说明：  使用STM32F1或F4的开发板进行USB虚拟串口程序改造，必须在Windows上安装相应驱动。usbser.sys 复制到C:\Windows\System32\drivers, mdmcpq.inf 复制到C:\Windows\inf
(The use of STM32F1 or F4 development board for USB virtual serial port program transformation, you must install the corresponding drive on the Windows. Usbser.sys copied to C:\Windows\System32\drivers, and mdmcpq.inf copied to C:\Windows\inf)