USB is a very popular serial interface especially for PCs. As well known, the interface is used to connect to a PC such equipments as a keyboard, a mouse, a printer, a Flash memory, a hard disk drive, a speaker, and so on.
USB has several speed versions, Low-Speed (1.5Mbps), Full-Speed (12Mbps), High-Speed (480Mbps) and so on.Toshiba TX03 series microprocessors support USB Full-Speed. A hierarchical structure is applied to USB interface. One “Host” dominates many “Devices” in a network. For example, a PC is a Host, and Devices are any apparatuses which are connected to the PC through USB cables, like a keyboard, a mouse and so on.