Universal Serial Bus，short for USB. It is a serial bus standard that connects computer systems and external devices, also it is a technical specification for input and output interface. It is widely used in personal computers and mobile devices, even expanded to other related fields such as photographic equipment, digital TV, game consoles, etc. The current USB3.1, transmission speed is 10Gbit/s, the three-stage voltage is 5V/12V/20V, and the maximum power supply is 100W.