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📱 | Smartphones are hard to connect!Maybe it's because of the USB cable?


It's hard to connect to your smartphone!Maybe it's because of the USB cable?

If you write the contents roughly
Therefore, most smartphones have a component (common mode filter) that reduces common mode noise at an appropriate position, but if you do not connect a USB cable in the first place, the noise generation factor should be reduced.

Mobile lines are the lifeline of smartphones.If the reception sensitivity is low, the communication speed will decrease, and in some cases the communication will be interrupted ... → Continue reading


It is a site "PHILE WEB" (file web) that delivers daily news, reviews, bargain information, etc. on AV / audio / gadgets. First published in 1999.

Wikipedia related words

If there is no explanation, there is no corresponding item on Wikipedia.

Universal serial bus

Universal serial bus(British: Universal Serial Bus, Abbreviation:USB, USB)ComputerFor information equipment such as(I.e.For connectingSerial busOne of the standards.As the name of universal (general purpose) indicates,hostFor connecting various peripherals to the devicePeripheral busspecificationAnd the first standard, USB 1.0,1996/Appeared in. CurrentPersonal computerThe most popular general purpose peripheral deviceinterfaceIt is a standard.

According to the USB standard, up to 1 peripheral devices can be connected to one bus. If there are not enough connections, it can be expanded like a tree.USB hubIs also assumed to be used.Plug and playIt is also compatible with, which was not possible with a general external interface at the time of standard establishment.Hot swapWas also possible.

Host bus adapterFrom to peripherals电源It regulates the supply (bus power). Therefore, not only conventional computer peripherals, but also office supplies andMobile phone,Digital audio playerVariousmachineIt has also come to be used for supplying electric power to. There is also a charging cable that has a USB connector but does not perform any data communication specialized for this power supply function.

USB is a standard for connecting host devices and peripheral devices, and for direct connection between hosts and peripheral devices.USB On-The-GoIt is not compatible except for compatible devices, and although it lacks flexibility and limitations such as low power supply capacity, it is highly convenient in the current personal computer environment and is the most used standard for connecting to peripheral devices. .. Especially outsideStorage deviceOf USB connection that can be handled asUSB memoryIs often used because of its high portability.

USB 3.1 Gen 2 and above has a maximum transfer rate of 10 Gbps, USB 3.2 Gen 2x2 and above has a maximum transfer rate of 20 Gbps, and USB4 Gen 3x2 and above has a maximum transfer rate of 40 Gbps.


TraditionalRS-232CSerial port,IEEE 1284Parallel port,PS/2 connectorReplacement (later)Legacy port(It will also be called)Compaq,Digital Equipment Corporation (DEC),IBM,Intel,Microsoft,NEC,Nortel Networks7 companies jointly developed in 1994,Windows 98It became popular because it was officially supported in.

Furthermore, with the advent of USB 2.0 / 3.0, the transfer speed has been greatly improved, and conventionallyIDE,SCSI,EthernetI needed a high-speed transfer standardHard disk driveIt is also used for connection with devices such as.

USB 3 was messed up with minor versions, causing confusion for users. USB Promoter GroupのCEO、Brad SaundersはUSB 3における混乱を受けて、USB4を元にした新規格が作られた際には、マイナーバージョンではなく新名称を与える方針を公表したBrad Saunders, CEO of USB Promoter Group, announced a policy to give a new name instead of a minor version when a new standard based on USB XNUMX is created in response to the confusion in USB XNUMX.[1].

Standard owner

at firstIntel,Microsoft,Compaq(Current:Hewlett Packard),Digital Equipment Corporation(Currently: Hewlett-Packard),IBM,NEC, Northern Telecom (now:Nokia) Formulated the specifications,2017/As of SeptemberNPOThe "USB Implementers Forum, Inc." (USB-IF) is responsible for the formulation and management of specifications. USB-IF isApple, Hewlett-Packard, Intel, Microsoft,Renesas Electronics,ST Microelectronics6 companies are the leading companies, consisting of a total of 996 companies.

For the purpose of preventing random production of similar proprietary standardsPatentAlthough it exists, the patent royalties are free.In manufacturing USB devices, it is necessary to apply for a vendor ID to identify the manufacturer.

Many other bus standards require separate contracts due to patent payments, etc.Small businessAlthough it was difficult to enter the market, it is said that the USB standard promoted the spread that virtually anyone can enter as long as the rules are followed.toyA wide range of equipment is on sale.

Each generation of USB

The USB standard has been expanded several times in order to improve the maximum transfer speed. These are from 1.1 to 4Upward compatibilityTherefore, except that the functions and performances are bound by the lower standard, it is required to operate correctly even if the lower standard product and the higher standard product are connected.

USB comparison
Standard name (old name)Specification issue dateMaximum data transfer rate (effective speed)Maximum transmission distancePower supply capacity (5V)Remarks
USB 1.0March 1996Half double12 Mbps (1.5 MB / s)
  • 5 m
  • USB Type-C up to 4 m
  • 500 mA
  • USB Type-C for USB Power Delivery is 1.5 A or 3 A
USB 1.1March 1998
USB 2.0March 2000Half-duplex 480 Mbps (60 MB / s)
  • USB 3.2 Gen 1
  • (USB 3.1 Gen 1)
  • (USB 3.0)
March 2008Full double5 Gbps (500 MB / s)
  • 3 m
  • USB Type-C up to 2 m[2]
  • 900 mA
  • USB Type-C for USB Power Delivery is 1.5 A or 3 A
SuperSpeed ​​USB
  • USB 3.2 Gen 2
  • (USB 3.1 Gen 2)
March 2013Full dual 10 Gbps (1.21 GB / s)1 m[2]
  • 1000 mA
  • USB Type-C for USB Power Delivery is 1.5 A or 3 A
SuperSpeed ​​USB 10Gbps
USB 3.2 Gen 2x22017/9/25Full dual 20 Gbps (2.42 GB / s)
  • 1000 mA
  • 1.5 A or 3 A for USB Power Delivery
  • SuperSpeed ​​USB 20Gbps
  • Only compatible with USB Type-C
  • USB4
  • Full dual 20 Gbps (2.42 GB / s)
  • Full dual 40 Gbps (4.85 GB / s)
0.8 m[2]
  • USB4 ™ 20Gbps
  • USB4 ™ 40Gbps
  • Based on Thunderbolt 3

USB 1.0

1996/Announced in January. Up to 1 Mbps (1.5MB / s).

USB 1.1

1998/Announced in September. The USB 9 standard specifications have been improved for power management, etc. Up to 1.0 Mbps (1.5MB / s).

USB 2.0

2000/Announced in April. High-Speed ​​mode (up to 4 Mbps) has been added to the USB 1.1 standard specifications.

In some cases, 480 Mbps High-Speed ​​transfer and devices that support it are used interchangeably with the standard version number USB 2.0, but this is a misuse. Under the USB 2.0 standard, Full-Speed ​​and Low-Speed ​​devices can still be designed, manufactured, sold and used. USB-IF teaches to use "Hi-Speed ​​USB" as a term when it is desired to clearly indicate that it is High-Speed.[3].

USB 3.0

Standardization is being promoted by USB-IF,2008/Revision 8 was fourth in 1.0 at the Intel Developer Forum in AugustquarterIt is stated that it will appear in, and at the same time with the specifications of the pinConnectorandCable OfprototypeWas open to attendees. After that, the official name was changed to "Super Speed ​​USB".logoWas also released. In September 2008, the provisional standard revision 9 was decided.

The official specifications were announced at the "Super Speed ​​USB Developers Conference" on November 2008, 11, and the USB 17 standard became official as revision 3.0.

USB 3.0 is physicalBackward compatibilityThe maximum data transfer rate is 5 Gbps (however, since 8-bit data is converted to a 10-bit signal and sent, the actual data transfer rate is limited to 4 Gbps = 500 MB / s). .. The standard number of pins has increased by 5 to 9USB On-The-GoThere are a total of 10 compatible options, but the pin shape has been devised to ensure physical backward compatibility with the (standard) A terminal, (standard) B terminal, and micro B terminal compatible with USB 1.1 and USB 2.0. However, mini USB has disappeared from the standard.

The reason for the increased number of pins is that USB 2.0 and earlier and USB 3.0 and later use completely different signal lines.In other words, USB 3.0 or later works with a different technology than USB 2.0 or earlier.[4].

For NRZI whose encoding method is USB 2.08b / 10bAnd PRBS are adopted, and the communication mode is changed from half-duplex to full-duplex (two sets of simplex).Physical layerToPCI Express 2.0 technology is applied mutatis mutandis[5].Mobile deviceThere is a strong demand for reduction of power consumption due to consideration forPollingHas been eliminated and four new standby modes have been added.

In addition, it is recommended to use blue for the insulator part of the connector of the USB 3.0 compatible device to distinguish it from 1.1 / 2.0.

Electromagnetic radiationTo reduce the peak of noiseSpread spectrumThe clock was made mandatory. Although it was planned to include optical transmission, there were many oppositions from the cost aspect, and the introduction in revision 1.0 was postponed. Intel, which is aggressive in introducing optical transmission technology, is envisioning future adoption.

To prevent radiated electromagnetic noise, the signal cableshieldHowever, the prototype that meets the standard transmission distance of 3 m has a diameter of 6 mm, and depending on the mobile device, it floats in the air with a USB cable. In order to avoid such a situation, it is being considered to shorten the transmission distance to about 1 m and use a thinner signal cable with a standard within the range where transmission loss is allowed.

USB 3.0ChipsetBy being built intoMotherboardIncluded in the standard features ofAMDThe company is from A75, and Intel is from Intel 7 series.

When using an expansion interface card, it is necessary to pay attention to the communication speed bottleneck. The maximum transfer rate per port of USB 3.0 is 1 Gbps, and the maximum transfer rate of PCI Express x5 (Gen 1) is also 2 Gbps, so if you add a PCI Express x5 interface card that is widely available on the market , If you connect two or more USB 1 ports and use it, the transfer speed of PCI Express x3.0 becomes a bottleneck. To avoid this, interface cards that connect with PCI Express x2 slot have also appeared.[6]..In addition, the maximum power supply from the PCI Express x1 motherboard is 10 W, but if the power of the upper limit of the standard is supplied to the two ports of USB 3.0, it will be 2 W, which is insufficient when combined with the power consumption of the card itself.For this reason, many PCI Express x9 interface cards have an auxiliary power supply that connects the power lines from the power supply unit.

The reason why many PCs up to 2012 have a combination of USB 3.0 with 1 port (or 2 ports) and the rest with USB 2.0 ports is (1) USB 2009 controller can be supplied to the market as of 3.0. Renesas' USB 3.0 controller, which was the only manufacturer, technically supports only up to 2 ports, (2) USB 3.0 requires more power than USB 2.0, and requires a large capacity power supply. In case of (3) built-in chipsetCPU⇔South BridgeThe reason is that it is technically impossible to convert all ports to USB 3.0 at present because the bus bandwidth between them is not sufficient at present. SoonVIAManufacturers such as, etc. also support USB 3.0, and controllers that support 4 ports have also been developed, and around 5, five years after its appearance, laptop computers with few ports will be fully compatible with USB 2014. It was.

USB 3.1

On August 2013, 8, the USB 1 Promoter Group announced the completion of the development of the USB 3.0 standard. USB 3.1 incorporates USB 3.1 as follows (Gen means Generation).

  • USB 3.1 Gen 1 (05 Gbps) ← Conventional USB 3.0
  • USB 3.1 Gen 2 (10 Gbps) ← New expansion with USB 3.1

USB 3.1 Gen 2 mode enables 10 Gbps transfer with SuperSpeed ​​Plus USB[7].

SuperSpeedPlus USB 10 Gbps increases signal transfer speed from 5 GHz to 10 GHz and also data encoding8b / 10bMore efficient from128b / 132b By changing the physical layer such as the adoption of, the effective data throughput performance that is twice that of the current SuperSpeed ​​USB is realized. On the other hand, the logical layers such as software hierarchy and device protocol are common to the current USB 2, and in USB 3.0 Gen 3.1 mode it can be used in the same way as USB 1 at 5 Gbps, and both Gen 3.0 mode and Gen 1 mode are USB 2 hubs. -Compatibility with device cables is maintained (however, devices under the USB 3.0 hub will transfer at 3.0 Gbps).

As a result, USB 3.1 compatible devices are USB 1.1 / 2.0 logical layer + USB 1.1 / 2.0 physical layer, USB 3.x logical layer + USB 3.0 physical layer, USB 3.x logical layer + USB 3.1 physical layer 3 It is a complicated one that requires the internal operation of the pattern.

USB 3.2

July 2017, 7, USB 25 Promoter Group announces USB 3.0 standard[8].. Officially released on September 2017, 9[9].

USB 3.2 incorporates USB 3.0 and 3.1 as follows (Gen means Generation)[10].

  • USB 3.2 Gen 1x1 (05 Gbps) ← Conventional USB 3.0, USB 3.1 Gen 1
  • USB 3.2 Gen 1x2 (10 Gbps) ← New expansion with USB 3.2 (2 lanes)
  • USB 3.2 Gen 2x1 (10 Gbps) ← Conventional USB 3.1 Gen 2
  • USB 3.2 Gen 2x2 (20 Gbps) ← New expansion with USB 3.2 (2 lanes)

x2Represents 2 lanes. Two lanes are available only when a USB 3.2 compatible cable with Type-C connectors on both ends is used, and it is compatible with 2 Gbps[11].

Gen 2x2 isn't very practical because there's little reasonable reason to keep transfer rates at 10 Gbps while supporting two-lane operations that require twice the physical layer.[12][13].

You can also use a Standard-A and Type-C USB 3.1 Gen 2 compatible cable on one side, but you can't use two lanes.


Formulation policy announced on March 2019, 3[14].. Officially released on September 2019, 9[15]..Technically, the specifications will be released free of charge in 2018Thunderbolt 3 is the foundation, and it has upward compatibility with all the USB series so far and Thunderbolt 3[16].. Versions no longer have numbers after the decimal point, and there is no space between the numbers and the USB.

It is premised on using a Type-C connector with 2-lane operation, and the bandwidth is 20 Gbps as standard and 40 Gbps as an option.However, the data transfer protocol as USB remains USB 20 at up to 3.2 Gbps.Supported protocols (USB 3.2,DisplayPort, OptionalPCI Express)TunnelingAnd occupy at least one laneDisplayPort You can use USB 3.2 20 Gbps data transfer and DisplayPort video output at the same time with a single cable, which was not possible in Alt Mode.In addition, since the host side is obliged to implement video output by DisplayPort (USB4 and conventional DP Alt Mode), any port that conforms to the standard and claims to be USB4 will always support video output.

The total bandwidth of the connector is 20 Gbps as standard, and 40 Gbps if all host device cables support it.

  • USB4 Gen 2x2 (20 Gbps)
  • USB4 Gen 3x2 (40 Gbps)

Wireless USB

Wireless USBIt is,2005/It was announced in May.Wireless communicationSupports device connection by. Agere Systems (currently:LSI Corporation), HP, Intel, Microsoft, NEC,Phillips,Samsung electronicsIt was formulated by 7 companies. It considers the wired USB standard and connectivity, but is created as a standard independent of them.

Function outline

With USB, up to 1 devices can be connected to one bus and used at the same time. It also supports hot plugs. HoweverOS, Depending on the USB device, a warning may appear if you do not perform the procedure to stop the USB device when removing it. This is because the processing of the driver software may cause a problem due to the inconsistency of the state.

Host-based, depending on hub and deviceTree structureIt takes the connection form of.communicationData ispacketIt is converted and sent.HubAnd the device each has an independent bus address during operation. This address is dynamically assigned by the host when the device connects to the bus. The address is 7bitExcluding the special purpose address 0, 127 individual devices can exist on the same bus at the same time. Packets up to High-speedbroadcastThen, the device receives the necessary packet by looking at the destination address specified in the packet. After Super Speed, it is unicast. Since communication needs to be started by the action from the host side, unlike SCSI etc., communication cannot be started from the device side on the bus basically. Extended specifications for connecting peripheral devices directlyUSB On-The-GoIn, it is designed to have a "host-to-device" relationship by acting as a host on either side.

transfer speed

Low-Speed ​​(LS mode)-1.5 Mbps
Used for peripheral devices that do not require high-speed communication, such as keyboards and mice.
Full-Speed ​​(FS mode) -12 Mbps
Image scanner,printerUsed for peripheral devices that require communication speed. This speed is maximum up to USB 1.1. G5 Laser Mouse, etc.LogitechIt is also used in some mice.
High-Speed ​​(HS mode)-480 Mbps
It can handle large-capacity storage at a practical speed. Newly established with USB 2.0.
SuperSpeed ​​(SS mode) -5 Gbps
It can handle high-speed devices such as SSD (Solid State Drive). Newly established with USB 3.0. It is called Gen 3.1 in the USB 1 specification and Gen 3.2x1 in the USB 1 specification.
SuperSpeedPlus (SS + mode) -10 Gbps, 20 Gbps
It can handle high-speed devices such as SSDs of 600 MB / s or more. New with USB 3.1, Gen 2 is 10 Gbps. With USB 3.2, 2 lanes can be used, and there are 2 types, Gen 1x2 and Gen 2x3, and Gen 2x2 is 20 Gbps.Gen 1x2 also exists in the standard, but it is not practical (it is more rational to use Gen 10x2 for 1 Gbps and Gen 2x2 for 2 lanes), so there are few products.[13][12].

Unique speed-up technology

When HDD etc. are connected, the transfer speed is high even in High-Speed ​​mode with Mass Storage class compliancebottleneckTherefore, some products are shipping products that improve the effective speed by devising the transfer method.BuffaloWith "Turbo USB"IO data equipment"Mach USB" claims that it will be 20-30% faster.softwareIt depends on the performance of the connected PC because it is processed by, and both companies support only Windows and Mac OS.

Transfer mode

Control transfer
For device setting and control.
Interrupt forwarding
For transferring data at regular intervals. Used for keyboards and mice. Unlike what the name suggests, it is achieved by polling at regular intervals from the host.
Bulk transfer
For transferring a relatively large amount of data aperiodically.Auxiliary storage,Image scannerUsed for etc.
Isochronous transfer
Transfer data continuously and periodically. Certainty is not guaranteed because there is no retransmission.video,Audio equipmentIt is used for input / output of.

USB Attached SCSI Protocol

USB Attached SCSI Protocol (abbreviation: UASP) is an extended specification of USB and is one of the communication protocols.

Generally, bulk transfer is used for communication with the auxiliary storage device, and the communication speed is lowered due to poor transfer efficiency. Instead, the communication speed can be improved by applying the communication protocol used in SCSI devices.

In order to use UASP, it is necessary to support personal computers and devices and the OS that controls them.

Device class

In USB, grouped by peripheral functionDevice classA group of specifications called is defined. A unified control interface is prepared for devices created according to each class specification (subclass specification depending on the class specification), and devices that comply with the class specification are available.Class driverCommon calledDevice driver-Since it can be operated by software, it is not necessary to create individual driver software for each product if it is in the same class. For example, manyUSB memory TheMass storage classIf the OS side prepares a class driver compatible with the mass storage class, a new driver will be added as long as the USB memory complies with the class specifications.InstallYou don't have to do it, and it works immediately when you connect for the first time. However, in reality, due to specification violations on the device side, device implementation that depends on the operation of a specific host, blurring due to ambiguity in the specifications, etc., bug avoidance processing is included in the driver that does not work with a common class driver. , A dedicated driver may be provided.

As of November 2009, the device classes defined by USB.org are:[17].

Class IDDescriptor to usename of the classUse
00hDevice(undefined)[18](Indicates that the device class is undefined. In this case, the interface descriptor identifies the driver to use.)
01 hInterfaceaudiospeaker,Microphone,Sound card,MIDImachine
02 hBothUSB communications device class (Communications and CDC Control)Ethernet card,modem
03 hInterfaceUSB human interface device class (Human Interface Device (HID))Keyboard,mouse,Joystick
05 hPhysical Interface Device (PID)Force feedback joystick
06 himageWebcam,Image scanner
07 hprinterprinter,CNC CNC
08 hUSB mass-storage device classUSB memory,Memory card reader/writer,Digital audio player,Digital still camera,External storage
09 hDeviceUSB hubUSB hub
0AhInterfaceCDC-Data(Used at the same time as Communications and CDC Control with class code 02h.)
0BhSmart CardUSB Prepaid Cardleader
0DhContent securityfingerprintReader
0EhUSB video device classWebcam
0FhPersonal HealthcareHeart rate monitor (clock with heart rate monitor)
DChBothDiagnostic DeviceUSB compliance test device
E0hInterfacewireless ControllerWi-Fiadapter,Bluetoothadapter
EFhBothMiscellaneousMicrosoft Activesync device
FEhInterfaceApplication definitionIrDABridge, Test & Measurement Class (USBTMC)[19], USB DFU (Direct Firmware update)[20]
FFhBothVendor definition(Indicates that a vendor-defined driver is used.)

Host controller type

In the USB standardHost controllerThe following host controller standards are outside the USB specifications. There are multiple host controller standards. Since these have different control methods, different drivers are required for each. However, common ones can usually be used within the same host controller standard.

UHCI (Universal Host Controller Interface)
Developed by Intel and used in Intel and VIA's x86 chipsets. Developed in the USB 1.x era, it supports Full / Low Speed.
OHCI (Open Host Controller Interface)
Microsoft, Inc.National SemiconductorDeveloped by Compaq and Compaq, and used in chipsets other than Intel VIA. Developed in the USB 1.x era, it supports Full / Low Speed.
EHCI (Enhanced Host Controller Interface)
Developed by Intel. However, as a contributorCompaqCompany,Lucent TechnologyCompany, Microsoft, and NEC are listed. Supports High Speed ​​newly established in the USB 2.0 standard. Usually the same "Companion Host Controller" (UHCI, OHCI is normal) for communicating with Full / Low Speed ​​devicesチップImplemented inside, responsible for communication when Full / Low Speed ​​devices are directly connected without going through a hub. EHCI can also communicate with Full / Low Speed ​​devices, but in that case it is executed after the communication speed is converted to High Speed ​​by the USB 2.0 standard hub between the devices.
xHCI (eXtensible Host Controller Interface)
Developed by Intel. Supports SuperSpeed, which was newly established in the USB 3.0 standard. It has already been provided by Intel, and the development of peripheral devices has begun.
WHCI (Wireless Host Controller Interface)
A Wireless USB host standard developed by Intel. It defines UWB general control, Wireless USB host section, and multiple functions at the same time. The control method of the Wireless USB part is similar to EHCI.
ScanLogic's SL811HST, NXP Semiconductors' ISP1160, etc.
A USB host controller directly connected to the microcomputer bus for embedded applications. Since it is not standardized, it is not compatible at all if the manufacturer is different.

Physical connection

Terminals / connectors

The shape of terminals / connectors is defined by the same standard as the transfer protocol up to USB 2.0, and by a standard independent of the transfer protocol after 3.0.Mini A terminal B terminal and AB socket are extended standardsUSB On-The-GoIt is defined in the standard. The defined terminal shapes are as follows.

  • Compatible products up to USB 2.0
    • USB A plug and socket (Standard-A)
    • USB B plug and socket (Standard-B)
    • Mini USB specifications
      • Mini A plug and socket
      • Mini B plug and socket
      • Mini AB socket
    • Micro USB specifications
      • Micro A plug and socket
      • Micro B plug and socket
      • Micro AB socket
  • Compatible products up to USB 3.0
    • USB A plug and socket (Standard-A)
    • USB B plug and socket (Standard-B)
    • Micro B plug and socket
  • Compatible products up to USB 3.1
    • USB A plug and socket (Standard-A)
    • USB C plug and socket

The A terminals are used for the computer body and hub (downstream / device connection side), and the B terminals are used for peripheral devices and hubs (upstream / host connection side). Mini B terminals areDigital cameraUsed for small devices such as. By changing the terminal shape, the connection method is restricted so that the wooden structure of the bus topology can be maintained.

The mini AB socket (female side connector) can be connected with either the mini A plug or the mini B plug, and the same applies to the micro AB socket (female side connector). For more informationUSB On-The-GoSee.Mobile information terminal,SmartphoneIt is used in some parts such as. These on-board machines operate as "slave units" when connected to a personal computer, and when used alone, they are assumed to be used as "master units" by connecting other USB equipment, and are adopted for miniaturization. doing. At the time of use, it is judged which operation should be performed by exchanging the connection cable. The main unit also has a built-in USB host function.

Terminals and sockets that can support up to USB 3.0 have been newly added to the specifications since November 2008. As before, the upward compatibility with USB 11 or later is maintained, and the terminals and sockets that can support up to USB 1.1 can be mixed with those with USB 3.0 or later. In response to the increase in the number of pins in USB 1.1, the new terminals and sockets meet the standard shape up to USB 3.0, but are in a recessed position (A), two-tiered (B), and horizontal position (side-by-side called SideCar). The arrangement of, Micro-B) has been increased with additional terminals. (By the amount of this increased terminal, the USB 2.0 B connector and Micro-B connector are larger than the B connector and Micro-B connector up to USB 2, and connect the connection cable for USB 3.0 to the USB 2.0 device. Can't.)

In all generations, the terminals are longer at the power supply terminal than at the data terminal. This is to prevent the data terminal from being damaged by applying a voltage to the data terminal when the device is inserted or removed without the power being turned on.

Supplement:WACOMThe LCD tablet PL-550 that was released byMini DIN connectorUses a 4-pin connector. But the pin assignment isS terminalTomo ADB (Apple Desktop Bus) Is also different. Currently, it is difficult to obtain this cable alone in Japan.


BYR color wheel.svgIn this itemColorWe are dealing with.Colors may not be displayed properly depending on the viewing environment. ((Template: Color)
Normal USB color coding
カ ラ ーportplugDescription
Black or white○Type-A or Type-B
blueType-A or Type-B, SuperSpeed ​​(3.x system)
Teal blueType-A or Type-B, SuperSpeed ​​+ (3.x system)
グ リ ー ンType-A, or Type-B, Qualcomm Quick Charge[21]
purpleー○Type-A, or USB-C, Huawei SuperCharge
Yellow or red○ーHigh current or sleep & charge
OrangeHigh retention connector mainly used in industrial hardware.

USB ports and connectors are often color-coded to distinguish between different features and the USB version.However, these colors are not part of the USB specification and may vary from manufacturer to manufacturer.For example, the USB 3.0 specification requires proper color coding, but standard A USB 3.0 connectors and plugs are blue (Pantone Only 300C) inserts are recommended[22].

USB Type-C

Established by the USB 2014 Promoter Group in August 8[23]..It features a reduced size for small devices such as smartphones, support for USB Power Delivery that enables power supply up to 100W, and a structure that can be inserted either front or back.However, please note that even devices equipped with a USB Type-C connector do not always support USB 3.1 or USB Power Delivery (connector shape and function must be considered separately).

The features are as follows.

  • There is no front and back[24].
  • Data transfer, video transfer, power supply are possible[24].
  • Compatible with old standard USB 2.0 and future standards[24].
  • Supports protocols other than USB, such as HDMI and VirtualLink

Pin placement

Pin placement
Standard USB connectorMini / micro USB connector
PinFunction (host side)Function (device side)PinFunction (host side)Function (device side)
1VBUS (4.75 --5.25 V)VBUS (4.4 --5.25 V)1VBUS (4.75 --5.25 V)VBUS (4.4 --5.25 V)

Terminal shape / direction

When you look at the USB A terminal from the front, it is just a rectangle from either side, and you may make a mistake on the front and back for connecting. Actually, it is possible to judge by the USB mark on the surface of the male side (the side with the hole), but the user may try to reverse it without being aware of it. By covering about half the thickness of the USB port and the male connector with a plastic plate, reverse insertion is physically impossible (see each photo in this article), so insert the USB plug. There is no situation.

BuffaloReleased the original "Both USB" series (USB hub, cable, etc.) in 2012 that can be used normally by inserting either the front or back of the A terminal.[25][26].


In the USB 2.0 standardCableThere are two types, one for High / Full Speed ​​and the other for Low Speed. The electrical characteristics for Low Speed ​​are loose so that it can be manufactured at low cost. All single cables are for High / Full Speed, as Low Speed ​​devices are explicitly prohibited from being designed with separate cables.

Since the USB 3.0 standard has more signal lines for SuperSpeed, the cable for USB 3.0 is also used.

To prevent erroneous connection, the A terminal is specified as the host side and the B terminal is specified as the device side. For this reason, cables with A terminals on both sides or B terminals on both sides are non-standard products.

Apart from this, there is no problem with the USB extension cable with A terminal and A socket in terms of using A and B terminals properly, but there is a risk of exceeding the specified length due to multiple connections, so this is also a standard Explicitly prohibited[27].


Between versions

The USB 2.0 standard is designed to be compatible with the USB 1.1 standard, so you can use it by connecting a device designed with the USB 2.0 standard to a USB port of the USB 1.1 standard. In addition, even when a High Speed ​​device newly established with the USB 2.0 standard is connected to a port or hub designed with the USB 1.1 standard, it can be used at the full speed transfer speed. The USB 3.0 standard is also designed to be compatible with the USB 2.0 standard. However, there are products that claim USB 3.0, even though they do not comply with the current USB 3.0 standard. These may cause problems such as incompatibility with USB 2.0 and slow transfer speed.


USBCableThe standard hasn't changed in USB 2.0, so you can use the same one. Low-quality cables that do not properly comply with the USB 1.1 standard may be restricted by cable length in High Speed ​​communication. There is also a cable called "USB 2.0 compatible" on the market. This is from the outside such as shield wire structurenoiseIt is considered that some measures have been taken to prevent this.

It is often overlooked, but it should be noted that even if the AC adapter has sufficient power supply capacity, the power supply capacity will be limited if a cable that meets the standard is not used.

Host controller

When viewed from the device, there are subtle differences in communication timing between the host controllers.[Source required],So-calledCompatibilityIt is probable that there was a device in the past that did not operate normally unless it was either.


Manufacturer, model, of USB host controller and controller on the USB device side,firmwareIt is also known that compatibility problems have occurred due to differences such as, and problems on the OS and driver side, and in particular, there have been confusions when connecting controllers that appeared in the early stages of standardization. ..

Regarding this "early compatibility problem", Intel built a USB host controller in its own PC chipset so that each device is compatible with the host controller of the Intel chipset and the connection to Windows. Both USB 1.1 and 2.0 have traced the result that the compatibility problem between devices is indirectly converged by securing the above.

Also, with specifications up to USB 1.1,ImpedanceSince the specifications for electrical characteristics such as these were loose and the standard conformity test was not essential, there was also a situation in which the occurrence of compatibility problems could not be suppressed. From the USB 2.0 specifications, the electrical specifications have become stricter, and standard conformity tests to obtain the USB logo have become mandatory, so it is said that the "compatibility problem" has been almost eliminated.

However, there may be products that are manufactured in the early stages and have compatibility problems in the hands of the market and users, and compatibility problems occur between host controllers made by some manufacturers and vendors and controllers. The situation still exists.

Specific symptoms include the USB memory being recognized but the contents not being displayed (it works normally when connected to another connector), the portable music player connected in storage mode shuts down in the middle, etc. Can be mentioned.

Multiple device connection

According to the standard, up to 127 devices can be connected to one bus. The tier that indicates the "depth" of the tree structure is limited to 7 levels including the root hub (host). This means that there can be up to 5 hubs between the device and the host. The maximum cable length is defined by the standard as the maximum delay time and VBUS voltage drop, up to 1 ns and 26 mV per cable (§125, 7.1.16).

But in reality, USB controllers and hubs and USB devices "Compatibility, And is restricted by the number of physical ports provided by the hub, and except for cases such as connection tests by USB-related device developers, etc., 127 devices are actually connected and used on a daily basis. Examples are extremely rare. In other words, it is unlikely that the end user will saturate the number of logical connections in the standard within the range of general use, and it can be said that the standard has a margin.

Weekly ASCIIIn the experiment, errors occurred frequently from around the 80th unit, but it was said that up to 100 units could be put to practical use if the connection method was devised.[28].

USB power supply

USB power supply standard
USB 1.x and 2.0500 mA[Annotation 1]5 V2.5 W
USB 3.x900 mA[Annotation 2]4.5 W
USB Battery Charging
Revision 1.2
0.5 - 1.5 A.2.5 - 7.5 W
USB Type-C[Annotation 3]A 1.57.5 W
A 315 W
USB Power Delivery
Revision 1.0[Annotation 4]
A 210 W
A 1.512 V18 W
A 336 W
A 560 W
A 320 V
A 5100 W
USB Power Delivery Revision 3.0 Power Rules[29]
Power supply output power (W)Current (A)
+5 V+9 V+15 V+20 V
0.5 – 15 Feet0.1 – 3.0 FeetNoNoNo
15 – 27 Feet3.0
(15 W)
1.7 – 3.0 Feet
27 – 45 Feet3.0
(27 W)
1.8 – 3.0 Feet
45 – 60 Feet3.0
(45 W)
2.25 – 3.0 Feet
60 – 100 Feet3.0 – 5.0 Feet

USB is basically designed as a signal cable. On the other hand, in consideration of practical convenience, for low power devices, power is supplied to drive the connected peripheral devices with a USB cable.Bus poweredIt also supports driving by (often abbreviated as "bus power"). SupplyVoltageIs 5 V (± 10%),電流 TheLow power deviceIs 100 mA (USB 3.x is 150 mA),High power deviceUp to 500 mA (USB 2.0) / 900 mA (USB 3.0)[30]It is said that. The maximum current was up to 500 μA when the USB device was suspended, but with the 2007 release of the Link Power Management Addendum ECN it was up to 2.5 mA.[31].

USB Battery Charging Specification (USB BC)

It is a standard for USB power supply, and attempts are being made to extend the power supply specifications of the USB 2.0 standard. USB IF released Revision 2007 in 1.1 and Revision 2010 in 1.2[32].. The traditional USB 2.0 port is defined as the Standard Downstream Port (SDP)[33], Two new types called charging ports have been standardized.

Charging Downstream Port (CDP)
Supports data communication in addition to power supply up to 1.5 A. By performing a hardware handshake on the data line, it is possible to supply power up to 1.5 A even before enumeration (connection recognition). Up to 900 mA in high speed mode.
Dedicated Charging Port (DCP)
It only supports power supply up to 1.5 A and does not perform data communication. It is recognized as a DCP by short-circuiting the D + and D- pins of the terminal. No enumeration is performed.

USB Power Delivery (USB PD)

In July 2012, the USB 7 Promoter Group announced that it had completed the standardization of USB Power Delivery (USB PD) Revision 3.0 Version 1.0.[34].. Used in coexistence with USB Battery Charging Revision 1.2. 10 of 18 W, 36 W, 60 W, 100 W, 5 WPower profile There is (Power Profile), and it is possible to supply power up to 20 V, 100 W by using a certified PD compatible USB cable and USB A / B connector. Micro USB B / AB connector up to 20 V, 60 W. Power can be supplied from the host to the device and from the device to the host without reconnecting cables.

USB Power Delivery Revision 2014 Version 3.1 was released as part of USB 2.0 in 1.0USB Type-CCompatible with cables.

USB Power Delivery Revision 2016 Version 2.0 and USB Power Delivery Revision 1.2 Version 3.0 released in 1.0 replace the five power profiles.Power rules It became a power supply specification called (Power Rules). Backward compatible with USB Power Delivery Revision 2.0. There are voltage specifications of 5V, 9V, 15V, and 20V, and the supply side must support all voltages that are below the maximum supply power at 3A. Voltages and currents other than power rules are also allowed as options[35].. It officially became a power supply standard dedicated to USB Type-C, and PD with a USB A / B connector was removed from the standard without widespread use.

In USB Power Delivery Revision 3.0 Version 1.0, optionalProgrammable power supply It has a function of (Programmable Power Supply; PPS), the voltage can be changed, unnecessary heat generation during charging can be reduced, and power utilization efficiency can be improved.[36].. Used in some smartphones, etc.[37].

Also, with USB Power Delivery Revision 3.0 Version 1.0, it is optionalFast roll swap It has a function of (Fast Role Swap; FRS), and the roles of power supply and power reception can be switched within 0.15 milliseconds.[36].


USB power supply specifications are initially for low power devicesPC/AT compatibleInPS/2 connectorWith the replacement of the low power installed in the mouse and keyboard in mindsemiconductorlogicIt was designed on the premise of driving such as. In addition, although it is assumed that high power devices require more power than their logic circuits, all of themspindle(motor) Drive and equipmentChargingIt was not intended to use large amounts of electricity as a means. For this reason, when the supply current is suppressed, such as in a part of a small notebook computer, the operation of the USB connection equipment that is supposed to operate with a current close to 500 mA may be unstable or may not operate.

Requires more power than specified as a high power deviceDisk driveMotor-driven equipment such as, and large-scaleIntegrated circuitFor images that consume power, includingcaptureRegarding devices, it was decided that the USB bus would be used purely as a signal bus, and that power would be supplied by a connection means called "self-power" prepared by the device.

If you connect a large number of bus-powered devices or connect them in multiple stages using a bus-powered hub, the power supply capacity will be exceeded, so power will be supplied to the port side.shut downIt has a function to do. Inadvertently excessive on the user sideOctopus foot wiringMost of the commercially available bus-powered USB hubs are composed of 4 ports or less.

USB ports and bus-powered hubs do not support the connection of ports that consume significantly more power than the power supply capacity, and in the worst case, the hub or PC side.Interface cardProtective circuits such as buses, power circuits, etc. may be activated or damage the equipment.

Devices that consume more power

However, in fact, with the spread of USB, this small amount of power supply has been reduced to 2.5-inch and 1.8-inch portables on the market.Hard disk driveAlso, it consumes a lot of powerDVD-RIt can be used for power supply to spindle media such as writing drives, mobile phones, etc.PHSExamples of using it as a power source for charging batteries have begun to stand out.

With the connection cable to the computerACIn order to eliminate the hassle of preparing a separate power supply, the user's request to connect devices with a single cable is persistent, and in order to increase the power supply capacity of USBPlusPowerThe expansion of voltage and current was also considered. However, it was not officially included in the specifications due to a series of indications such as safety and compatibility issues.


To solve this problemPoweredUSBA standard that extends the USB 2.0 port has appeared from IBM[38][39].. Supply voltage 5 V / 12 V / 24 V. The maximum current is 6 A. A connection cable compatible with Powered USB is required. However, as of November 2012, the standard has not been officially approved by USB-IF.

In addition, there are peripheral devices that do not recognize the device and supply only power. A special bifurcated cable for supplying bus power for two units from two host connectors to one device is applicable.

Standard for charging mobile devices

Ministry of Information Industry, People's Republic of ChinaThen, in 2006, a USB port was provided on the mobile phone charger, and multipleCareersWe have set out a policy to allow the AC adapter to be shared between[40].

2007/In April, the standard "Battery Charging Revision 4" was established to shorten the charging time via USB.[41].. This is a standard of a mechanism that enables a charger or the like to obtain a current exceeding the upper limit of 2.0 mA in the conventional USB 500 standard by detecting whether a USB host can carry a large current. ..

In June 2009, mobile phone industry groups andEUHowever, there is a movement to adopt micro USB for the connector of the charger of mobile phone terminals and make it common.[42][43][44].

USB as a dedicated power supply port

On the market, from the USB port of a PC or self-powered hubOutletPeripheral devices that use USB only for power supply have gradually appeared by taking advantage of the fact that power can be obtained. Not just mobile deviceshandheld game console,Digital audio playerChargers and charging cables for mobile devices such asSmall fan,Electric lightPeripheral devices that are not recognized as devices such as these, and some that have almost no advantage in obtaining power from USB, have been commercialized, and are crowding the product shelves in the electric town. Desktop that appears at the end of the yearChristmas treeAnd summer fans are no longer availableTraditional poetryEven. Some people have made their own "roasted meat plate" that uses 30 USB bus powers (15 amps in parallel, 75 watts in total) as a power source.[45].

On the other hand, in the form of following the development of "USB as a power supply dedicated port" type peripheral device such as these, it has a connector with the same shape as the USB port, which is limited to the power supply function only to supply power.AC adapterAnd rechargeable batteriesDry cellPower supply units, etc. that use such devices are also on sale.By using such a product, it is possible to charge each device without having to carry an AC adapter when going out, and there is a convenience that a plurality of devices can be used with a single AC adapter.Also different from country to countryOutletShape andfrequency-Since the USB adapters sold in each country can handle the voltage, etc., instead of the device side, there is an advantage that the design of the export machine becomes easy as a manufacturer.USB outlets that are embedded in a wall outlet box to provide a USB port for power supply are also commercially available.

However, with the exception of some models guaranteed by the manufacturer, charging using these "USB port-related products dedicated to power supply" is not covered by the manufacturer's warranty.

Also, when connecting these "USB as a dedicated power supply port" type peripheral device to a USB port as a normal interface, most of them are not covered by the operation guarantee (in the first place, without the permission of the host side). An implementation where the target "takes power" on its own is a violation of the USB standard).

Recently, it has touted high-performance USB power supply capability.MotherboardIs also on sale.

USB power and security

Since the early 2010s, there have been an increasing number of cases where power is provided in cafes, hotels, airports, passenger planes, railroads, long-distance buses and taxis to facilitate the charging of users' smartphones and the use of laptop computers. ..

ManyCommercial power supplyHowever, since the plug shape and voltage of the commercial power supply differ depending on the country or region, we provide a USB power supply using a wall-mounted USB outlet in consideration of cases where overseas travelers cannot use their AC adapter. In some cases, the USB-AC adapter is rented out.

However, USB was originally established as a connection standard for data communication, and is not a standard that is supposed to be used exclusively for power supply. Even if the device / connector seems to be dedicated to power supply at first glance, data can be extracted from the device to which it is connected.Computer programIt is difficult to guarantee that you will not send.Some USB chargers are color-coded such as red, green, and yellow on the resin parts of the USB connector to clearly indicate that they are for charging only (blue means USB 3.x, not for power supply). ), But it is not a unified standard, and it is easy to use these colored connectors because fraudulent devices are disguised.

Therefore, it is possible to extract data from information devices.Computer virusFrom the standpoint of preventing infection, these USBs (micro USB and micro USB) can be used in facilities other than trusted locations such as homes, even if USB ports are provided for power supply.lightningFor information devices such as smartphones and tablet terminals, prepare a genuine adapter by yourself and use a commercial power outlet without using a cable that can communicate data or a rented USB-AC adapter. Can be charged fromComputer securityAbove desirable.

USB AC adapter

Since the 2010s, USB AC adapters have become widespread with the advent of smartphones and wireless headphones that support USB charging.

For smartphones, a USB AC adapter with a USB Type-A port has generally appeared, but after smartphones came to support the USB Type-C port, a USB AC adapter with a USB Type-C port also appeared. doing[46].. Since around 2019Gallium nitrideBy adopting technology, the size and weight have been reduced, and products equipped with multiple ports and capable of charging two or more devices at the same time have also appeared.[47].

When purchasing a USB AC adapter for use in Japan, specify electrical equipment.PSE mark, Select equipment with indications such as manufacturer's name, rated voltage, rated power consumption, etc.[48]..In addition, pay attention to whether the manufacturer (the company that sells the equipment with its own brand) can trust it, and whether it is a fake brand product, and do not use equipment that you do not remember purchasing or equipment whose source is unknown. Is desirable.

Poor contact with USB

USB has often been seen since the time of USB 1.0. Especially with USB 1.0, if it is used with the contact surface facing up on the male side of the device, it often causes poor contact due to dust and corrosive substances (salt). Further, the metal frame portion is deformed while the terminals are repeatedly attached and detached, and the contact pressure is lowered, which may cause poor contact.

In mobile devices such as smartphones, the terminals are often used not only for communication but also for power supply and charging, but if you put them in your pocket, dust may get into the terminals and cause poor contact. In addition, the metal frame may be deformed each time it is repeatedly attached and detached, and the pressure at the contact point may decrease, resulting in poor contact.

When poor contact occurs, not only power supply and charging become unstable, but also communication becomes unstable, which is serious for hard disks and USB memory, for example, and not only causes data errors, but also sometimes irreversible hardware. An error may occur.

First, when poor contact occurs, it is necessary to confirm whether the metal frame of the terminal is deformed. In many cases, the terminal frame is deformed and widened due to attachment and detachment, and the pressure of the contacts decreases. Therefore, it may be solved by manually narrowing the metal frame.

There is no appropriate solution other than blowing air for dust and corrosion of the contacts, but a method of polishing the contacts using a receipt has been reported.[49].. This is a method of polishing and removing dust and oxides from contacts with a layer of calcium carbonate applied to the receipt. It is simple and easy to obtain, and because it is non-conductive, there is no danger of short-circuiting contacts.


USB is a new general-purpose bus interface that replaces the legacy interface.Compaq(Current:Hewlett Packard) Intel, Microsoft,NECIt was formulated by.

From the beginning, USB has attracted attention as an epoch-making interface that enables hot plugging.Microsoft WindowsThen.Windows 95 From OSR2MacintoshTemporarily dedicated to the original iMacMac OS 8.1It came to be supported from. However, Windows 95 OSR2 and USB Supplemental Support, provided by the manufacturerDevice driverCorrespondence by the combination of is an additional specification, and peripheral device manufacturers are not enthusiastic and are included as standard specifications of the OSWindows 98There was a strong sense of wait-and-see until the appearance of. With the advent of the iMac in the Macintosh environment with the non-USB interface truncated, USB has spread rapidly, but up to Mac OS 8.6, which is standard support, it had a number of glitches and problems.

NEC, which was involved in the formulation of USB specifications, was the quickest mover in Japan than USB. NECPC-9821 series,PC98-NX seriesNot only is it equipped with a USB port, but in 1997Terminal adapter, Mouse, keyboard, scanner, printer,JoystickVarious kinds of USB devices such as were introduced. However, these quick deployments also caused confusion, with some being unsupported on Windows 98 and later.

PC/AT compatible

The first host adapter product was for PC in 1996PCIAppeared as a card to add to the interface.

Also Intel1996/Chipset for PC released in430HXWith the built-in USB host adapter function, PCs equipped with USB will rapidly become widespread.

At the beginning

IBMIt is,ApptivaJ / H series November 1996 modelOn boardIntroduced a model equipped with a USB port (due to the adoption of the 430HX chipset mentioned above). But the keyboard and mousePS/2 connectorWas connected to.

In Windows 95 OSR2 at that time, support for USB devices was limited, so we only attached an unofficial USB driver that IBM does not guarantee operation, and the manual attached to the model included this driver. The attached disk clearly states that the operation is not guaranteed, and even with the company's support dialPre-installedIt was announced that there is no guarantee of operation in the environment where it was operated with Windows 95 and the attached driver. These are not limited to Aptiva, but the same applies to other compatible machines of the same period. The USB ports of these models had the property of being officially supported for the first time when an OS with a USB support function such as Windows 98 was introduced.

In Japan, NEC has abolished the PS / 2 connector by connecting the standard mouse and keyboard via USB.1997/Released in the fallPC98-NX series(Semi-PC/AT compatible) Is the first. This is a USB-connected mouse and keyboard "legacyEmbroideryIt is made to operate as a PS / 2 device. However, for the early PC98-NX series, the PS / 2 connector exists on the motherboard, it remains only with no holes in the housing, and legacy ports such as serial / parallel are still alive, etc. Was not thorough. In addition, some models at that time had a problem with the default setting of the BIOS, and could not be recognized correctly when installing the Linux 2.4 series kernel at that time (the kernel side did not assume legacy emulation). Following this process, laterThird partySome of the USB devices released by each company disliked troubles and indicated that the operation was not guaranteed on the PC98-NX series.

USB 1.1

In addition, USB 1.1 was officially supported from Windows 98 Second Edition, and most USB devices that appeared after that did not include the initial version Windows 98 or earlier in the supported environment. However, the Second Edition does not come standard with many general-purpose drivers such as the USB mass storage class, so it is necessary to install the drivers individually, and it is not convenient to use immediately after inserting it.

Although the USB host adapter was quickly realized and installed in this way, the market centered on PC compatibles was not forced to make a rapid transition, and the transition to USB was gradual. Compatibility verified over the years, wellmaintenanceThe legacy interface has the advantage that both hardware and software (drivers) are "withered" and stable in operation, and the simple specifications reduce the load on the CPU. The parallel port also has a higher transfer rate by ECP than USB 1.1, and SCSI is even faster. Many of these legacy interfacesHot swapAlthough it does not correspond to the above, the support for plug and play has been completed, and since there was no particular inconvenience in terms of usability, there is also a situation that it is difficult to find a merit in migration in terms of convenience at the stage of USB 1.1. Was there.

Especially for keyboards, the number of key rollovers is limited to 6 according to the USB HID specifications (for further simultaneous pressing, it is necessary to assume that the previously pressed key was released. There is a demand for PS / 2-connected keyboards for games, etc. (Some keyboards have a USB connection that solves this problem with a special driver that is not a standard driver and a proprietary protocol).

USB 2.0 or later

USB 2.0 has appeared as a USB device in the PC market2000/It began to spread in earnest around that time, and now the mainstream of buses for connecting external peripheral devices has shifted to USB. Legacy-free PCs that do not have a legacy bus are also appearing, especiallyLaptop PCThen, it was not unusual from a relatively early stage. But the combination of USB and legacy ports has also been around for over a decade. PCs with legacy ports have also been on the market until very recently.the 2000sThe current situation is that the complete transition is finally being completed more than 10 years after the advent of USB.

In-Stat, a US research firm, reported that the number of USB ports shipped worldwide in 2007 reached 26 billion. The company has this number2012/Will have 43 billion ports, of which USB 3.0 is projected to be 4.5 million ports[50].


Equipped with USB as standard in 1998iMacIs a conventional general-purpose interface with a novel design integrated with a monitor.ADBAs wellSCSI,RS-422The serial port was also abolished and integrated into USB, and it appeared with more drastic specifications than PC98-NX, which was a hot topic and controversial.

Peripheral device manufacturers, who had been hesitant to manufacture and sell USB devices in the past, have been forced to support USB for the iMac series, which can no longer handle existing interfaces, and the spread has progressed at a stretch. Matched to the iMacTranslucentDesigned USB peripherals became popular and were accepted by a wide range of people. Both Macintosh and Windows drivers are attached to these USB devices, and as a result, it has helped the spread of USB in PC / AT compatibles.

With the advent of USB 3.1 (initially 1 Gbps for Gen 5), only USB-C was adoptedMacBookWas announced on March 2015, 3. The power port also doubles as USB Power Delivery, and it has a bold I / O port configuration that does not even have the conventional USB-A or MagSafe 10.

PC-9821 series

NEC OfPC-9821 seriesHad released a model compatible with USB ahead of other companies, but at the time of the introduction of USB, the PC-9821 series itself was already in the final stage, so the compatible devices are very limited except for NEC devices. However, with Windows 98 SE and Windows 2000, many devices are now working.

game machine

On home video game consolesDream castとXboxAdopted a controller connection with a uniquely shaped terminal that arranged USB. The first to adopt a general-purpose USB terminalPlayStation 2However, it was not actively used except for the connection of some peripherals such as keyboards, mice, and headsets for voice chat. Also, the keyboard and mouse can be used as they are with USB specifications for PC / AT compatibles, but they were not well known.

Appeared in the late 2000sXbox 360,PlayStation 3In addition to connecting a controller, the general-purpose USB 2.0 terminal has flexibility similar to that of a personal computer. AlsoWiiAlso has a USB 2.0 terminal, but its use is limited to connecting network adapters, keyboards, Wii peripherals, etc.

PlayStation 4The actual state of the PlayStation Camera connected to the AUX terminal and AUX terminal is USB 3.0, and it is a terminal with a unique shape to avoid the possibility that communication speed can not be secured by simultaneous connection with other devices.

Of portable game consolesPlayStation Portable,PlayStation VitaIt functions as a USB device by itself, and connects to a PC or PlayStation 3 to exchange data and charge it except for some models.

Recentarcade gamesubstrateNAOMI,SYSTEM246USB cables are physically diverted for I / O communication such as, but this is an industry groupJAMMAJAMMA VIDEO standard established inJVS), And the signal level protocol is not compatible with USB.

Digital home appliances

A mobile phone terminal is connected to a personal computer using a USB cable to exchange and charge data, and to perform data communication using the communication network of a mobile phone. Many of the terminals on the mobile phone side are unique, but some have adopted a general-purpose USB port.Portable music playerMany small devices such as these have a general-purpose USB terminal and connect to a PC.Flat screen tv, AVAmplifier,digital photo frame, DVD / BD recorders / players, etc. also have a USB terminal, and can play multimedia files in a USB memory, digital camera, digital, etc.Video cameraIt is used to connect with.Flat screen tvHas something that can record TV broadcasts on a USB-connected HDD[51].

USB 3.0

It was expected that adopted equipment such as storage equipment would appear as early as the end of 2009.[52].BuffaloIs external with USB 2009 support on October 10, 28Hard disk driveAnd released an interface card for adding a USB 3.0 port. This is the world's first USB 3.0 compatible device and interface card that can be purchased by individuals.[53].. Sold to consumersMotherboard, On the interface board, NEC Electronics (currently:Renesas Electronics) USB 3.0 controller chip andMarvelMadeSATA 3.0 (SATA 6 Gb / s) In many cases, controller chips are mounted on the same board and sold as a single product.

When adding a USB 500 interface card with an effective 3.0 MB / sec, the bandwidth of the additional bus must also be an effective 500 MB / sec, otherwise it will work but the additional bus will be installed.bottleneckBecomesPCI Express The standard one is 2.0 x 1 (effective 500 MB / sec).

In August 2010, there was a problem that the motherboard that adopted the USB-IF unauthenticated controller that appeared in the early stage did not work even if a USB 8.x / 1 device was connected.[54].

Supported OS

USB devices that support the USB 2.0 standard are supported by a wide range of operating systems (OS). The main items are shown below.

In the case of USB class peripherals, it can be used in an OS environment that supports USB class devices. In the case of embedded systems, game consoles, digital home appliances, etc., there may be no or incomplete support for USB class devices on the host side. Also, even if the peripheral device is not a class device, it will recognize the peripheral device for each OS.Driver softwareThe same equipment can be used as long as it is prepared.

USB devices compatible with the USB 3.0 standard, motherboards with built-in USB controllers, interface boards, etc. have begun to appear from the end of 2009 to the first half of 2010.

It is expected that the OS support status will mainly depend on the support of each controller and device driver (including USB 3.0 mass storage, class driver, etc.). If the OS itself is discontinued, it is customary not to receive official driver support.

Major USB devices


[How to use footnotes]

注 釈

  1. ^ Up to 5 unit load. One unit load for USB 1.x and 2.0 is 1 mA.
  2. ^ Up to 6 unit load. One unit load of USB 3.x is 1 mA.
  3. ^ Supports 1.5 A only for Type-C-Type-C cables. 3.0 A is optional. The data protocol is USB 2.0 or USB 3.x.
  4. ^ Type-A / B or Type-C cable.


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  27. ^ Universal Serial Bus Revision 2.0 specification, 6.4.4 prohibited Cable Assemblies
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  30. ^ USB3.0 basic specifications (NEC Electronics)
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  35. ^ https://plus.google.com/+BensonLeung/posts/71FgNerD8TB 2016-10-30 View
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  37. ^ [Shohei Yamada's Re: config.sys] Anyway, the direction of quick charging indicated by Type-C and Galaxy Note 10+ --PC Watch
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  40. ^ People's Network Japanese Edition December 2006, 12
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  42. ^ Mobile phone industry group to cooperate with standardization of chargers(Nikkei BP, June 2009, 6)
  43. ^ Common mobile phone chargers in Europe, agreed by 10 major companies such as Apple, Nokia and RIM(Nikkei IT Pro, June 2009, 6)
  44. ^ Universal Charging Solution
  45. ^ It works! One modified stupidThan.
  46. ^ "iPhone, finally USB "Type-C" installed in the included AC adapter”. Nikkei XTECH. 2021/1/14Browse.
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  48. ^ "Outline of Electrical Appliance and Material Safety Law”. Ministry of Economy, Trade and Industry. 2021/1/13Browse.
  49. ^ http://www3.coara.or.jp/~tomoyaz/higaax08.html#080209 ● Contact R's mystery that saves poor contact USB
  50. ^ "Connecting devices with the" USB 3.0 "that appeared at 5 Gbit / s" Nikkei Electronics October 2008, 10 issue
  51. ^ SHARP LC-22K5 etc.
  52. ^ [PC Watch] NEC Ele develops USB 5 host controller compatible with 3.0 Gbps transfer
  53. ^ World's first !! Hard disk compatible with next-generation high-speed standard USB10, which is 3.0 times higher than before - BuffaloPress Release November 2009, 10
  54. ^ Forefront of technology (2): A dark cloud in USB 3.0 just before its spread? Uncertified products that are not backward compatible are on the market (2/2)


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