Darrel CrossJeff Singer

Sabrina Thornton

What is USB?USB stands for Universal Serial BusProvides an expandable, fast, bi-directional,

low cost, hot pluggable Plug and Play serial hardware interface

Allows users to connect a wide variety of peripherals to a computer and have them automatically configured and ready to use

Implemented to provide a replacement for legacy ports to make the addition of peripheral devices quick and easy for the end user

History of USBDeveloped and standardized by a group of

leading companies from the computer and electronics industries in 1995

USB specifications were developed by Compaq, DEC, IBM, Intel , Microsoft, and NEC, joined later by HP, Lucent, and Phillips

These companies formed the USB Implementers Forum as a non-profit to publish specifications and provide a support organization and forum for the advancement and adoption of USB technology

History of USBThere have been three versions released

prior to 3.0USB 1.0 in January 1996 – data rates of 1.5

Mbps and 12 MbpsUSB 1.1 in September 1998 – first widely used

version of USBUSB 2.0 in April 2000

Major feature revision was the addition of a high speed transfer rate of 480 Mbps

Important note – all versions are backwards compatible with previous versions of USB

Key FeaturesSingle connector type

Replaces all different legacy connectors with one well-defined standardized USB connector for all USB peripheral devices

Hot swappableDevices can be safely plugged and unplugged as

needed while the computer is running (no need to reboot)

Plug and PlayOS software automatically identifies, configures,

and loads the appropriate driver when connection is made

Key FeaturesHigh performance

USB offers data transfer speeds at up to 480 MbpsExpandability

Up to 127 different peripheral devices may theoretically be connected to a single bus at one time

Bus-supplied powerUSB distributes the power to all connected

devices, eliminating the need for an external power source for low power devices (flash drives, memory cards, Bluetooth)

Key FeaturesEasy to use

The single standard connector type simplifies the end user’s task of figuring out what plug goes into what socket

Automatic driver loading does all the work for the end user

Low costThe host handles most of the protocol

complexity, making the design simple and having a low cost

USB NowThe next generation of USB hardware and

specifications is USB 3.0Version was announced by Pat Gelsinger at the

Intel Developer Forum in September 2007USB 3.0 Promoter Group announced in

November 2008 that version 1.0 has been completed

Now transitioning to the USB Implementers Forum, which essentially means it opens the specifications for hardware developers for implementation in future products

USB 3.0Upgrade from USB 2.0

Backwards compatibleNicknamed SuperSpeed USB because of the

significant speed improvements over existing USB specifications

New communication protocols for devicesNew transfer modesNew power management featuresLonger maximum cable lengthsSimilar to PCI Express 2.0 technology

Why the upgrade?Mainly the need for faster transfer rates in

devices such as hard drives, flash card readers, and DVD, Blu-ray, and HD DVD optical drives

User applications demanding a higher performance connection between the PC and peripherals

Need for greater energy efficiency in today’s “greener world”

USB 2.0 vs. USB 3.0 – HardwareUSB 2.0 USB 3.0Cable is thinnerHas 4 primary

conductorsHalf duplex data transfer

mode

Cable resembles an Ethernet cord by thickness

Has 8 primary conductorsThree twisted signal

pairs for data paths and one power pair

Full duplex data transfer mode

USB 2.0 vs. USB 3.0

USB 2.0 vs. USB 3.0

USB 2.0 vs. USB 3.0A side note on the USB 3.0 cable:

Even though the USB 3.0 specifications are designed for backwards compatibility with USB 2.0, the USB 3.0 cables are not compatible with the regular USB 2.0 connector

USB 2.0 vs. USB 3.0Proposed plug and receptacle compatibility

Receptacle Plugs accepted

USB 2.0 Standard-A

USB 2.0 Standard-A or USB 3.0 Standard-A

USB 3.0 Standard-A

USB 3.0 Standard-A or USB 2.0 Standard-A

USB 2.0 Standard-B

USB 2.0 Standard-B

USB 3.0 Standard-B

USB 3.0 Standard- B or USB 2.0 Standard-B

USB 3.0 Powered-B

USB 3.0 Powered-B, USB 3.0 Standard-B, or USB 2.0 Standard-B

USB 2.0 Micro-B USB 2.0 Micro-B

USB 3.0 Micro-B USB 3.0 Micro-B or USB 2.0 Micro-B

USB 2.0 Micro-AB

USB 2.0 Micro-B or USB 2.0 Micro-A

USB 3.0 Micro-AB

USB 3.0 Micro-B, USB 3.0 Micro-A, USB 2.0 Micro-B, or USB 2.0 Micro-A

Characteristic USB 2.0 USB 3.0

Data Rate Low-Speed (1.5 Mbps), Full-Speed (12 Mbps), and High Speed (480 Mbps)

SuperSpeed - about 5.0 Gbps

Data Interface Half-duplex two-wire differential signaling, unidirectional data flow with negotiated directional bus transitions

Dual-simplex, four-wire differential signaling separate from USB 2.0 signaling; simultaneous bi-directional data flows (Full Duplex)

Cable Signal Count Two for low-speed/full-speed/high-speed data path

Six – four for SuperSpeed data path, two for non-SuperSpeed data path

Bus Transaction Protocol

Host directed, polled traffic flow; packet traffic is broadcast to all devices

Host directed, asynchronous traffic flow; packet traffic is explicitly routed

Power Management Port-level suspend with two levels of entry/exit latency,device–level power management

Multi-level link power management supporting idle, sleep, and suspend states

Bus Power Support for low/high bus-powered devices with lower power limits for un-configured and suspended devices

Same as USB 2.0 with a 50% increase for un-configured power and 80% increase for configured power, about 900 milliamps

Port State Port hardware detects connect events; system software uses port commands to transition the port into an enable state (i.e., can do USB data communications flows)

Port hardware detects connect events and brings the port into operational state ready for SuperSpeed data communications

USB 3.0 vs. Other StandardsFireWire 800 has a maximum data transfer

rate of 800 MbpseSATA bus a a maximum data transfer rate of

3.2 GbpsExample:

Intel demonstrated transfer of a 25 GB HD movie in 70 seconds using a USB 3.0 bus versus the USB 2.0 transfer time of about 4 hours

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demonstrates-usb-3-0.arshttp://news.zdnet.com/2100-9595_22-262047.htmlhttp://arstechnica.com/hardware/news/2008/11/usb-3-0-

specification-finalized-devices-in-2010.arshttp://www.usb.orghttp://techon.nikkeibp.co.jp/english/NEWS_EN/20090310/166949/http://www.reghardware.co.uk/2008/01/09/ces_usb_3_revealed/http://arstechnica.com/old/content/2007/09/intel-announces-

demonstrates-usb-3-0.arshttp://en.wikipedia.org/wiki/Usbhttp://news.cnet.com/8301-17938_105-9780794-1.htmlhttp://thefutureofthings.com/news/5739/25gb-in-70-seconds-with-

usb-3-0.htmlhttp://www.intel.com/pressroom/archive/releases/20080813corp.htm