使用STM32进行 USB虚拟串口(Slave)实验 ，这是在开发板上经过调试后的程序，可自行下载进行试验(Using STM32 for USB virtual serial port (Slave) experiment, which is in the development board after debugging procedures, can be downloaded for testing)

STM32F4基础应用程序和串口对应基础程序，程序代码为C语言，清晰易懂(STM32F4 basic application and serial corresponding basic program, program code is C language, clear and easy to understand)