Just Added: USB Superspeed Videos
USB 3.0 Introduction
The Need for Speed
The maximum theoretical speed for USB 2.0 is 480Mbps. Today's storage needs are increasing and with the larger storage sizes comes the need for higher bandwidth. A competing external technology, eSATA, was introduced as part of the SATA specification. It's maximum speed is 3.0Gbps making it a much faster solution. Motherboards and laptops started carrying these ports, but it still did not catch on with the general market. The USB-IF saw an oppty to introduce a new USB technology that was faster and carried the famous USB name, and called it USB Superspeed which offered speeds of up to 5.0 Gbps. It is also backwards compatible with prior USB devices and speeds. It supports continuous bursting and stream for Bulk protocols.
A lack of efficiency
One of the major complaints about USB 2.0 is it's lack of efficiency. This is what typically drove the bandwith down from the theoretical 480Mps. Things like PINGs, ACKs, NAKs, constant polling, and broadcasting to all enabled downstream ports. USB 2.0 is also a half-duplex broadcast bus. Superspeed is a dual-simplex unicast bus.
More error checking & recovery needed
In USB 2.0, transaction error detection and recovery and flow control only at the end to end level. In Superspeed its checked between the end to end and the link levels. There are CRC-5 and CRC-16 values that are checked by the different layers.
Training Videos for USB Superspeed
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USB Superspeed Link Training & Speed Negotiation We recommend viewing it full-screen |
USB Superspeed Device Enumeration We recommend viewing it full-screen |
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USB Superspeed Data Packet requests, etc. We recommend viewing it full-screen |
USB Link Flow Control We recommend viewing it full-screen |
Links:
USB Specification:
UASP (USB Attached SCSI):