USB4 Specification.zip(USB4.0原版资源合集)

This chapter presents an overview of Universal Serial Bus 4 (USB4™) architecture and key concepts. USB4 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. However, USB4 also allows a host computer to setup data exchange between compatible peripherals. The attached peripherals share bandwidth as configured by the host computer. The bus allows peripherals to be attached, configured, used, and detached while the host and other peripherals are in operation. When configured over a USB Type-C® connector interface, USB4 functionally replaces USB 3.2 while retaining USB 2.0 bus operating in parallel. Enhanced SuperSpeed USB, as defined in USB 3.2, remains the fundamental architecture for USB data transfer on a USB4 Fabric. The difference with USB4 versus USB 3.2 is that USB4 is a connection -oriented, tunneling architecture designed to combine multiple protocols onto a single physical interface, so that the total speed and performance of the USB4 Fabric can be dynamically shared. USB4 allows for USB data transfers to operate in parallel with other independent protocols specific to display, load/store and host-to-host interfaces. Additionally, USB4 extends performance beyond the 20 Gbps (Gen 2 x 2) of USB 3.2 to 40 Gbps (Gen 3 x 2) over the same dual-lane, dual-simplex architecture. This specification introduces the concept of protocol tunneling to USB bus architecture. Besides tunneling Enhanced SuperSpeed USB (USB3), display tunneling based on DisplayPort (DP) protocol and load/store tunneling based on PCI Express (PCIe) are defined. These protocol tunnels operate independently over the USB4 transport and physical layers. Additionally, USB4 allocates packets for bus configuration and management, and packe ts can be allocated specifically for host-to-host data connections.