|
|
Menu
Navigation
Software
Hardware
Facts & Information
Categories
Toolbox
|
(Difference between revisions)
Big (Talk | contribs) (New page: {{Redirect|USB}} {{Infobox Computer Hardware Bus | name = USB | fullname = Universal Serial Bus | image = Certified USB.svg | caption = Original USB Logo | invent-d...) Newer edit → Current revisionTemplate:Redirect Template:Infobox Computer Hardware Bus Image:USB TypeA Plug.JPG Image:USB Icon.svg In information technology, Universal Serial Bus (USB) is a serial bus standard to interface devices to a host computer. USB was designed to allow many peripherals to be connected using a single standardized interface socket and to improve the Plug and play capabilities by allowing hot swapping, that is, by allowing devices to be connected and disconnected without rebooting the computer or turning off the device. Other convenient features include providing power to low-consumption devices without the need for an external power supply and allowing many devices to be used without requiring manufacturer specific, individual device drivers to be installed. USB is intended to replace many legacy varieties of serial and parallel ports. USB can connect computer peripherals such as mice, keyboards, PDAs, gamepads and joysticks, scanners, digital cameras, printers, personal media players, flash drives, and external hard drives. For many of those devices USB has become the standard connection method. USB was originally designed for personal computers, but it has become commonplace on other devices such as PDAs and video game consoles, and as a bridging power cord between a device and an AC adapter plugged into a wall plug for charging purposes. Template:As of, there are about 2 billion USB devices sold per year, and about 6 billion total sold to date.[1] The design of USB is standardized by the USB Implementers Forum (USB-IF), an industry standards body incorporating leading companies from the computer and electronics industries. Notable members have included Agere (now merged with LSI Corporation), Apple Inc., Hewlett-Packard, Intel, NEC, and Microsoft. HistoryThe USB 1.0 specification model was introduced in 1996. USB was created by the core group of companies that consisted of Intel, Compaq, Microsoft, Digital, IBM, and Northern Telecom. Intel produced the UHCI host controller and open software stack; Microsoft produced a USB software stack for Windows and co-authored the OHCI host controller specification with National Semiconductor and Compaq; Philips produced early USB-Audio; and TI produced the most widely used hub chips. Originally USB was intended to replace the multitude of connectors at the back of PCs, as well as to simplify software configuration of communication devices. The original Apple "Bondi blue" iMac G3, introduced May 6, 1998, was the first computer to offer USB ports without offering "legacy" ports.[2] [3] USB 1.1 came out in September 1998 to help rectify the adoption problems that occurred with earlier iterations of USB, mostly those relating to hubs.[4] The USB 2.0 specification was released in April 2000 and was standardized by the USB-IF at the end of 2001. Hewlett-Packard, Intel, Lucent (now LSI Corporation since its merger with Lucent spinoff Agere Systems), Microsoft, NEC, and Philips jointly led the initiative to develop a higher data transfer rate, 480 Mbits/s, than the 1.1 specification of 12 Mbits/s. The USB 3.0 specification was released on November 17, 2008 by the USB 3.0 Promoter Group. It has a transfer rate of up to 10 times faster than the USB 2.0 version and has been dubbed the SuperSpeed USB. Equipment conforming with any version of the standard will also work with devices designed to any previous specification (known as backward compatibility). OverviewA USB system has an asymmetric design, consisting of a host, a multitude of downstream USB ports, and multiple peripheral devices connected in a tiered-star topology. Additional USB hubs may be included in the tiers, allowing branching into a tree structure with up to five tier levels. A USB host may have multiple host controllers and each host controller may provide one or more USB ports. Up to 127 devices, including the hub devices, may be connected to a single host controller. USB devices are linked in series through hubs. There always exists one hub known as the root hub, which is built into the host controller. So-called "sharing hubs", which allow multiple computers to access the same peripheral device(s), also exist and work by switching access between PCs, either automatically or manually. They are popular in small-office environments. In network terms, they converge rather than diverge branches. A physical USB device may consist of several logical sub-devices that are referred to as device functions. A single device may provide several functions, for example, a webcam (video device function) with a built-in microphone (audio device function). Image:USB pipes and endpoints (en).svg USB device communication is based on pipes (logical channels). Pipes are connections from the host controller to a logical entity on the device named an endpoint. The term endpoint is occasionally used to incorrectly refer to the pipe. A USB device can have up to 32 active pipes, 16 into the host controller and 16 out of the controller. Each endpoint can transfer data in one direction only, either into or out of the device, so each pipe is uni-directional. 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 which is not associated with any interface. When a USB device is first connected to a USB host, the USB device enumeration process is started. The enumeration starts by sending a reset signal to the USB device. The speed of the USB device is determined during the reset signaling. After reset, the USB device's information is read by the host, then the device is assigned a unique 7-bit address. If the device is supported by the host, the device drivers 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 host controller. In USB 2.0, host controller polls the bus for traffic, usually in a round-robin fashion. In SuperSpeed USB, connected device can request service from host. Device classesUSB defines class codes used to identify a device’s functionality and to load a device driver based on that functionality. This enables a device driver writer to support devices from different manufacturers that comply with a given class code. Device classes include:[5]
Template:Fnb Use class information in the Interface Descriptors. This base class is defined to be used in Device Descriptors to indicate that class information should be determined from the Interface Descriptors in the device. USB mass-storageHere is the complete setlist for Guitar Hero III, which will also include all downloadable content (when released).
Single Player Setlist1. Starting Out Small
2. Your First Real Gig
3. Making The Video
4. European Invasion
5. Bighouse Blues
6. The Hottest Band On Earth
7. Live in Japan
8. Battle For Your Soul
Co-Op Setlist1. Getting a Band Together
2. We Just Wanna Be Famous
3. Overnight Success
4. Getting the Band Back Together
5. Jailhouse Rock
6. Battle for Your Souls...
Bonus Tracks
Downloadable ContentSinglesHalo Theme MJOLNIR Mix - Released November 22, 2007 on XBL. Ernten Was Wir Säen - Released December 20, 2007 on XBL & January 3, 2008 on PSN. So Payso - Released December 20, 2007 on XBL & January 3, 2008 on PSN.
Antisocial - Released December 20, 2007 on XBL and January 3, 2008 on PSN.
We Three Kings - Released December 20, 2007 on XBL & PSN. Dream On - Released Febuary 18, 2008 on XBL & PSN. I am Murloc - Released June 26, 2008 on XBL and PSN.
Track PacksCompanion Pack - Released October 31, 2007 on XBL. Foo Fighters Pack - Released November 8, 2007 on XBL & PSN. Velvet Revolver Pack - Released November 8, 2007 on XBL & PSN. Boss Battle Pack - Released November 15, 2007 on XBL and November 29, 2007 on PSN. Warner/Reprise Track Pack - Released December 20, 2007 on XBL and January 3, 2007 on PSN. Classic Rock Track Pack - Released January 24, 2008 on XBL and PSN.
No Doubt Track Pack - Released Febuary 28, 2008 on XBL and PSN. Modern Metal Track Pack - Released March 6, 2008 on XBL & PSN. Dropkick Murphys Track Pack - Released March 13, 2008 on XBL & PSN. Def Leppard Track Pack - Released April 24, 2008 on XBL & PSN.
Guitar Virtuoso Pack - Released July 24, 2008 on XBL & PSN. DragonForce Track Pack - Released August 21, 2008 on XBL & PSN USB implements connections to storage devices using a set of standards called the USB mass storage device class (referred to as MSC or UMS). This was initially intended for traditional magnetic and optical drives, but has been extended to support a wide variety of devices, particularly flash drives. This generality is because many systems can be controlled with the familiar idiom of file manipulation within directories (The process of making a novel device look like a familiar device is also known as extension). Though most newer computers are capable of booting off USB Mass Storage devices, USB is not intended to be a primary bus for a computer's internal storage: buses such as ATA (IDE), Serial ATA (SATA), and SCSI fulfill that role. However, USB has one important advantage in that it is possible to install and remove devices without opening the computer case, making it useful for external drives. Originally conceived and still used today for optical storage devices (CD-RW drives, DVD drives, etc.), a number of manufacturers offer external portable USB hard drives, or empty enclosures for drives, that offer performance comparable to internal drivesTemplate:Fact. These external drives usually contain a translating device that interfaces a drive of conventional technology (IDE, ATA, SATA, ATAPI, or even SCSI) to a USB port. Functionally, the drive appears to the user just like an internal drive. Other competing standards that allow for external connectivity are eSATA and FireWire. Another use for USB Mass Storage devices is the portable running of software applications without the need of installation on the host computer[6], eg. Web Browser, VoIP[7], etc. Human-interface devices (HIDs)Mice and keyboards are frequently fitted with USB connectors, but because most PC motherboards still retain PS/2 connectors for the keyboard and mouse as of 2007, they are often supplied with a small USB-to-PS/2 adaptor, allowing usage with either USB or PS/2 interface. There is no logic inside these adaptors: they make use of the fact that such HID interfaces are equipped with controllers that are capable of serving both the USB and the PS/2 protocol, and automatically detect which type of port they are plugged into. Joysticks, keypads, tablets and other human-interface devices are also progressively migrating from MIDI, PC game port, and PS/2 connectors to USB. Apple Macintosh computers have been using USB exclusively for all external wired mice and keyboards since January 1999. The original iMac raised public awareness of USB considerably in August 1998, as it discarded legacy ports to use only USB. PCs had USB ports prior to the iMac's introduction, but they were included with a full complement of traditional ports which slowed down USB's adoption. The iMac's influence can be seen in the number of USB peripherals with matching translucent, colored plastic enclosures that were available in the late '90s and early '00s. USB signalingUSB supports following data rates:
Experimental data rate:
USB signals are transmitted on a twisted pair data cable with 90Ω ±15% impedance,[8] labeled D+ and D−. These collectively use half-duplex differential signaling to combat the effects of electromagnetic noise on longer lines. Transmitted signal levels are 0.0–0.3 volts for low and 2.8–3.6 volts for high in Full Speed (FS) and Low Speed (LS) modes, and -10–10 mV for low and 360–440 mV for high in High Speed (HS) mode. In FS mode the cable wires are not terminated, but the HS mode has termination of 45Ω to ground, or 90Ω differential to match the data cable impedance. A USB connection is always between a host or hub at the "A" connector end, and a device or hub's upstream port at the other end. The host includes 15 kΩ pull-down resistors on each data line. When no device is connected, this pulls both data lines low into the so-called "single-ended zero" state (SE0 in the USB documentation), and indicates a reset or disconnected connection. A USB device pulls one of the data lines high with a 1.5 kΩ resistor. This overpowers one of the pull-down resistors in the host and leaves the data lines in an idle state called "J". The choice of data line indicates a device's speed support; full-speed devices pull D+ high, while low-speed devices pull D− high. USB data is transmitted by toggling the data lines between the J state and the opposite K state. USB encodes data using the NRZI convention; a 0 bit is transmitted by toggling the data lines from J to K or vice-versa, while a 1 bit is transmitted by leaving the data lines as-is. To ensure a minimum density of signal transitions, USB uses bit stuffing; an extra 0 bit is inserted into the data stream after any appearance of six consecutive 1 bits. Seven consecutive 1 bits is always an error. A USB frame begins with an 8-bit synchronization sequence 00000001. That is, after the initial idle state J, the data lines toggle KJKJKJKK. The final 1 bit (repeated K state) marks the end of the sync pattern and the beginning of the USB frame proper. A USB frame's end, called EOP (end-of-packet), is indicated by the transmitter driving 2 bit times of SE0 (D+ and D- both below Vil max) and 1 bit time of J state. After this, the transmitter ceases to drive the D+/D− lines and the aforementioned resistors hold it in the J (idle) state. A receiver may take extra time to decode the SE0 state, and will see the first bit time as a repetition of the last data bit. Since USB frames are always a multiple of 8 bits long, this extra "dribble bit" can be detected and ignored. A USB bus is reset using a prolonged (10 to 20 milliseconds) SE0 signal. USB 2.0 devices use a special protocol during reset, called "chirping", to negotiate the High-Speed mode with the host/hub. A device that is HS capable first connects as an FS device (D+ pulled high), but upon receiving a USB RESET (both D+ and D- driven LOW by host for 10 to 20 mS) it pulls the D- line high. If the host/hub is also HS capable, it chirps (returns alternating J and K states on D- and D+ lines) letting the device know that the hub will operate at High Speed. Clock tolerance is 480.00 Mbit/s ±500 ppm, 12.000 Mbit/s ±2500 ppm, 1.50 Mbit/s ±15000 ppm. Though Hi-Speed devices are commonly referred to as "USB 2.0" and advertised as "up to 480 Mbit/s", not all USB 2.0 devices are Hi-Speed. The USB-IF certifies devices and provides licenses to use special marketing logos for either "Basic-Speed" (low and full) or Hi-Speed after passing a compliance test and paying a licensing fee. All devices are tested according to the latest spec, so recently-compliant Low-Speed devices are also 2.0 devices. The actual throughput Template:As of attained with real devices is about two thirds of the maximum theoretical bulk data transfer rate of 53.248 MB/s. Typical hi-speed USB devices operate at lower speeds, often about 3 MB/s overall, sometimes up to 10–20 MB/s.[9] USB packetsUSB communication takes the form of packets. Initially, all packets are sent from the host, via the root hub and possibly more hubs, to devices. Some of those packets direct a device to send some packets in reply. After the sync field described above, all packets are made of 8-bit bytes, transmitted least-significant bit first. The first byte is a packet identifier (PID) byte. The PID is actually 4 bits; the byte consists of the 4-bit PID followed by its bitwise complement. This redundancy helps detect errors. (Note also that a PID byte contains at most four consecutive 1 bits, and thus will never need bit-stuffing, even when combined with the final 1 bit in the sync byte. However, the OUT PID byte ends with three consecutive 1 bits, so if the following USB device address begins with three 1 bits, bit-stuffing will be required.) Packets come in three basic types, each with a different format and CRC (cyclic redundancy check): Handshake packetsHandshake packets consist of nothing but a PID byte, and are generally sent in response to data packets. The three basic types are ACK, indicating that data was successfully received, NAK, indicating that the data cannot be received at this time and should be retried, and STALL, indicating that the device has an error and will never be able to successfully transfer data until some corrective action (such as device initialization) is performed. USB 2.0 added two additional handshake packets, NYET which indicates that a split transaction is not yet complete, and an ERR handshake to indicate that a split transaction failed. The only handshake packet the USB host may generate is ACK; if it is not ready to receive data, it should not instruct a device to send any. Token packetsToken packets consist of a PID byte followed by 11 bits of address and a 5-bit CRC. Tokens are only sent by the host, never a device.-- IN and OUT tokens contain a 7-bit device number and 4-bit function number (for multifunction devices) and command the device to transmit DATAx packets, or receive the following DATAx packets, respectively. An IN token expects a response from a device. The response may be a NAK or STALL response, or a DATAx frame. In the latter case, the host issues an ACK handshake if appropriate. An OUT token is followed immediately by a DATAx frame. The device responds with ACK, NAK, or STALL, as appropriate. SETUP operates much like an OUT token, but is used for initial device setup. Every millisecond (12000 full-speed bit times), the USB host transmits a special SOF (start of frame) token, containing an 11-bit incrementing frame number in place of a device address. This is used to synchronize isochronous data flows. High-speed USB 2.0 devices receive 7 additional duplicate SOF tokens per frame, each introducing a 125 µs "microframe". USB 2.0 added a PING token, which asks a device if it is ready to receive an OUT/DATA packet pair. The device responds with ACK, NAK, or STALL, as appropriate. This avoids the need to send the DATA packet if the device knows that it will just respond with NAK. USB 2.0 also added a larger SPLIT token with a 7-bit hub number, 12 bits of control flags, and a 5-bit CRC. This is used to perform split transactions. Rather than tie up the high-speed USB bus sending data to a slower USB device, the nearest high-speed capable hub receives a SPLIT token followed by one or two USB packets at high speed, performs the data transfer at full or low speed, and provides the response at high speed when prompted by a second SPLIT token. The details are complex; see the USB specification. Data packetsThere are two basic data packets, DATA0 and DATA1. Both consist of a DATAx PID field, 0–1023 bytes of data payload (up to 1024 in high speed, at most 8 at low speed), and a 16-bit CRC. They must always be preceded by an address token, and are usually followed by a handshake token from the receiver back to the transmitter. The two packet types provide the 1-bit sequence number required by Stop-and-wait ARQ. If a USB host does not receive a response (such as an ACK) for data it has transmitted, it does not know if the data was received or not; the data might have been lost in transit, or it might have been received but the handshake response was lost. To solve this problem, the device keeps track of the type of DATAx packet it last accepted. If it receives another DATAx packet of the same type, it is acknowledged but ignored as a duplicate. Only a DATAx packet of the opposite type is actually received. When a device is reset with a SETUP packet, it expects a DATA0 packet next. USB 2.0 added DATA2 and MDATA packet types as well. They are used only by high-speed devices doing high-bandwidth isochronous transfers which need to transfer more than 1024 bytes per 125 µs "microframe" (8192 kB/s). PRE "packet"Low-speed devices are supported with a special PID value, PRE. This marks the beginning of a low-speed packet, and is used by hubs which normally do not send full-speed packets to low-speed devices. Since all PID bytes include four 0 bits, they leave the bus in the full-speed K state, which is the same as the low-speed J state. It is followed by a brief pause during which hubs enable their low-speed outputs, already idling in the J state, then a low-speed packet follows, beginning with a sync sequence and PID byte, and ending with a brief period of SE0. Full-speed devices other than hubs can simply ignore the PRE packet and its low-speed contents, until the final SE0 indicates that a new packet follows. USB protocol analyzersDue to the complexities of the USB protocol, USB protocol analyzers are invaluable tools to USB device developers. USB analyzers are able to capture the data on USB and display information from low-level bus states to high-level data packets and class-level information. USB connector propertiesImage:Male and Female USB Connectors.jpg The connectors specified by the USB committee were designed to support a number of USB's underlying goals, and to reflect lessons learned from the varied menagerie of connectors then in service. Usability
Durability
Compatibility
Interface
Cables
(NS: non-standard, existing for specific proprietary purposes not at the guidance of the USB-IF.) In addition to these cable assemblies also a cable with Micro-A and Standard-A receptacle is compliant with USB specifications. Other combinations of connectors are not compliant. However, some older devices and cables with Mini-A connector have been certified by USB-IF; the Mini-A connector has been deprecated, and no new certification for assemblies using Mini-A connector will be allowed.[10] Types of USB connectorImage:Types-usb new.svg Image:USB types 2.jpg Image:USB.svg There are several types of USB connectors, including some that have been added while the specification progressed. The original USB specification detailed Standard-A and Standard-B plugs and receptacles. The first engineering change notice to the USB 2.0 specification added Mini-B plugs and receptacles. The data connectors in the A - Plug are actually recessed in the plug as compared to the outside power connectors. This permits the power to connect first which prevents data errors by allowing the device to power up first and then transfer the data. Some devices will operate in different modes depending on whether the data connection is made. This difference in connection can be exploited by inserting the connector only partially. For example, some battery-powered MP3 players switch into file transfer mode (and cannot play MP3 files) while a USB plug is fully inserted, but can be operated in MP3 playback mode using USB power by inserting the plug only part way so that the power slots make contact while the data slots do not. This enables those devices to be operated in MP3 playback mode while getting power from the cable. USB-AThe Standard-A type of USB connectors takes on the appearance of flattened rectangles that plugs into downstream-port sockets on the USB host or a hub. This kind of connector is most frequently seen on cables that are permanently attached to a device, such as one on a cable that connects a keyboard or mouse to the computer. USB-BStandard-B connectors—which have a square shape with beveled exterior corners—typically plug into upstream sockets on devices that use a removable cable, e.g. between a hub and a printer. This two-connector scheme prevents a user from accidentally creating a loop. [11] Mini, MicroTemplate:Cleanup-section Various non-standard connectors; the now-deprecated [12] (but standardized) Mini-A and the current standard Mini-B, Micro-A, and Micro-B connectors ... all of these are used for smaller devices such as PDAs, mobile phones or digital cameras. The Standard-A plug is approximately 4 by 12 mm, the Standard-B approximately 7 by 8 mm, and the Mini-A and Mini-B plugs approximately 2 by 7 mm. Image:Micro-USB.jpg Image:Micro-USB-jacks.jpg The Micro-USB connector was announced by the USB-IF on January 4, 2007 and the Mini-USB connectors were withdrawn.[13] In late 2008, most small USB connectors and cables in use are still the Mini style, but some devices use the new Micro connectors. The Micro-USB connections are intended to replace the Mini-USB plugs used in new devices including smartphones and Personal digital assistants. This Micro-USB plug is rated for 10,000 connect-disconnect cycles. It is about half the height of the mini-USB connector, but features a similar width. In the Universal Serial Bus Micro-USB Cables and Connectors Specification, details have been laid down for Micro-A plugs, Micro-AB receptacles, and Micro-B plugs and receptacles, along with a Standard-A receptacle to Micro-A plug adapter. The carrier led group OMTP have recently endorsed micro-USB as the standard connector for data and power on mobile devices.[14] These include various types of battery chargers, allowing Micro-USB to be the single external cable link needed by some devices. USB OTG Sockets: Mini-AB, Micro-ABExcept for special standard-to-Mini-A and standard-to-Micro-A adapters, USB cables always have an A-connector and a B-connector, on opposite ends. A-connectors can always connect to A-sockets; B-connectors can always connect B-sockets. These sockets all come in standard, mini, and micro versions. For USB On-The-Go (or 'OTG') support another socket type is defined: the AB, in both mini and micro versions. It can accept both A and B connector, through careful mechanical design. OTG software detects the difference by use of the ID pin, which is grounded in A-connectors and is otherwise floating. When an A-connector is connected to an AB socket, the socket supplies VBUS power to the cable and starts in the host role. When a B-connector is used, the socket consumes VBUS power and starts in the peripheral or device role. OTG allows those two roles to be switched by software, as needed for the task at hand. Proprietary connectors and formatsMicrosoft's original Xbox game console uses standard USB 1.1 signaling in its controllers and memory cards, but features proprietary connectors and ports. Similarly, IBM UltraPort uses standard USB signaling, but via a proprietary connection format. American Power Conversion uses USB signaling and HID device class on its uninterruptible power supplies using 10P10C connectors. HTC manufactures Windows Mobile-based Communicators and the T-Mobile G1 which have a proprietary connector called HTC ExtUSB. The ExtUSB combines mini-USB (with which it is backwards-compatible) with audio input and output. Nokia includes a USB connection as part of the Pop-Port connector on their mobile phones. The second-generation iPod Shuffle uses a TRS connector to carry USB, audio, or power signals. Many digital cameras have a tiny 8 pin connector that combines USB with video and audio out. There are at least 10 different types of non-standard Mini-USB receptacles and jacks currently in use. Because of this, the USB-IF created the Micro series of receptacles and jacks, so as to standardize on one jack that delivers both power and data. USB cables
The maximum length of a standard USB cable is Template:Convert. The primary reason for this limit is the maximum allowed round-trip delay of about 1500 ns. If a USB device does not answer to host commands within the allowed time, the host considers the command to be lost. When adding up the USB device response time, delays from using the maximum number of hubs, and delays from the connecting cables, the maximum acceptable delay per cable turns out to be 26 ns.[15] The USB 2.0 specification requires cable delay to be less than 5.2 ns per meter (which is close to the maximum achievable speed for standard copper cable).[16] This allows for a 5 meter cable.
The data cables are a Twisted pair to reduce noise and crosstalk. Maximum useful distanceUSB1.1 maximum cable length is 3m[17]. USB2.0 maximum cable length is 5m. Maximum hubs connected in series is 5. Maximum devices connected in total is 127. Although a single cable is limited to 5 meters, the USB2.0 specification permits up to five USB hubs in a long chain of cables and hubs. This allows for a maximum distance of 30 meters between host and device, using six 5-meter cables and five hubs. In actual use, since some USB devices have built-in cables for connecting to the hub, the maximum achievable distance is 25 meters + the length of the device's cable. USB 3.0 does not define cable assembly lengths, except that it can be of any length as long as it meets all the requirements defined in the specification. However, electronicdesign.com estimated cables will be limited to 3 m at top speed.[18] Since USB provides power for devices connected to the bus, a special type of USB extender cable was created, consisting of a miniature one-port USB hub molded onto one end of a 5-meter cable. These mini-hubs are fully self-contained within the cable, requiring no separate bulky hub device and no external power. They are as simple to use as plugging cables together, with each hub drawing power through all the previous single-port hubs in the chain. Because bus power is limited, the most practical arrangement consists of four single-port hub extender cables, one plain 5 meter cable and, at the very end, a powered multiport hub to support multiple USB devices. PowerThe USB specification provides a 5 V supply on a single wire from which connected USB devices may draw power. The specification provides for no more than 5.25 V and no less than 4.75 V (5 V±5%) between the positive and negative bus power lines.[19] A unit load is defined as 100mA in USB 2.0, and was raised to 150mA in USB 3.0. A maximum of 5 unit loads can be drawn from a port in USB 2.0, and was raised to 6 in USB 3.0. There are two types of devices: low-power and high-power. Low-power devices draw at most 1 unit load, with minimum operating voltage of 4.4V in USB 2.0, and 4V in USB 3.0. High-power devices draw the maximum number of unit loads supported by the standard. All devices default as low-power but the device's software may request high-power as long as the power is available on the providing bus.[20] A bus-powered hub is initialized at 1 unit load and transitions to maximum unit loads after hub configuration is obtained. Any device connected to the hub will draw 1 unit load regardless of the current draw of devices connected to other ports of the hub (i.e 1 device connected on a 4 port hub will only draw 1 unit load despite the fact that all unit loads are being supplied to the hub).[20] A self-powered hub will supply maximum supported unit loads to any device connected to it. A battery powered hub may supply maximum unit loads to port. In addition, the VBUS will supply 1 unit load upstream for communication if parts of the Hub are powered down. [20] In Battery Charging Specification, new powering modes are added to the USB specification. A host or hub charger can supply maximum 1.5A when communicating at low-speed or full-speed, maximum 900mA when communicating at hi-speed, no upper current limit when no communication is taking place. Dedicated charger can supply maximum 1.5A of current. A portable device can draw up to 1.8A from a dedicated charger. The dedicated charger shorts the D+ and D- pins together and will not send or receive any information on those lines, allowing for the creation of very simple, high current chargers to be manufactured. The increased current (faster charging) will occur once the host/hub and devices both support the new charging specification. As of June 14, 2007, all new mobile phones applying for a license in China are required to use the USB port as a power port.[21][22] In September, 2007 the Open Mobile Terminal Platform—a forum dominated by mobile network operators but including manufacturers such as Nokia, Samsung, Motorola, Sony Ericsson and LG—announced that its members had agreed on micro-USB as the future common connector for mobile devices.[23][24] Non-standard devicesA number of USB devices require more power than is permitted by the specifications for a single port. This is a common requirement of external hard and optical disc drives and other devices with motors or lamps. Such devices can be used with an external power supply of adequate rating, which is allowed by the standard, or by means of a dual input USB cable, one input of which is used for power and data transfer, the other solely for power, which makes the device a non-standard USB device. Some external hubs may, in practice, supply more power to USB devices than required by the specification but a standard compliant device must not depend on this. Some non-standard USB devices use the 5 V power supply without participating in a proper USB network. These are usually referred to as USB decorations. The typical example is a USB-powered reading light; fans, mug heaters (though some may include USB hubs[25]), battery chargers (particularly for mobile telephones), miniature vacuum cleaners, a miniature Lava Lamp, and even toy missile launchers are available. In most cases, these items contain no digitally based circuitry, and thus are not proper USB devices at all. This can theoretically cause problems with some computers — the USB specification requires that devices connect in a low-power mode (100 mA maximum) and state how much current they need, before switching, with the host's permission, into high-power mode. In addition to limiting the total average power used by the device, the USB specification limits the inrush current (to charge decoupling and bulk capacitors) when the device is first connected; otherwise, connecting a device could cause glitches in the host's internal power. Also, USB devices are required to automatically enter ultra low-power suspend mode when the USB host is suspended; many USB hosts do not cut off the power supply to USB devices when they are suspended since resuming from the suspended state would become a lot more complicated if they did. There are also devices at the host end that do not support negotiation, such as battery packs that can power USB powered devices; some provide power, while others pass through the data lines to a host PC. USB Power adapters convert utility power and/or power from a car's electrical system to run attached devices. Some of these devices can supply up to 1 A of current. Without negotiation, the powered USB device is unable to inquire if it is allowed to draw 100 mA, 500 mA, or 1 A. The Apple SuperDrive uses a non-standard IDE-USB controller to negotiate with the MacBook Air to draw 1.5 A from the USB port.Template:Fact Even with hub supporting the necessary current, SuperDrive may not work with generic hubs.Template:Fact A workaround is to use a replacement IDE to USB bridge.[26] Powered USBHere is the complete setlist for Guitar Hero III, which will also include all downloadable content (when released).
Single Player Setlist1. Starting Out Small
2. Your First Real Gig
3. Making The Video
4. European Invasion
5. Bighouse Blues
6. The Hottest Band On Earth
7. Live in Japan
8. Battle For Your Soul
Co-Op Setlist1. Getting a Band Together
2. We Just Wanna Be Famous
3. Overnight Success
4. Getting the Band Back Together
5. Jailhouse Rock
6. Battle for Your Souls...
Bonus Tracks
Downloadable ContentSinglesHalo Theme MJOLNIR Mix - Released November 22, 2007 on XBL. Ernten Was Wir Säen - Released December 20, 2007 on XBL & January 3, 2008 on PSN. So Payso - Released December 20, 2007 on XBL & January 3, 2008 on PSN.
Antisocial - Released December 20, 2007 on XBL and January 3, 2008 on PSN.
We Three Kings - Released December 20, 2007 on XBL & PSN. Dream On - Released Febuary 18, 2008 on XBL & PSN. I am Murloc - Released June 26, 2008 on XBL and PSN.
Track PacksCompanion Pack - Released October 31, 2007 on XBL. Foo Fighters Pack - Released November 8, 2007 on XBL & PSN. Velvet Revolver Pack - Released November 8, 2007 on XBL & PSN. Boss Battle Pack - Released November 15, 2007 on XBL and November 29, 2007 on PSN. Warner/Reprise Track Pack - Released December 20, 2007 on XBL and January 3, 2007 on PSN. Classic Rock Track Pack - Released January 24, 2008 on XBL and PSN.
No Doubt Track Pack - Released Febuary 28, 2008 on XBL and PSN. Modern Metal Track Pack - Released March 6, 2008 on XBL & PSN. Dropkick Murphys Track Pack - Released March 13, 2008 on XBL & PSN. Def Leppard Track Pack - Released April 24, 2008 on XBL & PSN.
Guitar Virtuoso Pack - Released July 24, 2008 on XBL & PSN. DragonForce Track Pack - Released August 21, 2008 on XBL & PSN Powered USB uses standard USB signaling with the addition of extra power lines. It uses 4 additional pins to supply up to 6A at either 5V, 12V, or 24V (depending on keying) to peripheral devices. The wires and contacts on the USB portion have been upgraded to support higher current on the 5V line, as well. This is commonly used in retail systems and provides enough power to operate stationary barcode scanners, printers, pin pads, signature capture devices, etc. This proprietary implementation was developed by IBM, NCR, and FCI/Berg. It is essentially two connectors stacked such that the bottom connector accepts a standard USB plug and the top connector takes a power connector. USB compared with FireWireUSB was originally seen as a complement to FireWire (IEEE 1394), which was designed as a high-speed serial bus which could efficiently interconnect peripherals such as hard disks, audio interfaces, and video equipment. USB originally operated at a far lower data rate and used much simpler hardware, and was suitable for small peripherals such as keyboards and mice. The most significant technical differences between FireWire and USB include the following:
These and other differences reflect the differing design goals of the two buses: USB was designed for simplicity and low cost, while FireWire was designed for high performance, particularly in time-sensitive applications such as audio and video. Although similar in theoretical maximum transfer rate, FireWire 400 tends to have the performance edge over USB 2.0 Hi-Speed in real-world uses, especially in high-bandwidth use such as external hard-drives.[27][28][29][30] The newer FireWire 800 standard is twice as fast as FireWire 400 and outperforms USB 2.0 Hi-Speed both theoretically and practically.[31] The chipset and drivers used to implement USB and Firewire have a crucial impact on how much of the bandwidth prescribed by the specification is achieved in the real world, along with compatibility with peripherals.[32] Audio peripherals in particular are affected by the USB driver implementation.Template:Fact Initially, cost was significant in USB being more widespread than FireWire. Over time, USB benefited from network effect. Version historyPrereleases
USB 1.0
USB 2.0Image:Certified Hi-Speed USB.svg
USB 3.0Image:USB30Logo.jpg Image:USB30icon.JPG On September 18, 2007, Pat Gelsinger demonstrated USB 3.0 at the Intel Developer Forum. The USB 3.0 Promoter Group announced on November 17, 2008, that version 1.0 of the specification has been completed and is transitioned to the USB Implementers Forum (USB-IF), the managing body of USB specifications. This move effectively opens the spec to hardware developers for implementation in future products. A new major feature is SuperSpeed bus, which increases the maximum transfer rate to 5.0 Gbit/s. [33] USB 3.0 receptacles are compatible with USB 2.0 device plugs for the respective physical form factors. However, only USB 3.0 Standard-B receptacles can accept USB 3.0 Standard-B device plugs. The protocol uses Dual-simplex, over four additional wires, differential signaling separate from USB 2.0 signaling (thus six wires total) to achieve the full Superspeed 5.0Gbps[34] The protocol supports full-duplex data transfers.[35] In addition, data transaction is based on asynchronous traffic flow with explicitly routed packet traffic, instead of the polled broadcast packet traffic in USB 2.0. A streams mode is added for bulk transfer mode. SuperSpeed protocol also supports continuous burst transfers. New power management features include support of idle, sleep and suspend states[34], as well as link and function-level power management. Maximum bus power is increased to 150mA per unit load (+50% over USB 2.0). An unconfigured device can still draw only 1 unit load, but a configured device can draw up to 6 unit loads (900mA, an 80% increase over USB 2.0). Minimum device operating voltage is dropped from 4.4V to 4V.[34] USB 3.0 does not define cable assembly lengths, except that it can be of any length as long as it meets all the requirements defined in the specification. However, electronicdesign.com estimated cables will be limited to 3 m at full speed.[18] The technology is similar to PCI Express 2.0 (5-Gbit/s). It uses 8B10B encoding, linear feedback shift register (LFSR) scrambling for data, spread spectrum. It forces receivers to use low frequency periodic signaling (LFPS), dynamic equalization, and training sequences to ensure fast signal locking. AvailabilityUSB 3.0 devices supporting SuperSpeed bus are expected to be available in commercial controllers in the second half of 2009. Consumer products are expected to become available in 2010.[36] Windows 7 and Linux drivers are under development but no public releases available yet as of January 2009. [37] Related technologiesThe PictBridge standard allows for interconnecting consumer imaging devices. It typically uses USB for its underlying communication layer. The USB Implementers Forum is working on a wireless networking standard based on the USB protocol. Wireless USB is intended as a cable-replacement technology, and will use ultra-wideband wireless technology for data rates of up to 480 Mbit/s. Wireless USB is well suited to wireless connection of PC centric devices, just as Bluetooth is now widely used for mobile phone centric personal networks (at much lower data rates). See also
ReferencesExternal linksTemplate:Commonscat Template:Wikibookspar
USB 3.0
ar:ناقل متسلسل عام bs:USB br:Porzh USB bg:USB ca:Bus sèrie universal cs:Universal Serial Bus da:Universal Serial Bus de:Universal Serial Bus el:USB es:Universal Serial Bus eo:Universala seria buso eu:USB fa:همهگذر fr:Universal Serial Bus gl:USB ko:범용 직렬 버스 hi:यू एस बी hsb:Universal Serial Bus hr:USB id:Universal Serial Bus it:Universal Serial Bus he:Universal Serial Bus lv:Universal Serial Bus lb:Universal Serial Bus lt:USB lmo:USB hu:Universal Serial Bus ms:Bas Bersiri Semesta nl:Universal Serial Bus ja:Universal Serial Bus no:USB nn:Universal Serial Bus pl:USB pt:Universal Serial Bus ro:USB ru:USB sq:USB scn:USB simple:Universal Serial Bus sk:Univerzálna sériová zbernica sl:Univerzalno serijsko vodilo sr:USB su:Universal Serial Bus fi:USB sv:Universal Serial Bus tl:Universal Serial Bus th:ยูเอสบี vi:USB tr:USB uk:USB ur:کائناتی سلسلی حافلہ yi:USB zh-yue:USB zh:USB
|
Universal Serial Bus
| This page was last modified on 22 January 2009, at 17:58. This page has been accessed 23,899 times. Disclaimers |
Powered by MediaWiki © Wikimedia