usb 3.0 specification 规范文档

This document presents an overview of Universal Serial Bus 3.0 architecture and key concepts. USB 3.0 is similar to earlier versions of USB in that it is a cable bus supporting data exchange between a host computer and a wide range of simultaneously accessible peripherals. The attached peripherals share bandwidth through a host-scheduled protocol. The bus allows peripherals to be attached, configured, used, and detached while the host and other peripherals are in operation. USB 3.0 utilizes a dual-bus architecture that provides backward compatibility with USB 2.0. It provides for simultaneous operation of SuperSpeed and non-SuperSpeed (USB 2.0 speeds) information exchanges. This chapter is organized into two focus areas. The first focuses on architecture and concepts related to elements which span the dual buses. The second focuses on SuperSpeed specific architecture and concepts. Later chapters describe the various components and specific requirements of SuperSpeed USB in greater detail. The reader is expected to have a fundamental understanding of the architectural concepts of USB 2.0. Refer to the Universal Serial Bus Specification, Revision 2.0 for complete details.