================================================================================
                                样例使用说明
                             Sample Description
================================================================================
功能描述：
此样例演示了USART的DMA方式发送和接收数据，USART配置为115200，数据位8，停止位1，
校验位None，下载并运行程序后，通过上位机下发12个数据，例如0x1~0xC，则MCU会把接收
到的数据再次发送。

Function descriptions:
This sample demonstrates the USART data transmission and reception using the 
DMA method. The USART is configured with a baud rate of 115200, 8 data bits, 
1 stop bit, and no parity. After compiling and downloading the program to the 
MCU, when the host computer sends 12 data bytes (0x1 to 0xC), the MCU will 
send the received data back to the host computer.

================================================================================
测试环境：
测试用板：PY32F403_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: PY32F403_STK
MDK Version: 5.28
IAR Version: 9.20
GCC Version: GNU Arm Embedded Toolchain 10.3-2021.10

================================================================================
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115200；
4. 上位机发送12个数据，MCU会反馈同样的12个数据给上位机。

Example execution steps:
1. Compile and download the program to the MCU;
2. Connect the PC and STK board with a USB to TTL module. The connection 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 a serial debugging assistant on the PC and connect to the appropriate COM 
   port with the baud rate set to 115200;
4. The host computer sends 12 data bytes (0x1 to 0xC), and the MCU will send back 
   the same 12 data bytes to the host computer.

================================================================================
注意事项：

Notes:

================================================================================
