1. The charger itself (or any other device with a USB host) sag when more current is taken from it than it can provide. In normal mode, the voltage at the charging output is maintained at 5.0V - 5.2V
But at the other end of the cable, a drawdown is already possible! The higher quality wires and connectors they use, the less voltage drop. (this is why you won’t be able to squeeze out 2A using a bad cable - the voltage will drop, the phone will see this and curb its appetite)

2+3. The USB standard (up to 2.1 inclusive) obliges device manufacturers to consume no more than 0.5A during operation. In USB 3.0 this threshold is raised to 1A. Moreover, the USB host is not required to support devices with a consumption of even 0.5A - according to the standard, upon initial connection, the device reports how much current it requires to operate, and the host answers whether it can provide it. According to the standard, during initialization the device should not consume more than 0.1A
This is where the phone industry and the microUSB charging connector standard comes into play. When the USB standard, intended for communication, began to be used “stupidly” to provide power to devices, confusion began. If, when connected to a PC, the phone could “ask” how much current it could supply, “stupid” chargers did not support any initialization and connection establishment, and one could take from them... but how do you know how many amperes you can take from charging? How much current does the phone consume when 5 volts is plugged in?? And in general, what if it’s not a stupid charger, but a cable with broken data buses, connected to a PC, from which you can’t take more than 0.5A???
In general, they came up with the idea of ​​checking whether the data buses are closed, and if they are closed, take, for example, 1A. For other manufacturers, such as Apple, the charger supplied a certain voltage to the data bus, which the phone detected, recognized the charge as “its own” and consumed, for example, 2A.
Then Qualcomm came up with QuickCharge, made smart charging and sent as many as 9 volts through the cable instead of 5. In new versions, the voltage rose to 12, and then even to 20. And all this via USB... Something took me to the wrong place. What's the next point?

4. I didn’t see any fuses in the chargers. Usually the voltage sags, up to four volts. At this voltage, the phone can no longer take many amperes and automatically reduces the current consumption.

5. The standard voltage at which devices can theoretically be charged is in the range of 4.0-5.5 volts (I have a charger with 5.5). With QuickCharge 3.0 - voltage up to 20 volts. Depending on the quality of the cable, up to 2 amperes can flow through it. Well, maximum 3, no more - the contact point will overheat and everything will melt.

6. In what direction? Charging is generally a by-product of the USB standard. If you're talking about connecting your phone to a PC and charging it, this usually always works. If OTG - on my phone I managed to make it charge at the same time. But not always. In this mode, according to the USB standard, the phone must serve as a power source, and not vice versa, be charged from the device connected to it.

Connectors on the computer system unit are often sorely lacking, so many users purchase additional devices - hubs. But not everyone understands electronics, and often there is a lack of power supply to the USB hub port. Anyone who encounters such a message on the monitor screen has to figure out what to do in this situation.

What is a USB hub

Initially, the USB (USB) standard was designed to connect third-party telecommunications devices to computers. Who would have thought that today almost every conceivable technology is connected to this port:

• Low-power speakers;
• Keyboards;
• Mice;
• Modems;
• Portable flash drives;
• Charging cables for smartphones, etc.

Thus, there is a dissonance between the need to connect several devices to the machine and the limited number of ports. For example, the latest model MacBook computer has only one slot of this type: as a result, it will be impossible to charge the device and use a flash drive at the same time.

One way to get around the flaws of computer manufacturers may be to purchase special equipment - a USB hub. This miracle, when connected to a port, gives several output sockets at once, into which several devices can be inserted.

Types of concentrators

There are several modifications of hubs on sale:

1. Connected directly to the system board. In order to use this type of device, you will need to remove the cover of the PC case. For those who are not entirely confident in their computer literacy, it is better not to buy such equipment. In case of an error, the damage will be estimated at thousands of rubles.
2. The second category of these devices is much easier to use, since they can be connected to one of the USB sockets located outside. The number of connectors available at the output can reach 5. However, it is better not to connect some energy-intensive devices to them.
3. The third type of hubs is generally similar to the previous one, with only one exception: in addition to connecting to a computer, they need power from the network for their stable operation. This solves the problem with energy-hungry peripheral computer devices.
4. The fourth group of concentrators has a very highly specialized field of application. Namely, they are suitable only for portable portable PCs (laptops)

What does a hub port lack of power mean?

This is a fairly common problem with type 2 hubs. Let us highlight the main possible causes and ways to resolve them:

• There are too many power-hungry devices connected to the hub. The equipment simply cannot cope with the load placed on it. The only thing that can be recommended as a way out of the situation is to turn off too “gluttonous” devices.
• If this error is typical for absolutely all ports of the hub, then most likely the problem is in the hub itself. As a rule, this indicates a broken wire or problems with the hub chip.
• Another common problem is related to using so-calledUSB extenders. This is a cable (usually 1-2 meters long), which is often purchased by owners of mobile Internet modems in order to place the Internet device closer to the window. However, cheap Chinese cables have incredibly high resistance, and virtually no energy reaches the device. In this case, it is worth purchasing a more expensive cable from a famous brand.

Increasing port power

In order to supply more power via USB, you need to follow several steps:

1. Find out all the information about your computer and its structural components. This can be easily done using the Everest utility. To do this, just run the scan and wait a few minutes. After that, find the item with the motherboard model.
2. If the board model allows for increased power supply through the ports, then the next step is to open the BIOS settings window. Then you need to increase the indicator to the maximum, exit the program and save the settings. In the case of outdated models of mother cards, this cannot be done, so the only way out of the situation is to update the computer.
3. You can also purchase a separate power supply that connects to this type of socket.
4. Another way to fix the problem is to use a special adapter that increases the voltage supply. At the same time, you should pay attention to the quality of the product, since cheap crafts labeled “made in China” tend to damage the ports.

How to choose an active hub?

Perhaps the surest way to provide sufficient power to each USB device is to buy a splitter that receives additional power from a regular electrical outlet and distributes it at the output.

Here are the ingredients for a successful purchase:

1. You shouldn't skimp on a quality device. The price of good hubs can reach up to 3,000 rubles, but such gadgets are worth the money.
2. You should not contact Chinese online stores. Firstly, the quality of these devices without a name is very controversial. Miracle machines from the Middle Kingdom have broken the computer of more than one gullible user. Secondly, delivery from China can take a month or more. Therefore, the best way to buy a good product here and now is to visit the page of a large chain store.
3. Pay attention to the brand. Recognized masters in their field: Hama, TP-Link and Greenconnect. It is better not to buy unknown brands.
4. The distance between the jacks on the hub also matters. Some users complain about the lack of space to connect all the necessary devices.
5. If you have the opportunity to hold the equipment in your hands, you need to estimate its mass. It should be neither too small nor too large.
6. Carefully inspect the power cable and its attachment location. This is one of the most common “sore spots” of hubs.

The use of cheap power strips in combination with power-hungry devices is the most common reason why a USB hub port lacks power. What to do depends on financial resources.

USB (Universal Serial Bus) - The USB data transfer interface is widespread today, used in almost all devices - phones, PCs, MFPs, tape recorders and other devices - used both for data transfer and for charging phone batteries.

Types of USB connectors.

There are a large number of types of USB connectors. All of them are shown below.

Type A- active, power supply device (computer, host). Type B- passive, connected device (printer, scanner)

USB cable pinout by color.

USB 2.0 pinout.

USB is a serial bus. It uses 4 shielded wires: two for power (+5v & GND) and two for differential data signals (labeled D+ and D-).

USB micro

USB micro has been used since 2011 in phones, MP3 and other devices. Micro is a newer variation of the mini connector. It has the advantage of connecting connectors, the connector is connected tightly to the plug and provides a tight connection.

The USB interface began to be widely used about 20 years ago, to be precise, since the spring of 1997. It was then that the universal serial bus was implemented in hardware in many personal computer motherboards. Currently, this type of connecting peripherals to a PC is a standard, versions have been released that have significantly increased the data exchange speed, and new types of connectors have appeared. Let's try to understand the specifications, pinouts and other features of USB.

What are the advantages of Universal Serial Bus?

The introduction of this connection method made it possible:

• Quickly connect various peripheral devices to your PC, from the keyboard to external disk drives.
• Make full use of Plug&Play technology, which simplifies the connection and configuration of peripherals.
• Refusal of a number of outdated interfaces, which had a positive impact on the functionality of computing systems.
• The bus allows not only to transfer data, but also to supply power to connected devices, with a load current limit of 0.5 and 0.9 A for the old and new generations. This made it possible to use USB to charge phones, as well as connect various gadgets (mini fans, lights, etc.).
• It has become possible to manufacture mobile controllers, for example, a USB RJ-45 network card, electronic keys for entering and exiting the system

Types of USB connectors - main differences and features

There are three specifications (versions) of this type of connection that are partially compatible with each other:

1. The very first version that has become widespread is v 1. It is an improved modification of the previous version (1.0), which practically did not leave the prototype phase due to serious errors in the data transfer protocol. This specification has the following characteristics:

• Dual-mode data transfer at high and low speed (12.0 and 1.50 Mbps, respectively).
• Possibility of connecting more than a hundred different devices (including hubs).
• The maximum cord length is 3.0 and 5.0 m for high and low transfer speeds, respectively.
• The rated bus voltage is 5.0 V, the permissible load current of the connected equipment is 0.5 A.

Today this standard is practically not used due to its low throughput.

1. The dominant second specification today... This standard is fully compatible with the previous modification. A distinctive feature is the presence of a high-speed data exchange protocol (up to 480.0 Mbit per second).

Due to full hardware compatibility with the younger version, peripheral devices of this standard can be connected to the previous modification. True, the throughput will decrease up to 35-40 times, and in some cases more.

Since these versions are fully compatible, their cables and connectors are identical.

Please note that, despite the bandwidth specified in the specification, the actual data exchange speed in the second generation is somewhat lower (about 30-35 MB per second). This is due to the implementation of the protocol, which leads to delays between data packets. Since modern drives have a read speed four times higher than the throughput of the second modification, that is, it does not meet current requirements.

1. The 3rd generation universal bus was developed specifically to solve problems of insufficient bandwidth. According to the specification, this modification is capable of exchanging information at a speed of 5.0 Gbit per second, which is almost three times the reading speed of modern drives. Plugs and sockets of the latest modification are usually marked blue to facilitate identification of belonging to this specification.

Another feature of the third generation is an increase in the rated current to 0.9 A, which allows you to power a number of devices and eliminate the need for separate power supplies for them.

As for compatibility with the previous version, it is partially implemented; this will be discussed in detail below.

Classification and pinout

Connectors are usually classified by type, there are only two of them:

Note that such convectors are compatible only between earlier modifications.

In addition, there are extension cables for the ports of this interface. At one end there is a type A plug, and at the other there is a socket for it, that is, in fact, a “mother” - “father” connection. Such cords can be very useful, for example, to connect a flash drive without crawling under the table to the system unit.

Now let's look at how contacts are wired for each of the types listed above.

USB 2.0 connector pinout (types A and B)

Since the physical plugs and sockets of early versions 1.1 and 2.0 do not differ from each other, we will present the wiring of the latter.

Figure 6. Wiring the plug and socket of type A connector

Designation:

• A - nest.
• B – plug.
• 1 – power supply +5.0 V.
• 2 and 3 signal wires.
• 4 – mass.

In the figure, the coloring of the contacts is shown according to the colors of the wire, and corresponds to the accepted specification.

Now let's look at the wiring of the classic socket B.

Designation:

• A – plug connected to the socket on peripheral devices.
• B – socket on a peripheral device.
• 1 – power contact (+5 V).
• 2 and 3 – signal contacts.
• 4 – ground wire contact.

The colors of the contacts correspond to the accepted colors of the wires in the cord.

USB 3.0 pinout (types A and B)

In the third generation, peripheral devices are connected via 10 (9 if there is no shielding braid) wires; accordingly, the number of contacts is also increased. But they are located in such a way that it is possible to connect devices of earlier generations. That is, the +5.0 V contacts, GND, D+ and D-, are located in the same way as in the previous version. The wiring for Type A socket is shown in the figure below.

Figure 8. Pinout of Type A connector in USB 3.0

Designation:

• A – plug.
• B – nest.
• 1, 2, 3, 4 – connectors fully correspond to the pinout of the plug for version 2.0 (see B in Fig. 6), the colors of the wires also match.
• 5 (SS_TX-) and 6 (SS_TX+) connectors for data transmission wires via the SUPER_SPEED protocol.
• 7 – ground (GND) for signal wires.
• 8 (SS_RX-) and 9 (SS_RX+) connectors for data receiving wires using the SUPER_SPEED protocol.

The colors in the figure correspond to those generally accepted for this standard.

As mentioned above, a plug from an earlier model can be inserted into the socket of this port; accordingly, the throughput will decrease. As for the plug of the third generation of the universal bus, it is impossible to insert it into the sockets of the early release.

Now let's look at the pinout for the type B socket. Unlike the previous type, such a socket is incompatible with any plug of earlier versions.

Designations:

A and B are plug and socket, respectively.

Digital signatures for contacts correspond to the description in Figure 8.

The color is as close as possible to the color markings of the wires in the cord.

Micro USB connector pinout

To begin with, we present the wiring for this specification.

As can be seen from the figure, this is a 5 pin connection; both the plug (A) and socket (B) have four contacts. Their purpose and digital and color designation correspond to the accepted standard, which was given above.

Description of the micro USB connector for version 3.0.

For this connection, a characteristically shaped 10 pin connector is used. In fact, it consists of two parts of 5 pin each, and one of them fully corresponds to the previous version of the interface. This implementation is somewhat confusing, especially considering the incompatibility of these types. Probably, the developers planned to make it possible to work with connectors of earlier modifications, but subsequently abandoned this idea or have not yet implemented it.

The figure shows the pinout of the plug (A) and the appearance of the micro USB socket (B).

Contacts 1 to 5 fully correspond to the second generation micro connector, the purpose of the other contacts is as follows:

• 6 and 7 – data transmission via high-speed protocol (SS_TX- and SS_TX+, respectively).
• 8 – mass for high-speed information channels.
• 9 and 10 – data reception via high-speed protocol (SS_RX- and SS_RX+, respectively).

Mini USB pinout

This connection option is used only in early versions of the interface; in the third generation this type is not used.

As you can see, the wiring of the plug and socket is almost identical to the micro USB, respectively, the color scheme of the wires and the contact numbers are also the same. Actually, the differences are only in shape and size.

In this article we have presented only standard types of connections; many manufacturers of digital equipment practice introducing their own standards; there you can find connectors for 7 pin, 8 pin, etc. This introduces certain difficulties, especially when the question arises of finding a charger for a mobile phone. It should also be noted that manufacturers of such “exclusive” products are in no hurry to tell how the USB pinout is done in such contactors. But, as a rule, this information is easy to find on thematic forums.

USB (Universal Serial Bus- “universal serial bus”) - a serial data transfer interface for medium-speed and low-speed peripheral devices. A 4-wire cable is used for connection, with two wires used to receive and transmit data, and 2 wires to power the peripheral device. Thanks to the built-in USB power lines allows you to connect peripheral devices without its own power supply.

USB Basics

USB cable consists of 4 copper conductors - 2 power conductors and 2 data conductors in twisted pair, and a grounded braid (screen).USB cables have physically different tips “to the device” and “to the host”. It is possible to implement a USB device without a cable, with a “to-host” tip built into the housing. It is also possible to permanently integrate the cable into the device(for example, USB keyboard, Web camera, USB mouse), although the standard prohibits this for full and high speed devices.

USB bus strictly oriented, i.e. it has the concept of “main device” (host, also known as a USB controller, usually built into the south bridge chip on the motherboard) and “peripheral devices”.

Devices can receive +5 V power from the bus, but may also require an external power supply. A standby mode is also supported for devices and splitters upon command from the bus, removing the main power while maintaining standby power and turning it on upon command from the bus.

USB supportsHot plugging and unplugging of devices. This is possible due to the increase in the length of the grounding contact conductor in relation to the signal ones. When connected USB connector are the first to close grounding contacts, the potentials of the housings of the two devices become equal and further connection of the signal conductors does not lead to overvoltages, even if the devices are powered from different phases of a three-phase power network.

At the logical level, a USB device supports data transfer and reception transactions. Each packet of each transaction contains a number endpoint on the device. When a device is connected, drivers in the OS kernel read a list of endpoints from the device and create control data structures to communicate with each endpoint on the device. The collection of endpoints and data structures in the OS kernel is called pipe.

Endpoints, and therefore channels, belong to one of 4 classes:

• continuous (bulk),
• manager (control),
• isochronous (isoch),
• interrupt.

Low speed devices such as a mouse cannot have isochronous and flow channels.

Control channel designed for exchanging short question-answer packets with the device. Any device has control channel 0, which allows the OS software to read brief information about the device, including manufacturer and model codes used to select a driver, and a list of other endpoints.

Interrupt channel allows you to deliver short packets in both directions, without receiving a response/confirmation, but with a guarantee of delivery time - the packet will be delivered no later than in N milliseconds. For example, used in input devices (keyboards, mice or joysticks).

Isochronous channel allows you to deliver packets without a guarantee of delivery and without replies/confirmations, but with a guaranteed delivery speed of N packets per bus period (1 KHz for low and full speed, 8 KHz for high speed). Used to transmit audio and video information.

Flow channel provides a guarantee of delivery of each packet, supports automatic suspension of data transmission due to device reluctance (buffer overflow or underrun), but does not guarantee delivery speed and delay. Used, for example, in printers and scanners.

Bus time is divided into periods, at the beginning of the period the controller transmits the “beginning of period” packet to the entire bus. Then, during the period, interrupt packets are transmitted, then isochronous ones in the required quantity; for the remaining time in the period, control packets are transmitted, and lastly, stream packets.

Active side of the bus is always the controller, the transfer of a data packet from the device to the controller is implemented as a short question from the controller and a long response from the device containing data. The packet movement schedule for each bus period is created jointly by the controller hardware and driver software; for this, many controllers use Direct Memory Access DMA (Direct Memory Access) - mode of data exchange between devices or between the device and the main memory, without the participation of the Central Processor (CPU). As a result, the transfer speed is increased since data is not sent back and forth to the CPU.

The packet size for an endpoint is a constant built into the device's endpoint table and cannot be changed. It is selected by the device developer from among those supported by the USB standard.

USB Specifications

Features, advantages and disadvantages of USB:

• High transfer speed (full-speed signaling bit rate) - 12 Mb/s;
• The maximum cable length for high transfer speed is 5 m;
• Low-speed signaling bit rate - 1.5 Mb/s;
• The maximum cable length for low communication speed is 3 m;
• Maximum connected devices (including multipliers) - 127;
• It is possible to connect devices with different baud rates;
• There is no need to install additional elements such as terminators;
• Supply voltage for peripheral devices - 5 V;
• The maximum current consumption per device is 500 mA.

USB signals are transmitted over two wires of a shielded 4-wire cable.

USB 1.0 and USB 2.0 connector pinout

Type A		Type B
Fork (on cable)	Socket (on the computer)	Fork (on cable)	Socket (on peripheral device)

Names and functional assignments of USB 1.0 and USB 2.0 pins

Data 4 GND Ground (body)

Disadvantages of USB 2.0

At least the maximum USB 2.0 data transfer rate is 480 Mbit/s (60 MB/s), in real life it is unrealistic to achieve such speeds (~33.5 MB/s in practice). This is due to the large delays on the USB bus between the request for data transfer and the actual start of the transfer. For example, FireWire, although it has a lower peak throughput of 400 Mbps, which is 80 Mbps (10 MB/s) less than USB 2.0, actually allows for greater data transfer throughput to hard drives and other storage devices. In this regard, various mobile drives have long been limited by the insufficient practical bandwidth of USB 2.0.