Windows下STM32 USB虚拟串口驱动程序。本人经多次实验发现，必须在开发时，设置CDC的PID和VID两个参数与驱动程序中stmcdc.inf中的数字相同。否则，系统将不可识别STM32的USB口为串口。(STM32 USB virtual serial port driver under Windows. I have many experiments found that must be in development, set the CDC PID and VID, two parameters and the driver in the stmcdc.inf in the same number. Otherwise, the system will not recognize the STM32 port of the USB as the serial port.)