115-600: Universal Serial Bus 4 ( USB4 ), sometimes erroneously referred to as USB 4.0 , is the most recent technical specification of the USB (Universal Serial Bus) data communication standard. The USB Implementers Forum originally announced USB4 in 2019. USB4 enables multiple devices to dynamically share a single high-speed data link . USB4 devices must support a signaling rate of at least 20 Gbit/s. The current version allows signalling rates of 40 Gbit/s (since USB4, first version) and 80 Gbit/s (since USB4 version 2.0). USB4
230-399: A spread-spectrum clock varying by up to 5000 ppm at 33 KHz to reduce EMI. As a result, the receiver needs to continually "chase" the clock to recover the data. Clock recovery is helped by the 8b/10b encoding and other designs. The "SuperSpeed" bus provides for a transfer mode at a nominal rate of 5.0 Gbit/s, in addition to the three existing transfer modes. Accounting for
345-456: A "Lane" as a (bidirectional) connection, which for all recent transmission modes consists of one sending and one receiving wire-pair. The "Gen AxB" notation refers to B Lanes of operation mode A. Since Gen 4 modes also introduced asymmetric connections with uneven numbers of wire-pairs dedicated to sending and receiving, the Lane-notation is no longer applicable. The USB 3.x family has had
460-434: A PCI Express expansion card . In addition to an empty PCIe slot on the motherboard, many "PCI Express to USB 3.0" expansion cards must be connected to a power supply such as a Molex adapter or external power supply, in order to power many USB 3.0 devices such as mobile phones, or external hard drives that have no power source other than USB; as of 2011, this is often used to supply two to four USB 3.0 ports with
575-535: A STALL handshake. If there is lack of buffer space or data, it responds with a Not Ready (NRDY) signal to tell the host that it is not able to process the request. When the device is ready, it sends an Endpoint Ready (ERDY) to the host which then reschedules the transaction. The use of unicast and the limited number of multicast packets, combined with asynchronous notifications, enables links that are not actively passing packets to be put into reduced power states, which allows better power management. USB 3.0 uses
690-433: A USB 2.0 Standard-A plug. Conversely, it is possible to plug a USB 3.0 Standard-A plug into a USB 2.0 Standard-A receptacle. This is a principle of backward compatibility. The Standard-A plug is used for connecting to a computer port, at the host side. A USB 3.0 Standard-B receptacle accepts either a USB 3.0 Standard-B plug or a USB 2.0 Standard-B plug. Backward compatibility applies to connecting
805-468: A USB 2.0 Standard-B plug into a USB 3.0 Standard-B receptacle. However, it is not possible to plug a USB 3.0 Standard-B plug into a USB 2.0 Standard-B receptacle, due to the physically larger connector. The Standard-B plug is used at the device side. Since USB 2.0 and USB 3.0 ports may coexist on the same machine and they look similar, the USB ;3.0 specification recommends that
920-521: A USB4 connection is achieved by tunneling of other protocols. This includes tunneling of USB 3.2 Gen 2 and DisplayPort. Other optional protocols, such as PCI Express and Ethernet can also be tunneled. USB4 is based on the Thunderbolt 3 protocol; however, the implementation of Thunderbolt 3 protocol is mandatory only for hubs. Prior to USB4, Thunderbolt provided a way to dynamically share bandwidth between multiple DP and PCIe connections over
1035-570: A USB4 downward facing port is backwards compatible to all previous USB devices. USB 2.0 defines 3 different signalling rates (Low-, Full-, High-Speed), all are required to be supported. USB 2.0 abilities uses separate wires on the Type-C connector that are not used by USB 3.2 or USB4. USB 3.2 defines 3 different signaling rates ("5 Gbps" a.k.a. SuperSpeed, "10 Gbps" a.k.a. SuperSpeed+, "20 Gbps" a.k.a. SuperSpeed+ 20 Gbps). While USB 3.2 specification has been functionally supported by USB4, only
1150-538: A USB4 port guarantees. Since USB4 uses the Type-C connector , which was designed to be multifunctional and reversable, the term "host" port does not accurately reflect the situation. This is better denoted as a downward facing port (DFP). The peripheral side can similarly be described as upward facing port (UFP). Any downward facing USB4 port is required to also implement USB 2.0, USB 3.2 and DP Alternative Mode support. Each according to their own specifications. As such
1265-445: A built-in hub that connects to the physical USB cable. USB device communication is based on pipes (logical channels). A pipe connects the host controller to a logical entity within a device, called an endpoint . Because pipes correspond to endpoints, the terms are sometimes used interchangeably. Each USB device can have up to 32 endpoints (16 in and 16 out ), though it is rare to have so many. Endpoints are defined and numbered by
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#17328557606751380-408: A caption stylized as SUPERSPEED+ ; this refers to the updated SuperSpeedPlus protocol. The USB 3.1 Gen 2 mode also reduces line encoding overhead to just 3% by changing the encoding scheme to 128b/132b , with raw data rate of 1,212 MB/s. The first USB 3.1 Gen 2 implementation demonstrated real-world transfer speeds of 7.2 Gbit/s. The USB 3.1 specification includes
1495-536: A larger PCIe packet can be split across multiple USB4 packets. Support for this new feature requires every USB4 component / controller involved in the PCIe tunnel to implement USB4 Version 2.0. Signaling refers to the lowest layer of the OSI Model , also called physical layer or phy. USB4 connections can be expressed with consumer facing names that are also the basis for the official logos used on packaging and products. These are
1610-653: A new coding schema (128b/132b symbols, 10 Gbit/s; also known as Gen 2 ); for some time marketed as SuperSpeed+ ( SS+ ). The USB 3.2 specification added a second lane to the Enhanced SuperSpeed System besides other enhancements so that the SuperSpeedPlus USB system part implements the Gen 1×2 , Gen 2×1, and Gen 2×2 operation modes. However, the SuperSpeed USB part of the system still implements
1725-461: A payload of up to 256 Byte per USB4 packet and a PCIe tunnel packet contains further PCIe headers and meta data, the MPS for PCIe tunnels was limited to 128 Byte. This limitation can reduce the efficiency of the PCIe connection greatly for all devices and systems that would otherwise support 256 Byte or even larger MPS. USB4 Version 2.0 removes this bottleneck (mandatory for all implementers), by defining how
1840-556: A pending update to the USB Type-C specification, defining the doubling of bandwidth for existing USB-C cables. Under the USB 3.2 specification, released 22 September 2017, existing SuperSpeed certified USB-C 3.1 Gen 1 cables will be able to operate at 10 Gbit/s (up from 5 Gbit/s), and SuperSpeed+ certified USB-C 3.1 Gen 2 cables will be able to operate at 20 Gbit/s (up from 10 Gbit/s). The increase in bandwidth
1955-485: A regular, physical connection again, most of those physical limitations, like max. bandwidth are still likely to apply in the end. This is a single-hop tunnel that essentially can transport any Enhanced SuperSpeed connection according to the USB 3.2 specification. USB3 Gen X follows the Enhanced SuperSpeed Hub topology, where every USB4 router with more than one USB3 endpoint must include a USB3 hub as well. It
2070-487: A single PCI Express 5 GT/s lane (among other features), thus obtaining the necessary bandwidth from the PCH. USB 3.0 devices and cables may interfere with wireless devices operating in the 2.4 GHz ISM band. This may result in a drop in throughput or complete loss of response with Bluetooth and Wi-Fi devices. When manufacturers were unable to resolve the interference issues in time, some mobile devices, such as
2185-405: A single cable. Thunderbolt originally used the mDP connector and was only backward compatible to DP connections and did not support power transfer. The introduction of the Type-C connector in 2014 provided a connector that could support both USB data connectivity, power transfer as well as DP connections. It also allowed the static sharing of bandwidth between DP and USB connections over
2300-531: A single upstream USB3 connection and distribute its bandwidth across all its downstream facing ports that make use of USB3 connections. This is an optional alternative to USB3 Gen X tunneling that was introduced in USB4 Version 2.0. It is an end-to-end variant of USB3 Gen X tunnel. Through this, it eschews the need for USB3 hubs in every USB4 router that can and will limit the throughput. It allows multiple separate USB3 Gen T tunnels even over shared links. Since it
2415-534: A standard to replace virtually all common ports on computers, mobile devices, peripherals, power supplies, and manifold other small electronics. In the current standard, the USB-C connector replaces the many various connectors for power (up to 240 W), displays (e.g. DisplayPort, HDMI), and many other uses, as well as all previous USB connectors. As of 2024, USB consists of four generations of specifications: USB 1. x , USB 2.0 , USB 3. x , and USB4 . USB4 enhances
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#17328557606752530-434: A tactic by Intel to favor its new Thunderbolt interface. Apple, Inc. announced laptops with USB 3.0 ports on 11 June 2012, nearly four years after USB 3.0 was finalized. AMD began supporting USB 3.0 with its Fusion Controller Hubs in 2011. Samsung Electronics announced support of USB 3.0 with its ARM -based Exynos 5 Dual platform intended for handheld devices. Various early USB 3.0 implementations widely used
2645-574: A tethered connection (that is: no plug or receptacle at the peripheral end). There was no known miniature type A connector until USB 2.0 (revision 1.01) introduced one. USB 2.0 was released in April 2000, adding a higher maximum signaling rate of 480 Mbit/s (maximum theoretical data throughput 53 MByte/s ) named High Speed or High Bandwidth , in addition to the USB 1. x Full Speed signaling rate of 12 Mbit/s (maximum theoretical data throughput 1.2 MByte/s). Modifications to
2760-505: A tunnel typically entails removing any Phy/Electrical layer and encoding of the underlying connection standard and potentially losslessly compresses the contents, for example by leaving out empty filler data. A USB4 tunnel itself is virtual and need not conform to any fixed bandwidth or other limitations that stem from the Phy/Electric layer of the underlying connection standard. But since most tunnel types will eventually be converted back to
2875-421: A tunnel. USB4 defines the following tunnel types: USB4 forms a tree-like topology of USB4 routers (each USB4 device includes a USB4 router to participate in this network). A tunnel can be end-to-end, where the route through the entire network of routers is preconfigured. But tunnels can also be single-hop, where it exists only for a single USB4 link (between 2 routers). In this case the tunnel will be "unpacked" by
2990-525: Is full duplex whereas USB 2.0 is half duplex . This gives USB 3.0 a potential total bidirectional bandwidth twenty times greater than USB 2.0. Considering flow control, packet framing and protocol overhead, applications can expect 450 MB/s of bandwidth. In USB 3.0, dual-bus architecture is used to allow both USB 2.0 (Full Speed, Low Speed, or High Speed) and USB 3.0 (SuperSpeed) operations to take place simultaneously, thus providing backward compatibility . The structural topology
3105-500: Is full-duplex ; all earlier implementations, USB 1.0-2.0, are all half-duplex, arbitrated by the host. Low-power and high-power devices remain operational with this standard, but devices implementing SuperSpeed can provide increased current of between 150 mA and 900 mA, by discrete steps of 150 mA. USB 3.0 also introduced the USB Attached SCSI protocol (UASP) , which provides generally faster transfer speeds than
3220-592: Is 150 mA, an increase from the 100 mA defined in USB 2.0. For high-power SuperSpeed devices, the limit is six unit loads or 900 mA (4.5 W )—almost twice USB 2.0's 500 mA. USB 3.0 ports may implement other USB specifications for increased power, including the USB Battery Charging Specification for up to 1.5 A or 7.5 W, or, in the case of USB 3.1, the USB Power Delivery Specification for charging
3335-541: Is IN while the TOKEN packet is an OUT packet), the TOKEN packet is ignored. Otherwise, it is accepted and the data transaction can start. A bi-directional endpoint, on the other hand, accepts both IN and OUT packets. USB 3.0 Universal Serial Bus 3.0 ( USB 3.0 ), marketed as SuperSpeed USB , is the third major version of the Universal Serial Bus (USB) standard for interfacing computers and electronic devices. It
3450-860: Is allowed to strip most of the backwards compatibility away. The Gen 4 transmission mode, with PAM-3 uses very different signaling to previous modes. Every active components needs to explicitly support this new signaling. But it stays within all signal quality requirements of existing, passive Gen 3 cables (USB4 and TB3). USB Universal Serial Bus ( USB ) is an industry standard , developed by USB Implementers Forum (USB-IF), that allows data exchange and delivery of power between many types of electronics. It specifies its architecture, in particular its physical interface , and communication protocols for data transfer and power delivery to and from hosts , such as personal computers , to and from peripheral devices , e.g. displays, keyboards, and mass storage devices, and to and from intermediate hubs , which multiply
3565-463: Is also tunneled as end-to-end connection. There can be multiple independent DP tunnels, but each will be delivered to a single protocol output adapter (at which point DisplayPort MST might be used to further split each connection up). USB4 Version 1.0 only defines how to tunnel DP connections according to the DisplayPort 1.4a specification (up to HBR3 speeds). USB4 Version 2.0 updates this support to
USB4 - Misplaced Pages Continue
3680-554: Is an end-to-end tunnel, every USB4 hub will support passing it through. USB3 Gen T is intended as exclusively virtual, there exists no physical equivalent for it. Thus, it can only be used inside of a USB4 controller. This allows it to leave the limitations to 10 or 20 Gbit/s connections of USB 3.2 behind, while reusing most of the other parts of the Enhanced SuperSpeed protocol . No known USB4 controller implements support for Gen T tunneling to date (August 2024). DisplayPort
3795-464: Is backward compatible with the Micro USB ;2.0 plug. A receptacle for eSATAp , which is an eSATA/USB combo, is designed to accept USB Type-A plugs from USB 2.0 (or earlier), so it also accepts USB 3.0 Type-A plugs. In January 2013 the USB group announced plans to update USB 3.0 to 10 Gbit/s (1250 MB/s). The group ended up creating a new USB specification, USB 3.1, which
3910-801: Is for drain wire termination and to control EMI and maintain signal integrity. USB 3.0 and USB 2.0 (or earlier) Type-A plugs and receptacles are designed to interoperate. USB 3.0 Type-B receptacles, such as those found on peripheral devices, are larger than in USB 2.0 (or earlier versions), and accept both the larger USB 3.0 Type-B plug and the smaller USB 2.0 (or earlier) Type-B plug. USB 3.0 Type-B plugs are larger than USB 2.0 (or earlier) Type-B plugs; therefore, USB 3.0 Type-B plugs cannot be inserted into USB 2.0 (or earlier) Type-B receptacles. Micro USB 3.0 (Micro-B) plug and receptacle are intended primarily for small portable devices such as smartphones, digital cameras and GPS devices. The Micro USB 3.0 receptacle
4025-549: Is implemented using a free-running linear feedback shift register (LFSR). The LFSR is reset whenever a COM symbol is sent or received. Unlike previous standards, the USB 3.0 standard does not specify a maximum cable length, requiring only that all cables meet an electrical specification: for copper cabling with AWG 26 wires, the maximum practical length is 3 meters (10 ft). As with earlier versions of USB, USB 3.0 provides power at 5 volts nominal. The available current for low-power (one unit load) SuperSpeed devices
4140-402: Is made using two connectors: a receptacle and a plug . Pictures show only receptacles: The Universal Serial Bus was developed to simplify and improve the interface between personal computers and peripheral devices, such as cell phones, computer accessories, and monitors, when compared with previously existing standard or ad hoc proprietary interfaces. From the computer user's perspective,
4255-531: Is only defined for USB-C connectors and its Type-C specification regulates the connector, cables and also power delivery features across all uses of USB-C cables, in part with the USB Power Delivery specification. The USB4 standard mandates functionally backwards compatibility to USB 3.2 (which supersedes USB 3.0 and USB 3.1) and dedicated backward compatibility with USB 2.0 (and therefore subsequently USB 2.0/1.1). The dynamic sharing of bandwidth of
4370-458: Is the default way USB3 connections through USB4 are made. Supporting it at 10 Gbit/s (SuperSpeed USB 10 Gbps, Gen 2x1) is mandatory on every USB4 DFP . The minimum supported speed for the USB3 connection being tunneled is 10 Gbit/s as every USB4 device already has to support this speed and USB3 hubs handle converting this to 5 Gbit/s devices that may be connected. This means, that a USB4 hub will share
4485-413: Is the same, consisting of a tiered star topology with a root hub at level 0 and hubs at lower levels to provide bus connectivity to devices. The SuperSpeed transaction is initiated by a host request, followed by a response from the device. The device either accepts the request or rejects it; if accepted, the device sends data or accepts data from the host. If the endpoint is halted, the device responds with
4600-1044: The Gen ;2x1 (formerly known as USB 3.1 Gen 2 ), and the two new Gen 1x2 and Gen 2x2 operation modes while operating on two lanes. The SuperSpeed architecture and protocol (aka SuperSpeed USB) still implements the one-lane Gen 1x1 (formerly known as USB 3.1 Gen 1 ) operation mode. Therefore, two-lane operations, namely USB 3.2 Gen 1x2 (10 Gbit/s with raw data rate of 1 GB/s after encoding overhead) and USB 3.2 Gen 2x2 (20 Gbit/s, 2.422 GB/s), are only possible with Full-Featured USB Type-C Fabrics (24 pins). As of 2023, USB 3.2 Gen 1x2 and Gen 2x2 are not implemented on many products yet; Intel, however, starts to include them in its LGA 1200 Rocket Lake chipsets (500 series) in January 2021 and AMD in its LGA 1718 AM5 chipsets in September 2022, but Apple never provided them. On
4715-487: The HP Envy 17 3D featuring a Renesas USB 3.0 host controller several months before some of their competitors. AMD worked with Renesas to add its USB 3.0 implementation into its chipsets for its 2011 platforms. At CES2011, Toshiba unveiled a laptop called " Qosmio X500" that included USB 3.0 and Bluetooth 3.0 , and Sony released a new series of Sony VAIO laptops that would include USB 3.0. As of April 2011,
USB4 - Misplaced Pages Continue
4830-554: The Inspiron and Dell XPS series were available with USB 3.0 ports, and, as of May 2012, the Dell Latitude laptop series were as well; yet the USB root hosts failed to work at SuperSpeed under Windows 8. Additional power for multiple ports on a laptop PC may be obtained in the following ways: On the motherboards of desktop PCs which have PCI Express (PCIe) slots (or the older PCI standard), USB 3.0 support can be added as
4945-624: The NEC / Renesas μD72020x family of host controllers, which are known to require a firmware update to function properly with some devices. A factor affecting the speed of USB storage devices (more evident with USB 3.0 devices, but also noticeable with USB 2.0 ones) is that the USB Mass Storage Bulk-Only Transfer (BOT) protocol drivers are generally slower than the USB Attached SCSI protocol (UAS[P]) drivers. On some old (2009–2010) Ibex Peak -based motherboards,
5060-653: The USB Implementers Forum (USB-IF). At least one complete end-to-end test system for USB 3.0 designers is available on the market. The USB Promoter Group announced the release of USB 3.0 in November 2008. On 5 January 2010, the USB-IF announced the first two certified USB 3.0 motherboards, one by ASUS and one by Giga-Byte Technology . Previous announcements included Gigabyte's October 2009 list of seven P55 chipset USB 3.0 motherboards, and an Asus motherboard that
5175-508: The "20 Gbps", "40 Gbps", "80 Gbps" labels and they do not explicitly indicate how the connection is achieved on the physical layer. There are also more technical names based on the implementation and use of the USB-C cables. These usually consist of a speed per wire-pair expressed as Gen 1/2/3/4 (5 Gbit/s, 10 Gbit/s, 20 Gbit/s, 40 Gbit/s respectively) and some further information on how many wire-pairs are used in which combination. USB commonly defines
5290-525: The 2 lower speeds (5 Gbit/s, 10 Gbit/s) are mandatory for USB4 DFPs to support. The USB4 specifications make no reference to a minimum feature set for its DP Alternative Mode, but Thunderbolt 3 does. In practice, Intel's family of TB 3 controllers requires DisplayPort 1.2 , it also support up to HBR3 speeds according to the DisplayPort 1.4a specification and DisplayPort Alt Mode specification . The USB4 specification makes no explicit demands on power output. It outsources all requirements in terms of power to
5405-485: The 5, 10, and 20 Gbit/s capabilities as SuperSpeed USB 5Gbps , SuperSpeed USB 10 Gbps , and SuperSpeed USB 20 Gbps , respectively. In 2023, they were replaced again, removing "SuperSpeed" , with USB 5Gbps , USB 10Gbps , and USB 20Gbps . With new Packaging and Port logos. The USB4 specification was released on 29 August 2019 by the USB Implementers Forum. The USB4 2.0 specification
5520-538: The BOT (Bulk-Only-Transfer) protocol. USB 3.1 , released in July 2013 has two variants. The first one preserves USB 3.0's SuperSpeed architecture and protocol and its operation mode is newly named USB 3.1 Gen 1 , and the second version introduces a distinctively new SuperSpeedPlus architecture and protocol with a second operation mode named as USB 3.1 Gen 2 (marketed as SuperSpeed+ USB ). SuperSpeed+ doubles
5635-454: The Gen ;2 operation mode are of roughly below 800 MB/s for reading bulk transfers only. The re-specification of USB 3.0 as "USB 3.1 Gen 1" was misused by some manufacturers to advertise products with signaling rates of only 5 Gbit/s as "USB 3.1" by omitting the defining generation. On 25 July 2017, a press release from the USB 3.0 Promoter Group detailed
5750-630: The Las Vegas Consumer Electronics Show (CES), including two motherboards by Asus and Gigabyte Technology . Manufacturers of USB 3.0 host controllers include, but are not limited to, Renesas Electronics , Fresco Logic, ASMedia , Etron, VIA Technologies , Texas Instruments , NEC and Nvidia . As of November 2010, Renesas and Fresco Logic have passed USB-IF certification. Motherboards for Intel 's Sandy Bridge processors have been seen with Asmedia and Etron host controllers as well. On 28 October 2010, Hewlett-Packard released
5865-474: The Standard-A USB ;3.0 receptacle have a blue insert ( Pantone 300C color). The same color-coding applies to the USB 3.0 Standard-A plug. USB 3.0 also introduced a new Micro-B cable plug, which consists of a standard USB 1.x/2.0 Micro-B cable plug, with an additional 5-pin plug "stacked" beside it. That way, the USB 3.0 Micro-B host receptacle preserves its backward compatibility with
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#17328557606755980-487: The SuperSpeed USB Developers Conference. USB 3.0 adds a new architecture and protocol named SuperSpeed , with associated backward-compatible plugs, receptacles, and cables. SuperSpeed plugs and receptacles are identified with a distinct logo and blue inserts in standard format receptacles. The SuperSpeed architecture provides for an operation mode at a rate of 5.0 Gbit/s, in addition to
6095-543: The SuperSpeed architecture and protocol (aka SuperSpeed USB ) – with an additional SuperSpeedPlus architecture adding and providing a new coding schema (128b/132b symbols) and protocol named SuperSpeedPlus (aka SuperSpeedPlus USB , sometimes marketed as SuperSpeed+ or SS+ ) while defining a new transfer mode called USB 3.1 Gen 2 with a signal speed of 10 Gbit/s and a raw data rate of 1212 MB/s over existing Type-A, Type-B, and USB-C connections, more than twice
6210-469: The Type-C specification that underpins all USB, Vesa and other standards that use the USB-C connector. This requires a USB4 DFP to supply at least 7.5W Type-C current. No power consumption features (e.g. charging of a notebook) are required, but can be supported following the USB PD specification. as well as supplying considerably more power. The USB PD protocol must always be supported (exchanging data according to
6325-699: The USB 1.x/2.0 Micro-B cable plug, allowing devices with USB 3.0 Micro-B ports to run at USB 2.0 speeds on USB 2.0 Micro-B cables. However, it is not possible to plug a USB 3.0 Micro-B plug into a USB 2.0 Micro-B receptacle, due to the physically larger connector. The connector has the same physical configuration as its predecessor but with five more pins. The VBUS, D−, D+, and GND pins are required for USB 2.0 communication. The five additional USB 3.0 pins are two differential pairs and one ground (GND_DRAIN). The two additional differential pairs are for SuperSpeed data transfer; they are used for full duplex SuperSpeed signaling. The GND_DRAIN pin
6440-405: The USB 2.0 bus operating in parallel. The USB 3.0 specification defined a new architecture and protocol named SuperSpeed (aka SuperSpeed USB , marketed as SS ), which included a new lane for a new signal coding scheme (8b/10b symbols, 5 Gbit/s; later also known as Gen 1 ) providing full-duplex data transfers that physically required five additional wires and pins, while preserving
6555-400: The USB 2.0 specification while fully preserving its dedicated physical layer, architecture, and protocol in parallel. USB 3.1 specification defines the following operation modes: The nominal data rate in bytes accounts for bit-encoding overhead. The physical SuperSpeed signaling bit rate is 5 Gbit/s. Since transmission of every byte takes 10 bit times, the raw data overhead is 20%, so
6670-416: The USB interface improves ease of use in several ways: The USB standard also provides multiple benefits for hardware manufacturers and software developers, specifically in the relative ease of implementation: As with all standards, USB possesses multiple limitations to its design: For a product developer, using USB requires the implementation of a complex protocol and implies an "intelligent" controller in
6785-401: The USB specification have been made via engineering change notices (ECNs). The most important of these ECNs are included into the USB 2.0 specification package available from USB.org: The USB 3.0 specification was released on 12 November 2008, with its management transferring from USB 3.0 Promoter Group to the USB Implementers Forum (USB-IF) and announced on 17 November 2008 at
6900-541: The USB 2.0 architecture and protocols and therefore keeping the original four pins/wires for the USB 2.0 backward-compatibility resulting in 9 wires (with 9 or 10 pins at connector interfaces; ID-pin is not wired) in total. The USB 3.1 specification introduced an Enhanced SuperSpeed System – while preserving the SuperSpeed architecture and protocol ( SuperSpeed USB ) – with an additional SuperSpeedPlus architecture and protocol (aka SuperSpeedPlus USB ) adding
7015-524: The USB4 Gen 2 and Gen 3 modes use very similar signaling, however, Thunderbolt 3 runs at slightly higher speeds called legacy speeds compared to rounded speeds of USB4. It is driven slightly faster at 10.3125 Gbit/s (for Gen 2) and 20.625 Gbit/s (for Gen 3), as required by Thunderbolt specifications. USB4 Gen 4 is normally referred to as a speed of "40 Gbps" or 40 Gbit/s, with the full connections based on it being referred to as 80, 120/40, 40/120 Gbit/s. But since
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#17328557606757130-414: The USB4 Version 2.0 specification. It added 80 Gbit/s signalling rate with optionally asymmetric signaling, a new, optional alternative to the existing "USB3 Gen T tunneling", removed PCIe overhead limitations and updated the support of DisplayPort to the then current Version 2.1. Around the release of the new USB4 2.0 specification, USB-IF also mandated new logos and marketing names to simplify representing
7245-488: The USB4 protocol/connections, which is a distinct standard to establish USB4 links / connections between USB4 devices that exists in parallel to previous USB protocols. Unlike USB 2.0 and USB 3.x it does not provide a way to transfer data directly, but rather it is a mere container that can contain multiple "tunnels"/virtual connections. Other specifications are referenced to define the contents and internal functionality of
7360-430: The USB4 router where the data is ingested into the tunnel and at the target, the point where the tunnel ends. A Protocol Input Adapter will ingest a connection according to whatever protocol it is based on and convert the contents into a USB4 tunnel. Protocol Output Adapters do the reverse. They extract a tunnel from the USB4 network and if needed recreate a regular connection from the tunnel contents. The conversion into
7475-467: The Vivo Xplay 3S, had to drop support for USB 3.0 just before they shipped. Various strategies can be applied to resolve the problem, ranging from simple solutions such as increasing the distance of USB 3.0 devices from Wi-Fi and Bluetooth devices, to applying additional shielding around internal computer components. A USB 3.0 Standard-A receptacle accepts either a USB 3.0 Standard-A plug or
7590-469: The actual signaling no longer is binary, the actual raw bit rates no longer match those numbers exactly. A USB4 hub is defined by having 1 USB4 UFP and one or more USB4 DFP . A USB4-based dock is defined as a USB4 hub that also has more specialized outputs like HDMI or DP, but still keeping some USB4 DFP. A USB4 peripheral device is defined by not having any USB4 DFP. This means devices that are colloquially called "USB-C hubs" may use USB4 to support
7705-578: The built-in USB 3.0 chipsets are connected by default via a 2.5 GT/s PCI Express lane of the PCH , which then did not provide full PCI Express 2.0 speed (5 GT/s), so it did not provide enough bandwidth even for a single USB 3.0 port. Early versions of such boards (e.g. the Gigabyte Technology P55A-UD4 or P55A-UD6) have a manual switch (in BIOS) that can connect the USB 3.0 chip to
7820-746: The data transfer and power delivery functionality with ... a connection-oriented, tunneling architecture designed to combine multiple protocols onto a single physical interface so that the total speed and performance of the USB4 Fabric can be dynamically shared. USB4 particularly supports the tunneling of the Thunderbolt 3 protocols, namely PCI Express (PCIe, load/store interface) and DisplayPort (display interface). USB4 also adds host-to-host interfaces. Each specification sub-version supports different signaling rates from 1.5 and 12 Mbit/s total in USB 1.0 to 80 Gbit/s (in each direction) in USB4. USB also provides power to peripheral devices;
7935-506: The development of USB in 1995: 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 connectors at 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 data transfer rates for external devices and plug and play features. Ajay Bhatt and his team worked on
8050-402: The device during initialization (the period after physical connection called "enumeration") and so are relatively permanent, whereas pipes may be opened and closed. There are two types of pipe: stream and message. When a host starts a data transfer, it sends a TOKEN packet containing an endpoint specified with a tuple of (device_address, endpoint_number) . If the transfer is from the host to
8165-461: The different families of standards (USB&2.0, USB 3.2, USB4). The USB4 standard mandates that classic active or hybrid active cables still have vast backward compatibility support, so as to behave as if they were regular, passive cables in the eyes of the consumer. But forward compatibility is limited for active cables. Only Optically Isolated Active Cables (OIAC), that should be clearly distinguishable (price, design, cable thickness, advertising)
8280-487: The dynamic bandwidth sharing or higher bandwidths of USB4. But they are not USB4 hubs if they do not have any USB4 DFP. Not having any USB4 DFP allows the peripheral to only support exactly those USB4 features that it has uses for, potentially simplifying its implementation considerably. connection USB4 networking (Low-, Full-, High-Speed) The Type-C standard supports cable backward / downward compatibility in many situations. The compatibility typically only breaks between
8395-414: The encoding overhead, the raw data throughput is 4 Gbit/s, and the specification considers it reasonable to achieve 3.2 Gbit/s (400 MB/s) or more in practice. All data is sent as a stream of eight-bit (one-byte) segments that are scrambled and converted into 10-bit symbols via 8b/10b encoding ; this helps prevent transmissions from generating electromagnetic interference (EMI). Scrambling
8510-400: 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 packet instead. If the destination endpoint is a uni-directional endpoint whose manufacturer's designated direction does not match the TOKEN packet (e.g. the manufacturer's designated direction
8625-432: The following ECNs: A USB system consists of a host with one or more downstream facing ports (DFP), and multiple peripherals, forming a tiered- star topology . Additional USB hubs may be included, allowing up to five tiers. A USB host may have multiple controllers, each with one or more ports. Up to 127 devices may be connected to a single host controller. USB devices are linked in series through hubs. The hub built into
8740-430: The full DisplayPort 2.1 specification (up to UHBR20 speeds). DP tunneling has great understanding of the contents of DP connections, and will efficiently skip/transmit any filler data, reducing the actually utilized bandwidth of a DP tunnel. But since DP connections have real-time requirements , bandwidth must be reserved for them. USB4 mandates that in absence of any other information, the maximum possible bandwidth for
8855-648: The full 0.9 A (4.5 W) of power that each USB 3.0 port is capable of (while also transmitting data), whereas the PCI Express slot itself cannot supply the required amount of power. If faster connections to storage devices are the reason to consider USB 3.0, an alternative is to use eSATAp , possibly by adding an inexpensive expansion slot bracket that provides an eSATAp port; some external hard disk drives provide both USB (2.0 or 3.0) and eSATAp interfaces. To ensure compatibility between motherboards and peripherals, all USB-certified devices must be approved by
8970-448: The host controller is called the root hub . A USB device may consist of several logical sub-devices that are referred to as device functions . 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 a compound device , in which the host assigns each logical device a distinct address and all logical devices connect to
9085-579: The host device up to 100 W. Starting with the USB 3.2 specification, USB-IF introduced a new naming scheme. To help companies with branding of the different operation modes, USB-IF recommended branding the 5, 10, and 20 Gbit/s capabilities as SuperSpeed USB 5Gbps , SuperSpeed USB 10 Gbps , and SuperSpeed USB 20 Gbps , respectively. In 2023, they were replaced again, removing "SuperSpeed" , with USB 5Gbps , USB 10Gbps , and USB 20Gbps . With new Packaging and Port logos. The USB 3.0 Promoter Group announced on 17 November 2008 that
9200-964: The latest versions of the standard extend the power delivery limits for battery charging and devices requiring up to 240 watts ( USB Power Delivery (USB-PD) ). Over the years, USB(-PD) has been adopted as the standard power supply and charging format for many mobile devices, such as mobile phones, reducing the need for proprietary chargers. USB was designed to standardize the connection of peripherals to personal computers, both to exchange data and to supply electric power. It has largely replaced interfaces such as serial ports and parallel ports and has become commonplace on various devices. Peripherals connected via USB include computer keyboards and mice, video cameras, printers, portable media players, mobile (portable) digital telephones, disk drives, and network adapters. USB connectors have been increasingly replacing other types of charging cables for portable devices. USB connector interfaces are classified into three types:
9315-609: The many various legacy Type-A (upstream) and Type-B (downstream) connectors found on hosts , hubs , and peripheral devices , and the modern Type-C ( USB-C ) connector, which replaces the many legacy connectors as the only applicable connector for USB4. The Type-A and Type-B connectors came in Standard, Mini, and Micro sizes. The standard format was the largest and was mainly used for desktop and larger peripheral equipment. The Mini-USB connectors (Mini-A, Mini-B, Mini-AB) were introduced for mobile devices. Still, they were quickly replaced by
9430-539: The maximum signaling rate to 10 Gbit/s (later marketed as SuperSpeed USB 10 Gbps by the USB 3.2 specification), while reducing line encoding overhead to just 3% by changing the encoding scheme to 128b/132b . USB 3.2 , released in September 2017, preserves existing USB 3.1 SuperSpeed and SuperSpeedPlus architectures and protocols and their respective operation modes, but introduces two additional SuperSpeedPlus operation modes ( USB 3.2 Gen 1×2 and USB 3.2 Gen 2×2 ) with
9545-427: The maximum supported signalling rates and wattages to consumers. Similarly to how USB 3.x specifications defined the new SuperSpeed(Plus) protocols for faster signalling rates, but also mandated that USB 3.x physically and architecturally implement USB 2.0 specification with dedicated wires, the USB4 specification describes 2 different aspects. The first one is what type of existing connections and compatibility
9660-456: The new USB-C Fabric with signaling rates of 10 and 20 Gbit/s (raw data rates of 1212 and 2424 MB/s). The increase in bandwidth is a result of two-lane operation over existing wires that were originally intended for flip-flop capabilities of the USB-C connector. Starting with the USB 3.2 specification, USB-IF introduced a new naming scheme. To help companies with the branding of the different operation modes, USB-IF recommended branding
9775-452: The number of a host's ports. Introduced in 1996, USB was originally designed to standardize the connection of peripherals to computers, replacing various interfaces such as serial ports , parallel ports , game ports , and ADB ports. Early versions of USB became commonplace on a wide range of devices, such as keyboards, mice, cameras, printers, scanners, flash drives, smartphones, game consoles, and power banks. USB has since evolved into
9890-537: The one-lane Gen 1×1 operation mode. Therefore, two-lane operations, namely USB 3.2 Gen 1× 2 (10 Gbit/s) and Gen 2× 2 (20 Gbit/s), are only possible with Full-Featured USB-C. As of 2023, they are somewhat rarely implemented; Intel, however, started to include them in its 11th-generation SoC processor models, but Apple never provided them. On the other hand, USB 3.2 Gen 1(×1) (5 Gbit/s) and Gen 2(×1) (10 Gbit/s) have been quite common for some years. Each USB connection
10005-472: The optional functionality as Thunderbolt 4 products. USB4 2.0 with 80 Gbit/s speeds was to be revealed in November 2022. Further technical details were to be released at two USB developer days scheduled for November 2022. The USB4 specification states that the following technologies shall be supported by USB4: Because of the previous confusing naming schemes, USB-IF decided to change it once again. As of 2 September 2022, marketing names follow
10120-549: The original four pins and wires for the USB 2.0 backward-compatibility, resulting in nine wires in total and nine or ten pins at connector interfaces (ID-pin is not wired). The new transfer rate, marketed as SuperSpeed USB (SS), can transfer signals at up to 5 Gbit/s with raw data rate of 500 MB/s after encoding overhead, which is about 10 times faster than High-Speed (maximum for USB 2.0 standard). USB 3.0 Type-A and B connectors are usually blue, to distinguish them from USB 2.0 connectors, as recommended by
10235-472: The other hand, USB 3.2 Gen 1x1 (5 Gbit/s) and Gen 2x1 (10 Gbit/s) implementations have become quite common. Again, backward-compatibility is given by the parallel USB 2.0 implementation. The USB 3.0 specification is similar to USB 2.0 , but with many improvements and an alternative implementation. Earlier USB concepts such as endpoints and the four transfer types (bulk, control, isochronous and interrupt) are preserved but
10350-464: The particular DP connection (DP lanes and speed) must be reserved. This reservation only applies to other real-time tunnels though. Reserved, but unused bandwidth can be used by non-real-time tunnels such as PCIe or USB3, but the reservation may still block other DP tunnels from being established. Similar to USB3 Gen X tunneling, PCIe tunneling uses single-hop tunnels, requiring PCIe switches in every USB4 router that supports PCIe tunneling. USB4 has, from
10465-454: The peripheral device. Developers of USB devices intended for public sale generally must obtain a USB ID, which requires that they pay a fee to the USB Implementers Forum (USB-IF). Developers of products that use the USB specification must sign an agreement with the USB-IF. Use of the USB logos on the product requires annual fees and membership in the organization. A group of seven companies began
10580-540: The processor (instead of the PCH), which did provide full-speed PCI Express 2.0 connectivity even then, but this meant using fewer PCI Express 2.0 lanes for the graphics card. However, newer boards (e.g. Gigabyte P55A-UD7 or the Asus P7P55D-E Premium) used a channel bonding technique (in the case of those boards provided by a PLX PEX8608 or PEX8613 PCI Express switch) that combines two PCI Express 2.5 GT/s lanes into
10695-401: The protocol and electrical interface are different. The specification defines a physically separate channel to carry USB 3.0 traffic. The changes in this specification make improvements in the following areas: USB 3.0 has transmission speeds of up to 5 Gbit/s or 5000 Mbit/s, about ten times faster than USB 2.0 (0.48 Gbit/s) even without considering that USB 3.0
10810-474: The protocol. This is separate from any functionality of PD to negotiate actual power delivery other than 5V or > 15W). USB4 hubs and docks are defined as their own category of USB4 devices, that include further requirements. For example, a USB4 hub must also serve as a classic USB 3.2 hub with DP Alternative Mode passthrough with hosts that do not support USB4 connections. See USB4 capabilities by device type for more details. Every USB4 port must support
10925-499: The rate of USB 3.0 (aka Gen 1). Backward-compatibility is still given by the parallel USB 2.0 implementation. USB 3.1 Gen 2 Type-A and Type-B connectors are usually teal-colored. USB 3.2 , released in September 2017, fully replaces the USB 3.1 specification. The USB 3.2 specification added a second lane to the Enhanced SuperSpeed System besides other enhancements, so that SuperSpeedPlus USB implements
11040-401: The raw byte rate is 500 MB/s, not 625. Similarly, for Gen 2 link the encoding is 128b/132b, so transmission of 16 bytes physically takes 16.5 bytes, or 3% overhead. Therefore, the new raw byte-rate is 128/132 * 10 Gbit/s = 9.697 Gbit/s = 1212 MB/s. In reality any operation mode has additional link management and protocol overhead, so the best-case achievable data rates for
11155-455: The recipient and will use some other, tunnel type specific means to identify where the data needs to be sent next. If the next hop is another USB4 router, the data will be ingested again into the next single-hop tunnel until it exits the USB4 network. Accordingly, single-hop tunnels require specific support in each USB4 router to support even passing them through to further USB4 routers. End-to-end tunnels however only require specific support at
11270-564: The release of the Panther Point chipset. Some industry analysts have claimed that Intel was slow to integrate USB 3.0 into the chipset, thus slowing mainstream adoption. These delays may be due to problems in the CMOS manufacturing process, a focus to advance the Nehalem platform, a wait to mature all the 3.0 connections standards (USB 3.0, PCIe 3.0 , SATA 3.0 ) before developing a new chipset, or
11385-522: The same cable. Thunderbolt 3 switched over to using the new Type-C connector and also added backwards compatibility for USB connections and power transfer features. USB4 was announced in March 2019 by the USB Promoter Group. The first version of the USB4 specification, released 29 August 2019, is named "Universal Serial Bus 4" or "USB4". Several news reports before the release of that version sometime use
11500-574: The same technical notation retroactively added in the USB 3.1 and USB 3.2 specification versions. Though this shows common principles and the same generations refer to the same nominal speeds, "Gen A" does not have the same exact meaning in both USB 3.x and USB4 specifications. The overlap in naming mainly becomes relevant for cables as shown in Cable Compatibility , which is regulated by the Type-C specification shared across all users of Type-C connector. 11b/7t Thunderbolt 3 Gen 2 and Gen 3 and
11615-473: The specification of version 3.0 had been completed and had made the transition to the USB Implementers Forum (USB-IF), the managing body of USB specifications. This move effectively opened the specification to hardware developers for implementation in future products. The first USB 3.0 consumer products were announced and shipped by Buffalo Technology in November 2009, while the first certified USB 3.0 consumer products were announced on 5 January 2010, at
11730-431: The specification, and by the initials SS . USB 3.1 , released in July 2013, is the successor specification that fully replaces the USB 3.0 specification. USB 3.1 preserves the existing SuperSpeed USB architecture and protocol with its operation mode (8b/10b symbols, 5 Gbps), giving it the label USB 3.1 Gen 1 . USB 3.1 introduced an Enhanced SuperSpeed System – while preserving and incorporating
11845-483: The standard at Intel; the first integrated circuits supporting USB were produced by Intel in 1995. Released in January 1996, USB 1.0 specified signaling rates of 1.5 Mbit/s ( Low Bandwidth or Low Speed ) and 12 Mbit/s ( Full Speed ). It did not allow for extension cables, due to timing and power limitations. Few USB devices made it to the market until USB 1.1 was released in August 1998. USB 1.1
11960-552: The start, referenced the PCI Express Specification Revision 4 and with USB4 Version 2.0 added references to PCI Express Specification Revision 5.0 . PCIe tunneling has had a significant limitation in USB4 Version 1.0 and also Thunderbolt 3: PCIe Express has a variable maximum payload size , which applies end-to-end to a transmission. If any one component or PCIe Switch has a limited MPS , all packets passing through must be limited accordingly. Because USB4 uses
12075-477: The syntax "USB x Gbps", where x is the speed of transfer in Gbit/s. Overview of the updated names and logos can be seen in the adjacent table. The operation modes USB 3.2 Gen 2×2 and USB4 Gen 2×2 – or: USB 3.2 Gen 2×1 and USB4 Gen 2×1 – are not interchangeable or compatible; all participating controllers must operate with the same mode. This version incorporates
12190-415: The thinner Micro-USB connectors (Micro-A, Micro-B, Micro-AB). The Type-C connector, also known as USB-C, is not exclusive to USB, is the only current standard for USB, is required for USB4, and is required by other standards, including modern DisplayPort and Thunderbolt. It is reversible and can support various functionalities and protocols, including USB; some are mandatory, and many are optional, depending on
12305-489: The three existing operation modes. Its efficiency is dependent on a number of factors including physical symbol encoding and link-level overhead. At a 5 Gbit/s signaling rate with 8b/10b encoding , each byte needs 10 bits to transmit, so the raw throughput is 500 MB/s. When flow control, packet framing and protocol overhead are considered, it is realistic for about two thirds of the raw throughput, or 330 MB/s to transmit to an application. SuperSpeed's architecture
12420-468: The type of hardware: host, peripheral device, or hub. USB specifications provide backward compatibility, usually resulting in decreased signaling rates, maximal power offered, and other capabilities. The USB 1.1 specification replaces USB 1.0. The USB 2.0 specification is backward-compatible with USB 1.0/1.1. The USB 3.2 specification replaces USB 3.1 (and USB 3.0) while including the USB 2.0 specification. USB4 "functionally replaces" USB 3.2 while retaining
12535-405: The wrong terminology "USB 4.0" and "USB 4". Goals stated in the USB4 specification are increasing bandwidth, helping to converge the USB-C connector ecosystem, and "minimize end-user confusion". Some of the key areas to achieve this are using a single USB-C connector type, while retaining compatibility with existing USB and Thunderbolt products. On 18 October 2022 the USB Promoter Group released
12650-621: Was cancelled before production. Commercial controllers were expected to enter into volume production in the first quarter of 2010. On 14 September 2009, Freecom announced a USB 3.0 external hard drive. On 4 January 2010, Seagate announced a small portable HDD bundled with an additional USB 3.0 ExpressCard , targeted for laptops (or desktops with ExpressCard slot addition) at the CES in Las Vegas Nevada. The Linux kernel mainline contains support for USB 3.0 since version 2.6.31, which
12765-418: Was released in November 2008. The USB 3.0 specification defined a new architecture and protocol, named SuperSpeed, which included a new lane for providing full-duplex data transfers that physically required five additional wires and pins, while also adding a new signal coding scheme (8b/10b symbols, 5 Gbps; also known later as Gen 1), and preserving the USB 2.0 architecture and protocols and therefore keeping
12880-553: Was released in September 2009. FreeBSD supports USB 3.0 since version 8.2, which was released in February 2011. Windows 8 was the first Microsoft operating system to offer built in support for USB 3.0. In Windows 7 support was not included with the initial release of the operating system. However, drivers that enable support for Windows 7 are available through websites of hardware manufacturers. Intel released its first chipset with integrated USB 3.0 ports in 2012 with
12995-524: Was released on 1 September 2022 by the USB Implementers Forum. USB4 is based on the Thunderbolt 3 protocol. It supports 40 Gbit/s throughput, is compatible with Thunderbolt 3, and backward compatible with USB 3.2 and USB 2.0. The architecture defines a method to share a single high-speed link with multiple end device types dynamically that best serves the transfer of data by type and application. During CES 2020 , USB-IF and Intel stated their intention to allow USB4 products that support all
13110-419: Was released on 31 July 2013, replacing the USB 3.0 standard. The USB 3.1 specification takes over the existing USB 3.0's SuperSpeed USB transfer rate, now referred to as USB 3.1 Gen 1 , and introduces a faster transfer rate called SuperSpeed USB 10 Gbps , corresponding to operation mode USB 3.1 Gen 2 , putting it on par with a single first-generation Thunderbolt channel. The new mode's logo features
13225-434: Was the earliest revision that was widely adopted and led to what Microsoft designated the " Legacy-free PC ". Neither USB 1.0 nor 1.1 specified a design for any connector smaller than the standard type A or type B. Though many designs for a miniaturized type B connector appeared on many peripherals, conformity to the USB 1. x standard was hampered by treating peripherals that had miniature connectors as though they had
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