本示例程序主要测试UART1的功能

当程序运行时，LCD屏显示：

STM32F10x DEMO

USART TEST

使用串口连接线将开发板和PC连接起来，打开PC上的串口调试软件并开启开发板连接对应的串口，

此时串口调试软件会收到：USART Example: USART-HyperTerminal communication。如果用串口

调试软件发送一个字符，开发板的LCD上显示接收到的字符串，接收满8个字符之后停止接收。

注意：波特率：9600；数据位：8（位）；结束位：1（位）。

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