USB stands for “Universal Serial Bus”. It is a new interface technology that has been gradually widely used in the PC field in recent years. The USB interface has the characteristics of faster transmission speed, hot plugging and connecting multiple devices. It has been widely used in various external devices. There are currently three types of USB interfaces: USB1.1, USB2.0 and USB3.0, as well as the USB Type-C connector that has appeared in recent years. Theoretically, the transmission speed of USB1.1 can reach 12Mbps/second, while USB2.0 can reach a speed of 480Mbps/second, and it is backward compatible with USB1.1.