Universal Serial Bus - USB Historical Perspective The Universal Serial Bus was originally developed in 1995 by a group of industry leading companies Compaq, Hewlett Packard, Intel, Lucent, Microsoft, NEC and Philips were involved in USB 2 developments USB defines an external expansion bus which makes adding peripherals to a PC relatively easy See:

Universal Serial Bus - USB Historical Perspective Major goals of USB 1.0 were ease-of-use and low cost USB version 1 was not designed to be a high speed bus – it’s for mice, keyboards, printers, scanners etc. In 2006, Intel estimated that over 3.5 billion USB interfaces had shipped NB that may include 2-10 “interfaces” per PC!

Universal Serial Bus - USB USB Connections The external expansion architecture of USB is shown below, which highlights: PC host controller hardware and software Robust connectors and cable assemblies “Peripheral friendly” master-slave protocols Expandable through multi-port hubs

Universal Serial Bus - USB Role of USB h/w and s/w Uniform view of I/O system for all application software Hides hardware implementation details Manages the dynamic attachment and detachment of peripherals “Enumeration” – initial communication with peripherals to discover device and driver identity Unique “address” for each peripheral Host PC software incorporates attached peripherals into the system power management scheme

Universal Serial Bus - USB Role of USB1.1 Hubs Provides additional, bi-directional connectivity for USB peripherals and works as bi-directional repeater Provides managed power to attached peripherals Recognises dynamic attachment of a peripheral Provides power during initialisation and later (0.5W to 2.5W max) May be cascaded up to five levels deep Monitors signals and handles transactions addressed to itself Supports 12Mbps (full-speed) and 1.5Mbps (low-speed) peripherals

Universal Serial Bus - USB USB1.1 Peripherals All USB peripherals are uniform slave devices that obey a defined protocol Peripherals respond to control transactions which may request detailed information about the device may request device configuration information may allocate a device ID Peripherals send and receive data to/from the host using a standard USB data format Standardized data movement to/from the PC host gives USB great flexibility and simplicity

Universal Serial Bus - USB USB 2.0 Same cables, same software interfaces, full support for USB1.1 devices Plus support for high-speed devices up to 480Mbits/sec Hub complexity increased to handle situations intelligently Became available some time after mid-2000

Universal Serial Bus - USB Wireless USB High speed personal wireless interconnect technology Connects up to 127 devices Up to 480Mbps at 3 metres Up to 110Mbps at 10 metres Based on the WiMedia Alliance “ultra-wideband common radio platform” See B.pdf B.pdf

Universal Serial Bus - USB USB 3.0 Released: End of 2008 USB 3.0 Promoters Group members: Intel, Microsoft, Hewlett-Packard, Texas Instruments, NEC and NXP Semiconductors Products started arriving in early Gbps (625MB/s), originally intended to be an optical and copper connection, backwards compatible with USB2 Actually just a copper connection – cheaper and easier to make than optical No one expected copper cabling to support 4.8Gbps in full duplex mode (USB 2 is only half-duplex) More energy efficient protocols and transmission than USB2

Universal Serial Bus - USB USB On-The-Go Normally, communication is controlled by a PC There is no way to connect peripherals together without the PC The USB On-The-Go (OTG) initiative specifies some additional capabilities to USB2.0 It adds some host capabilities to USB peripherals for direct interconnection Makes USB a bit more like FireWire See

Universal Serial Bus - USB Why USB? Changes to PC design are reducing internal expansion capability Ease of use – relatively simple for the user Better than existing connectors (2S/1P…) Good backwards compatibility, protecting investments Supported by many platforms (phones, CD players…) Single standard for manufacturers Design time will be reduced after initial learning period, broadens market Cost to manufacturers reduced by standardisation but initially raised by added complexity See: