USB - Wikipedia
`
`WIKIPEDIA
`
`Page | of29
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`USB
`
`
`USB,short for Universal Serial Bus, is an industry standard that was developed to define cables, connectors and protocols for
`connection, communication, and power supply between personal computers and their peripheral devices. ©!
`
`USB was designed to standardize the connection of computer peripherals (including keyboards, pointingdevices, digital cameras,
`printers, portablemediaplayers, disk drives and networkadapters) to personalcomputers, both to communicate and to supply electric
` and
`pawer.It has largely replaced interfaces such as serial ports
`elports, and has become commonplace on a wide rangeof devices.
`USB connectors have replaced other types for batterychargers ofportable devices.
`
`Released in 1996, the USB standard is currently maintained by the USBImplementersForum (USB IF).
`
`Universal Serial Bus (USB)
`
` 02280sti)
`
`Type
`
`Certified USB logo
`Bus
`Production history
`Designer
`Campaq, DEC,IBM,
`Intel, Microsoft, NEC,
`and Nortel
`
`4.5 mm (type-A)*!
`7.26 mm (type-B)
`10.44 mm (type-B
`SuperSpeed}
`4.8-3 mm
`(mini/micro}
`2.4 mm (type-C)
`Yes
`
`Yes
`
`4 wires plus shield
`9 wires plusshield
`
`(SuperSpeed)
`4:1 power, 2 data, 1
`ground
`5 (On-The-Go)
`9 (SuperSpeed)
`
`
`Contents
`January 1996
`_ Designed
`Overview
`Objectives
`i Produced_—Since May 1996"
`Limitations
`| Superseded Serial port, parallel
`History
`|
`part, gameport,
`Version history
`Apple Desktop Bus,
`Release versions
`PS/2 port, and
`Powerrelated specifications
`MagSafe
`USB 1.x
`USB 2.0
`Genera! specifications
`USB 3.x
`, Length
`2-5 m (6 ft 7 in-16
`System design
`i
`5 in) {by category)
`i
`Device classes
`12 mm (type-A)P
`USB massstorage / USB drive
`8.45 mm (type-B)
`Media Transfer Protocol
`Humaninterface devices
`6.8 mm (mini/micro)
`Device Firmware Upgrade
`8.25 mm (type-C)
`Connectors
`Connector properties
`Durability
`Campatibility
`Cannectortypes
`Standard connectors
`Mini connectors
`Micra connectors
`OMTPstandard
`USB 3.0 connectors and backward compatibility
`USB On-The-Go connectars
`USB-G
`Host and device interface receptacles
`Pinouts
`Praprietary cannectars and formats
`Colors
`Cabling
`Power
`USB Battery Charging
`Accessory charging adaptors (ACA)
`PowerDelivery (PD)
`Sleep-and-charge ports
`Mobile device charger standards
`In China
`OMTP/GSMA Universal Charging Salution
`EU smartphone powersupply standard
`Non-standard devices
`PoweredUSB
`Signaling (USB PHY)
`Signaling rate (transmission rate}
`Transaction latency
`Electrical specification
`Signaling state
`Line transition slate
`Line state (covering USB 1.x and 2.x)
`Transmission
`Transmission example on a USB1.1 full-speed device
`USB 2.0 speed negotiation
`USB 3.0
`
`Width
`
`Height
`
`Hot
`pluggable
`External
`
`| Cable
`
`1
`|
`|
`
`i
`
`Connector
`
`I
`:
`
`
`
`' Max.
`;
`_ current
`
`|
`
`|
`
`||
`
`SuperSpeed)
`
`11 {(Powered-B
`24(type-C)
`
`Unique
`Electrical
`5VDC
`5.00 GG+0.25
`5.00 “o's5 V (USB
`3.0)
`20,00 V (PD)
`0.5 A (USB 2.0)
`0.9 A (USB3.0)
`1.5 A (BC 1.2)
`
`https://en.wikipedia.org/wiki/USB
`
`HTC EXHIBIT 1033
`HTC America, Inc.v. VirginiaInnovation 1/7/2018
`Sciences, Inc.
`
`Page 1 of 30
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`IPR2017-000874
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`Page 1 of 30
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`IPR2017-000874
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`cS¥3 - Wikipedia
`
`Protocol layer
`Handshake packets
`Teken nackets
`OUT, IN, SETUP, and PING tckan packets
`SOF: Star-af-frame
`SSPLIT and OSPLIT: Start-soiit transaction and complete spit transaction
`Data packets
`PRE packet(tells hubs te temperarily switch to law speed mode)
`Transaction
`OUTtransaction
`IN transaction
`SETUPtransaction
`Setup packet
`Control transfer exchange
`Audio streaming
`Comparisons with other connection methods
`FireWire
`Ethernet
`MIDI
`eSATA/@SATApP
`Thunderbalt
`ate
`Interoperability
`Related standards
`See also
`fi
`References
`Further reading
`Externallinks
`
`Page 2 of 30
`
`3A Cype-C}
`Up toS A‘PD)
`Data
`Packet data, defined
`by specifications
`
`1 bit
`1.5; 12; 480; 5,000;
`10,000; 20,000 Mbit/s
`(depending on mode)
`
`127
`
`Serial
`Pin out
`USB
`
`«
`
`+ Bm
`12
`
`3
`
`'
`i
`F‘Data signal
`1
`3
`i
`|
`
`Width
`Bitrate
`
`Max.
`devices
`Protocol
`
`fewnds
`« De De
`a
`—
`
`=
`
`_
`oe
`The type-A plug (left) and type-B
`plug (right)
`[1] Vaus (45 V!
`[1 pate-
`Cl Data+
`[J Ground
`
`Pin 1
`Pin2
`Pin 3
`: Pin 4
`
`:!
`
` a|
`
`aie
`
`USB-A 3.* Gen1ports
`
`Overview
`
`Objectives
`The Universal Serial Bus was developed to simplify and improve the interface kerween personal computers andperipheral deviccs, when compared with previously existing standard
`or ad-hoc proprietaryinterfaces. !4l
`
`From the computer user's perspective, the USB interface improved ease of use in several ways. The USBinterface is self-configuring, so the user need not adjust settings on the
`device and interface for speed or data format, or configure interrupts, input/output addresses, or direct memory access channels. 15 USB connectorsare standardized al the host, so
`any peripheral can use any availabie socket. USB takes full advantage of the additional processing power that can be economically put inta peripheral devices so that they can
`manage themselves; USB devices often do not have user-adjuslable interface sellings. The USB interface is "hot pluggable", meaning devices can be exchanged without rebooting the
`host compuler. Small devices can be powered directly from the USB interface, displacing extra power supply cables. Because use of the USB logosis only permitted after compliance
`testing, the user can have confidence that a USB device will work as expected without extensive intcraction with scttings and configuration; the USBinterface defines protocols for
`recovery from commonerrors, improvingreliability over previousinterfaces. “4! Installation of a device relying on the USB standard requires minimal operator action. Whena device
`is plugged into a port on a running personal computer system,it is either entirely automatically configured using existing device drivers, or the system prompts the userto locate a
`driver which is theninstalled and configured automatically.
`
`For hardware manufacturers and software developers, the USB standard eliminates the requirementto develop proprietary interfaces to new peripherals. The wide range of transfer
`speeds available from a USBinterface suils devices ranging from keyboards and mice up to streamingvideo interfaces. A USB interface can be designed ta provide the best available
`latency fortime-critical functions, or can be set up to do backgroundtransfers of bulk data with little impact on system resources. The USB interface is generalized with no signal
`lines dedicated to only one function of one device. “
`
`Limitations
`USB cables are limited in length, as the standard was meant to counect lo peripherals on the same table-top, not between roomscr between buildings. However, a USB port can be
`connecled to a gateway that accesses distant devices. USB has a strict "tree" topology and "master-slave" protocol for addressing peripheral devices; peripheral devices cannot
`interact with one another except via the host, and two hosts cannot communicate over their USB ports directly. Someextension to this limitation is possible through "USB On The
`Go". A host cannot "broadcast" signals to all peripherals at once, cach rust be addressed individually. Some very high speed peripheral devices require sustained speeds not
`available in the USB standard. “ While converters exist between certain “legacy”interfaces and USB, they may not providefull implementation of the legacy hardware; for example,
`4 USB to parallel por: converter may workwell with a printer, but not with a scannerthat requires bi-directional use o¢ the data pins.
`
`https://en.wikipedia.org/wiki/USB
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`USB - Wikipedia
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`For a product developer, use of USB requires implementation of a complex protocol and implies an "intelligent" controllcr in the peripheral device. Developers of USB devices
`intended for public sale generally must obtain a USB ID which requires a fee paid to the Implementers’ Forum. Developers of products that use the USB specification must sign an
`agreement with Implementer's Forum. Useof the USB logos on the product require annual fees and membership in the organization. “!
`
`History
`
`
`
`
`
`Bi
`the
`head of a standard
`periaal oe ee
`
`i
`i
`The basic USB tridentlage!
`
`61
`
`A group of seven companies began the development of USB in 1994: Compaq, DEC, IBM,
`Intel, Microsoft, NEC, and Nortel. The goal was to make it fundamentally easier to connect
`external devices to PCs by replacing the multitude of connectorsat the back of PCs, addressing
`the usability issues of existing interfaces, and simplifying software configuration of all devices
`connected to USB, as well as permitting greater dala rates for external devices. A team
`including AjayBhatt worked on the standard at
`Intel;®!*!
`the first integratedcircuits
`supporting USB were producedby Intelin 1995.!"!
`The original USB 1.0 specification, which was introduced in January 1996, defined data
`transfer rates of 1.5 Mbit/s Low Speed and 19 Mbit/s Full Speed." Microsoft Windows 95,SR 2.1 provided OEM support for the
`devices. Thefirst widely used version of USB was 1.1, which was released in September 1998. The 12 Mbit/s data rate was intendedfor higher-speed devices such as disk drives, and
`the lower1.5 Mbit/s rate for low data rate devices such as joysticks." Apple,Ine,"s iMac wasthefirst mainstream product with USB and the iMac's success popularized USBitself"
`Following Apple's design decision to removeall legacyports fromthe iMac, many PC manufacturers beganbuilding legacy-freePCs, which led to the broader PC market using USB
`asa standard.!9114I051
`
`The USB 2.0 specification was released in April 2000 and wasratified by the USBImplementers Forum (USB-IF) at the end of 2001. Hewlett-Packard,Intel, LucentTechnologies
`(now Nokia), NEC, and Philips jointly led the initiative to develop a higher data transfer rate, with the resulting specification achieving 480 Mbit/s, 4o timesasfast as the original
`USB 1.1specification.
`
`The USB 3.9 specification was published an 12 November 2008.Its main goals were to increase the data transfer rate (up to 5 Ghit/s), decrease power consumption, increase pawer
`
`versionis also called SuperSpeed.""! Thefirst USB 3.0 equipped devices were presented in January2010, "9
`
`As of 2008,approximately6 billion USB ports and interfaces were in the global marketplace, and about2 billian were being sold each year,!*l
`The USB 3.1 specification was published in July 2013.
`
`In December 2014, USB-IF submitted USB 3.1, USB Power Delivery 2.0 and USBType-C specificationsto the IEC (TC_109 ~ Audio, video and multimedia systems and equipment)
`for inclusion in the international standard IEC 62680 Universal Serial Bus interfacesfor data and power, whichis currently based on USB2.0.74)
`
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`USB- Wikipedia
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`The USB 2.2 specification was published in September 2017.
`
`Version history
`
`Release versions
`
`| Releasename| Releasedate | Maximumtransferrate{|
`/uss08| Decembert9c4.)—=i<“‘é‘é~*CRTle
`|
`a April 1995
`:
`Prerelease re
`{
`j Use 99
`Prerelease
`
`oe _ Release Candidate
`| USE 4ORS
`
`USE 1.0
`
`Nate
`
`OO
`
`
`
`
`
` : SuperSpeed~ U0 Goi)
`
`Isc referred te assus34 Gen ta and USB 3.2Gen txt
`
`
`Also referred lo as USE3.1Gen 23 and USE3.2‘Gen xt
`
`
`i ahuly 2013
`i September 2017| SuperSpeed+ (29 Gbit/s)
`# Includes new USB 3,2 Gen 1x2 and USB 3.2 Gen 2x2 multi-linkedsCe
`
`Powerrelated specifications
`
`
`Note
`i Max. power
`; Release date
`Relaase nama
`{
`BV,
`
`1.54
`
`i} USB|Battery Charging 4 a i 2007 03
`
`
`i “2009404~15
`USB Battery Charging 4
`
`
`i “USBBattery Charging 4
`201g12-07
`PBV,5A
`uss.Power Dalivery revision 1.6 (\
`EQOVBA
`USB Power Delivery revision 4
`| USB Type-¢ 1.0
`
`i
`
`: Using sk pratocl over bus pawer(Veus)
`
`
`| New connectorand cable specication
`
`p r
`
`USE Power Delivery re.
`
`i|
`
`USB 1.x
`
`Released in January 1996, USB 1.0 specified data rates of 1.5 Mbit/s (Low Bandwidih or Low Speed) and 12 Mbit/s (Full Speed).It did notallowfor extension cables or pass-
`through monilors, due to timing and power limitations. Few USB devices madeit to the market until USB 1.1 was released in August 1998. USB 1.1 was the earliest revision that was
`widely adopted andled to what Microsoft designated the "Legacy-free PC".P Asis]
`Neither USB 1.0 nor 1.1 specified a design for any connector smaller than the standard type A or type B. Though manydesigns for a miniaturised type B connector appeared on many
`peripherals, conformance to the USB 1.x standard was fudged by treating peripherals that had miniature connectors as though they had a tethered connection (that is: no plug or
`socket at the peripheral and). There was no known minizture type A connector until USB 2.0 (rev 1.01) introduced one.
`
`USB 2.0
`
`Someof the mostsignificant items included in the change notic2sinclude:
`
`USB 2.0 was released in April 2000, adding a higher maximum signalingrate of 480 Mbit/s (High Speed or High Bandwidth), in
`addition to the USB 1.x Full Speed signaling rate of 12 Mbit/s. Due to bus access constraints, the effective throughput cf the High Speed
`signaling rateis limited to 280Mbit/sor 35 MB/s.?4l
`Modifications to the USB specification have been made via Engineering ChangeNotices (ECN). The mosl important of these ECNsare
`
`ttPiel
`
`The Hi-Speed USE logit
`
`included into the USB 2.0 specification package available from USB.org:”7)
`
`
`A USB 2.0 PC] expansion card
`
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`USB - Wikipedia
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`= Mini-A and Mini-B Connector
`= Micro-USB Cables and Connecicrs Specification 1.01
`=
`InterChipUSB Supplement
`= On-The-Go Supplement 1.3 USBOn-The-Go makesit possible for two USB devices to communicate with each other without requiring a separate USB host.
`" Battery Charging Specification 1.1 Added support for dedicated chargers , host chargers behaviorfor devices with dead batteries.
`= Battery Charging Specification 1.2:°" with increased current of 1.5 A on charging parts for unconfigured devices, allowing High Speed communication while having a current up
`to 1.5 A and allawing a maximum currentof 5 A.
`= Link Power Management Addendum ECN which adds a s/eep pawerstate.
`
`USB 3.x
`
`SUPERSPEED
`The USB 3.0 specification was released on 12 November 2008,withits managementtransferring f-om USB 3.0 Promoter Groupto the
`_=—-s
`USBImplementersForum(USB-IF),andannouncedon17November2008attheSuperSpeedUSBDevelopers Conference.™!
`CERTIFIED U
`USB3.0 adds a SuperSpeed transfer mode, with associated backward compatible plugs,receptacles, and cables. SuperSpeed plugs and
`So
`receptacles areidentifiedwithadistinctlogoandblueinsertsin standardformatreceptacles.
`The SuperSpeed mode provides a dat
` The SuperSpeed USB logo
`payload throughputis actually 4 Gbit/s, and the specification considers it reasonable to achieve about 3.2 Gbit/s (0.4 GB/s or 400 MB/s).
`Communication js full-duplex in SuperSpeed transfer mode; earlier modesare half-duplex,arbitrated by the host.“
`
`Low-power and high-power devices remain operational with this standard, but devices using SuperSpeed can take advantageof increased available current of between 150 mA and
`900 mA, respectively11
`
`, Teleased in July 2013, preserves the existing SuperSpeedtrar.sfer rate under a new label USB 3.1 Gen 1°! and introduces a sew SuperSpeed+ transfer mode, USB 3.1
`Gen 2 with the maximum datasignalingrate to 10 Gbit/s (1250 MB/s, twice the rate of USE 3.0), which reducesline encoding overheadto just 3% by changing the encoding scheme
`to 128b/1zapO78)
`
`
`USB3.2, released in September 2017, preserves existing USB 3.1 SuperSpeed and SuperSpeed+ data modesbut introduces two new SuperSpeed+ transfer mcdes over the USB-C
`connector with data rates of 10 and 20 Gbit/s (4250 and 2500 MB/s). The increase in bandwidthis a result of multilane operation over existing wires that were intendedfor flip-flop
`capabilities of the Type-C connector.)
`
`System design
`
`A USBsystem consists of a host with one or more downstream ports, and multiple peripherals, forming a tiered-startopology. Additional USB hubs maybeincluded,allowing up to
`five tiers. A USB host may have multiple controllers, cach with one or more ports. Up to 127 devices may be connected to a single host controdler.®78*Usy devices are linked in
`series through hubs. The hubbuilt into the host controller is the root hub.
`
`A USBdevice may consist of several logical sub-devices that are referred to as devicefunctions. A composite device may provide several functions, for example, a webcam (video
`
`device function)with a built-in microphone (audio device function). An alternative to this is compound
`ce, in which the host assigns each logical device a distinctive address and
`all logical devices connectto a built-in hub that connects to the physical USB cable.
`
`USB device communication is based on pipes (logiral channels). A pipe is a connection from the host controller to a logical entity, found
`on a device, and named an endpoint. Because pipes correspond to endpoints, the terms are sometimes used interchangeably. A USB
`device could have up to 32 endpoints (16 IN, 16 OUT), though it is rare to have sa many, An endpointis defined and numbered by the
`may be opened andclosed.
`
`There are two types of pipe: stream and message. A messagepipe is bi-directional and is used for contro! transfers. Message pipes are
`typically used for short, simple commandsto the device, ar-d a status response, used, for example, by the bus control pipe number 0. A
`stream pipe is a uni-directional pipe connected to a uni-directional endpointthat transfers data using an isochronous,**l interrupt, ar
`bulk transfer:
`
`logical pipes
`
` enupeints in
`the device
`
`device during initialization (the period after physical connaction called “enumeration") and so is relatively permanent, whereas a pipe
`
`
`Isochronous transfers
`At some guaranteed data rate (often, but not necessarily, as fast as possible) but with possible data loss
`(e.g., realtime audio or video)
`Interrupt transfers
`Devices that need guaranteed quick responses (bounded latency) such as pointing devices, mice, and keyboards
`Bulk transfers
`Large sporadic transfers using all remaining available bandwidth, but with no guarantees on bandwidth or latency (e.g., file transfers)
`Whena hoststarts a data transfer, it sends a TOKEN packet containing an endpoint specified with a tuple of (device_address, endpoint_number). If thetransferis from the hos| Lo
`the endpoint, the host sends an OUT packet(a specialization of a TOKEN packet) with the desired device address and endpoint number,If the data transfer is from the device to the
`host, the host sends an IN packetinstead.If the destinalion endpointis a uni-directional endpoint whose manvfacturer's designated direction does not match the TOKEN packet
`(e.g. the manufacturer's designated direction is IN while the TOKEN packet is an OUT packet), the TOKEN packetis ignored. Otherwise,it is accepted and the data transaction ean
`start. A bi-directional endpoint, on the other hand, accepts both IN and OUT packets.
`
`USB endpoints reside on the
`connected device: the channels to
`the host are referred to as pipes
`
`Endpoints are grouped into interfaces and each interface is associated with a single device function. An exception to this is endpoint zero, which is used for device configuration and
`is not associated with any interface. A single device function composed of independently controlled interfaces is called a composite device. A composite device only has 2 Single
`device address because the host only assigns a device address to a function.
`
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`USB - Wikipedia
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`When a USB device isfirst ecnnected to a USB host, the USB device enumeration process is started. The enumeration starts by sending a
`reset signal to the USB device. The data rate of the USB device is determined during the reset signaling. After reset, the USB device's
`informationis read by the host and the deviceis assigned a unique 7-bit address.if the device is supported by the host,the devicedrivers
`needed for communicating with the device are loaded and the device is set to a configured state. If the USB host is restarted, the
`enumeration process is repeated for all connected devices.
`
`The host controller directs traffic flow to devices, so no USB device can transfer any data on the bus without an explicit request from the
`hostcontroller. In USB 2.0, the host controller polls thebus for traffic, usuallyin a ro
`in fashion. The throughput of each USB port
`.
`fe
`:
`
`is determined by the slower speedofeither the LSB port or the USB device connectedto the port.
`High-speed USB 2.0 hubs contain devicesculled transaction translators that convert between high-speed USB 2.0 buses and full and low
`speed buses. There may be one lranslator per hub orper port.
`
`
`
`Two USB 3,9 standard A sockets
`tefland two USB 2.0 ae
`’
`vs front canal
`(right) Ga a computer's
`front Pane:
`
`Because there are two separate controllers in each USB 3.0 host, USB 3.0 devices transmit and receive at USB 3.0 data rates regardless of USB 2.0 or earlier devices comected to
`that hast. Operating data rates for earlier devices are set in the legacy manner.
`
`Device classesee
`The functionality of a USB device is defined by a class code sent to a USB host. This allows the host ta load software modules for the device and to support newdevices from different
`manufacturers.
`
`Device classes include:
`
`
`
`
`:
`ipClass
`Usage
`;
`Description
`}
`Examples, or exception
`
`
`:
`i Device
`|! Unspecitod
`
`interface
`
`Usea6 togetherwithclassAh(bejow) |
`
`
`
`merface
`
`
`iI i
`
`iiii
`
`
`
`x
`
`
`
`
`
`‘Interface ; CDC-Data
`"Used togetherwit class aah (above)
`Smart Card
`i usB smartcard reader=
`
`
`' Fingerprint reade!
`
`| Webcam
`
`
`Personal nealtacare device class (PHOC)
`Rulse menttoy(watch)
`
`ec {AV}
`| Webcam, Ty
`
`Device
`Billboard
`| Describes USB Ty eC altematemodes supported by oeNices
`
`. Both
`i Diagnostic|Device
`~ vee‘compliance testing device
`
`
` ; Both
`i Interface Wireless Controller
`}! Bluetooth adapter, Microsoft RNDIS
`
`
`
`i Miscellaneous
`ai ActiveSynedevice
`PFEh
`; interface Applicalion-specie
`»
`IrDA Bridge, Test & Measurement Class (USBTMC)Ha]USB DFU
`
`| FFh
`ft Both
`: Vendorepecitic
`i
`indicates that 4 device needs vendor-spectic drivers
`
`USB massstorage / USB drive
`USB mass storage deviceclass (MSC or UMS)standardizes connectionsto storage devices. Atfirst intended for magnetic and optical
`drives, it has been extended to support flash drives. It has also been extended to support a widevariety of novel devices as many systems
`can be controlled with the familiar metaphorof file manipulation within directories. The process of making a novel device look like a
`familiar device is also knownas extension. Theability to boot a write-locked SDcard with a USB adapteris particularly advantageousfor
`maintainingthe integrity and non-corruptible, pristine state of the booting medium.
`Though most personal computers since mid-2004 can boot from USB mass storage devices, USB is not intended as a primary bus fora
`computer's internal storage.
`. However, USB has the advantage of allowing hot-swapping, making it useful for mobile peripherals,
`including drives of various kinds.
`First conceived and still used today far optical storage devices (CD-RW drives, DVDdrives, ctc.), several manufacturers offer external
`portable USB hard disk drives, or emptyenclosuresfor disk drives. These offer performance comparable to internal drives, limited by the current number and types of attached USB
`devices, and by the upper limit of the USB interface. Other competing standards for external drive connectivity include eSATA, ExpressCard, FireWire (IEEE 1394), and most
`recentlyThunderbolt.
`
`A ‘lash drive, a tycical USB mass-
`storage devica
`
`¥ *.
`
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`Another use for USB mass storage devices is the portable execution of software applications (such as web browsers and VoIPclients) with
`no need to install them on the host computer.“
`
`Windows Phone 8 (Windows Phone 7 devices had used the Zune protocol—an evolution of MTP). The primary reason for this is that MTP :
`
`Media Transfer Protocol
`
`Media TransferProtocol (MTP) was designed by Microsoft to give higher-level access to a device's filesystem than USB massstorage, at
`the level of files rather than disk blocks. It also has optional DRM features. MTP was designed for use with portable mediaplayers, butit
`has since been adopted as the primary storage access protocol of the An
`
`peratingsystem from the version 4.1 Jelly Bean as well as
`a
`.
`.
`.
`.
`does not require exclusive access to the storage device the way UMS does,alleviating potential problems should an Android program
`request the storage while it is attached to a computer. The main drawbackis that MTPis not as well supported outside of Windows
`operating systems.
`
`Circuit board from a USB 3.0
`extemal 2.5-inch SATA HDD
`enclosure
`
`Human Interface devices
`
`Joysticks, keypads, tablets and other human-interface devices (HIDs) are also progressively migrating from MIDI, and PC gameport connectors to USB.
`
`USB mice and keyboards can usually be used with older computers that have PS/2connectors with the aid of a small USB-to-PS/2 adapter. For mice and keyboards with dual-
`protocol support, an adaptorthat containsno logic circuitry may be used: the hardware in the USB keyboard or mouseis designed to detect whetherit is connected to a USB or PS/2
`port, and communicate using the appropriate protocol. Convertersalso exist that connect PS/2 keyboards and mice (usually one of each) to a USB port.'*! These devices present two
`
`HID endpoints to the system and use a mic
`troller to perfarm bidirectional data translation between the twostandards.
`
`Device Firmware Upgrade
`Device Firmware Upgrade (DFU) is a vendor- and device-independent mechanism for upgrading the firmware of USB devices with improved versions provided by their
`manufacturers, offering (for example) a way to deploy firmware bug fixes. During the firmware upgrade operation, USB devices changetheir operating mode effectively becoming a
`PROM programmer. Anyclass ofUSB device can implementthis capability by followingtheofficial DFU specifications."
`
`In addition to its intended legitimate purposes, DFU ean also be exploited by uploading maliciously crafted firmware that causes USB devices to spoof variousother device types; one
`such exploiting approach is known as BadusB.!")
`
`Connectors
`Thethree sizes of USB connectors are the default or standard format intended for desktop or portable equipment, the mini intended for mobile equipment , and the thinner micro
`size, for low-profile mobile equipment such as mobile phones andtablets. There are five speeds for USB data transfer: Law Speed, Full Speed, High Speed (from version 2.0 of the
`specification), SuperSpeed(from version 3.0), and SuperSpeed+ (from version 3.1). The modes have differing hardware and cabling requirements. USB devices have some choice of
`implemented modes, and USB version‘s nota reliable statement of implemented modes. Modesare identified by their names and icons, and the specifications suggests thal plugs
`and receptacles be colour-coded (SuperSpeedis identified by blue).
`
`Unlike other data buses (such as Ethernet), USB connections are directed; a host device has "downstream" facing ports that connect to the "upstream"ports of devices. Only
`downstream facing ports provide power; this topology was chosen to easily prevent electrical overloads and damaged equipment. Thus, USB cables have different ends: A and B,
`with different physical connectors for each. Each formathas a plug and receptacle defined for each of the A and B ends. USBcables have plugs, and the corresponding receptacles are
`on the computers or electronic devices. In commonpractice, the A endis usually the standard format, and the B side varies over standard, mini, and micro. The mini and micro
`formats also provide for USBOn-The-Go with a hermaphroditic AB receptacle, which accepts either an A or a B plug. On-The-Go allows USB between peers without discarding the
`directed topology by choosing the host at connection time;it also allows one receptacle to perform double duty in space-consirained applicalions.
`
`Connector properties
`The connectors the USB committee specifies support a number of USB’'s underlying goals, and reflect lessons learned from the many
`connectors the computer industry has used. The female connector mounted onthe host ordeviceis called the receptacle, and the male
`(50) p51]
`canneclor allached to Lhe cable is called the plug,’
`
`By design, it is difficult to insert a USB plug into its reccptaclc incorrectly. The USB specification requires that the cable plug and
`receptacle be marked so the user can recognize the proper orientation. ©! The type-C plug is reversible. USB cables and small USB
`devices are held in place by the gripping force from the receptacle, with no screws,clips, or thumb-turnsas other connectors use.
`
`
`
`aE
`ee
`
`The different A and B plugs prevent accidentally connecting two power sources. However, some of this directed topology is lost with the
`advent of multi-purpose USB connections (such as USBOn-The-Go in smartphones, and USB-powered Wi-Fi routers), which require
`A-ta-A, B-to-B, and sometimes Y/splitter cables. See the USB On-The-Go connectors section below for a more detailed summary
`description. There are cables with A plugs on both ends, which maybevalidif the cable includes, for example, a USB host-to-hosttransfer
`device with 2 parts.
`
`Durability
`The standard connectors were designed to be mare robust than many past connectors. This is because USB is hot-pluggable, and the connectors
`would be used more frequently, and perhaps with less care, than previous connectors.
`
`Standard USB has a minimum ratedlifetimeof 1,500 eycles of insertion and removal,™! the mini-USB receptacle increasesthis to 5,000 cycles,
`and the newer Micro-USB®! and USB-C receptacles are both designed for a minimumratedlifetime of 10,000 cyclesof insertion and removal.©4
`To accomplish this, a locking device was added andthe leaf-spring was moved from thejack to the plug, so that the most-stressed part is on the
`cable side of the cannection. This change was madeso that the connector on the less expensive cable would bear the mostwear.°"!54)
`
`Type-A plug and, as part of 5 non-
`Standard cable, receptacle
`
`
`
`USB extension cable
`
`https://en.wikipedia.org/wiki/USB
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`In standard USB,the electrical contacts in a USB connector are protected hy an adjacentplastic tongue, and theentire connecting assembly is usually protected by an enclosing
`metal shel
`7(531
`
`The shell on the plug makes contact with the receptacle before any of the internal pins. Theshellis typica‘ly grounded,to dissipate static electricity and to shield the wires within the
`connector,
`
`The micro format has the highest designed insertion lifetime. The standard and mini connectors have a design lifetime of 1,500 insertion-removalcycles,®9 the improved Mini-B
`connectorsincreased this to 5,000. The micro connectors were designed with frequent charging of portable devices in mind, so have a design life of 10,000 cycles!**l and also place
`the flexible contacts, which wear out sooner, on the easily replaced cable, while the more durable rigid contacts are located in the receptacles. Likewise, the springy componentof the
`retention mechanism,parts that provide required gripping force, were also moved into plugs on the cable side.®5)
`
`Campatibility
`USBspecific
`The USB standard specifies tolerances for compliant USB eennectors to minim‘ze physical incompatibilities in connectors trom
`
`
`ons or supp
`
`cent ports are not block:
`1, Compliant devices m
`the size restr
`
`
`also detines
`
`
`operate in different modes depending on whether the data connection is made. Charging docks supply
`
`Connector types
`USB connector types multiplied as the specification progressed. The original USB specification detailed
`standard-A and standard-B plugs and receptacles.The connectors were different so that users could not
`connect one computerreceptacle to another. The data pins in the standard plugs are recessed compared to
`the power pins,so that the device can power up before establishing a data connection. Some devices
`
`power and do notinclude a host device or data pins, allowing any capable USB device to charge or operate
`from a standard USB cable. Charging cables provide power connections, but not data. In a charge-only
`cable, the data wires are shorted at the device end, otherwise the device may reject the charger as
`unsuitable.
`
`mY
`
`sey geteateg eget
`7
`fit
`evel
`everaare
`Various USS cannecters along a centimeter ruler for scale, From
`laft to rignt: Micro-2