.if the MCU detection is successful, 
return characters: Auto BaudRate Test 
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