What are USB devices? Working, Types & Applications

The Universal Serial Bus, commonly known as USB is one of the most popular devices that is a part of our everyday life. But due to their ease of use, we never bothered to learn about its technical aspects. So, in this article, we will discuss how a USB works. We will also learn the fundamental concepts behind USB and realize how this tiny device makes our life easier.

What is a USB?

USB is a connection interface for devices like a personal computer, to connect other electronic accessories like a keyboard, mouse, printer, etc to itself. It is also used to connect the devices to their chargers. The USB interface is an industry standard for short-distance digital data communications.

It is a simple and extremely flexible mode of connection and exists in both wired and wireless types. The wired version is more opted than the wireless version since it comes with ports and cables. A USB is shown in the figure below.

USB (Universal Serial Bus)
USB (Universal Serial Bus)

Where are USBs commonly used?

The USB has three main purposes:

  • For interfacing two devices. For example: When we connect a mouse to our computer.
  • For digital data transfer. For example: When we connect our mobile phones to personal computers for data transfer.
  • To supply electric power across cables. For example: When we connect mobile phones to the adapters via USB for charging.

How does a USB Work?

The device to which the USB is connected is known as the host. For example, a laptop or a PC is a host. When the host is switched on, it checks for the devices connected to it and assigns an address to each one of them. This process is called enumeration. The host then determines the mode of data transfer that needs to be performed depending on the device connected.

The following three modes of data transfer are performed through the USB interface:

Interrupt Mode:

It’s termed as an interrupt because very little data is sent in this process. The devices like the mouse and keyboard send data in the interrupt mode.

Bulk Mode:

Almost in a reverse case, big packets of data are sent in bulk mode. The printer is a good example of a device that transfers data in bulk mode.

Isochronous Mode:

This mode is supported for streaming devices like speakers. A real-time data transfer happens between the host and the speaker.

Since the devices are enumerated to the host, it keeps track of the bandwidth requested by the connected devices. The USB divides the bandwidth into frames and these frames are controlled by the host. Each frame contains 1,500 bytes and a new frame starts after every millisecond.

Looking for the Pinout of USB Connectors?

What is a USB Port and Connector?

The space to plug in the USB is known as a USB port. The head of the USB cable that goes into the port is the connector. In a desktop computer, the USB ports are located behind the CPU, while laptops have USB ports on either side. A USB connector and port are shown in the figure below.

A USB connector and port
A USB connector and port

We just need to plug in the connector to the USB port to initiate the process. The operating system automatically detects the device and installs the driver. This process happens only if a new device is connected to the system. Once it is installed, the system starts the communication.

What are the types of USB connectors?

There are two types of USB connectors available on a USB cable, i.e., A and B connectors.

Types of USB ports and connectors
Types of USB ports and connectors

A Connector:

  • Upstream connector
  • Heads to the system

B Connector:

  • Downstream connector
  • Heads to the device

Thus, the ‘A’ head should be connected to the system and the ‘B’ head should be connected with the device.

The USB ports are also available in different physical layouts as given below.

  • USB-A (Type A)
  • USB-B (Type B)
  • USB-C (Type C)
  • Micro USB

If the available interface does not match with the port, using the same cable you can connect to a different port. The USB cables are manufactured to support all combinations of ports and connectors.

Looking for the Pinout of USB Connectors?

What are the advantages of USB?

To find the real advantage of these devices, let’s travel back to the period when USBs were not in the picture.

The connection between the two devices was a serious concern at that time. There was no generalized or common mode of connection.

  • Printers were connected through parallel ports.
  • Modems were usually connected through serial ports.
  • Some devices had their own cards for connection.

The major issue behind these connections was that the computers had at most one or two such ports. Thus, it was difficult to connect more than two devices. For example, the PC may not have more than two parallel ports, so connecting more than two printers was impossible. This was a huge drawback faced in those days.

The USB then emerged as a game-changer.

  • It was standardized.
  • It had a simple interface.
  • It supported many devices.

The mouse, keyboards, printers, modems, card readers, and many other devices could now be easily connected to the PC.

Now, it is a global solution for the connection of miscellaneous electronic accessories to the system. Today, computers have at least four inbuilt USB ports. Similarly, every peripheral is now designed with a USB version.

What is a USB Cable? Why are they used?

USB cable
USB cable

The above figure shows that connector heads are attached to both ends of a cable, popularly known as a USB cable. They are widely used for transferring and storing data. It enables a simple and effective connection of peripheral devices to the computer.

The USB cables opt over other parallel and serial cables due to some remarkable benefits. Some of them are mentioned below.

Faster Data Transfer:

The USB cables carry more information in a given time frame as compared to parallel cables. The data transmission speed in a USB cable is 12 Mbps, while that of a parallel cable is 115 kbps.

Smaller Port Size:

The size of a USB port is smaller as compared to the other ports. Thus, only a limited space has to be reserved for the port in laptops. This helps in manufacturing thinner and compact laptops.

USB Hub:

USB cables are compatible with USB hubs so that multiple devices can be connected to the system at a time.

Charging Devices:

The capability to function as charging cables is a significant advantage of USB cables, which is an important feature that other cables lack.

Hot Pluggable:

The USB cables are known as hot plugs because there is no issue in connecting or removing USB cables while the computer is running.

Universal Standard:

The USB cable is established as a universal standard and hence, it is easily available at reasonable prices.

How to fix USB device not recognized error?

It is usually very hard to find a solution if our USB port stops working. But here you will find a detailed structured explanation on how to troubleshoot this issue. The flowchart present below will help you to figure out the exact reason why your USB is not detected by the system.

USB Troubleshooting flowchart
USB Troubleshooting flowchart

If your USB is not detected by your PC, restart your system and again check the connection status. If it’s still not detected, then follow this systematic troubleshooting process. The issue might be with the hardware or with the software.

Hardware Issue:

  • In order to address any hardware issue, the first step is to shut down the system.
  • Then try to use another USB port in the system.
  • If that works, that particular USB port is defective.
  • If the above method doesn’t work, then the issue might be with the system. If the system is failed, a detailed checking is necessary for the PC.
  • If the issue is with a particular port, check whether any dust is collected in the port. The dust in the port reduces airflow and causes overheating. Remove the dust and check again.
  • Sometimes, the port becomes loose for the connector due to regular use. This can be fixed by changing the board.

Software Issue:

To start troubleshooting on the software side, the first step is to open Device Manager and check whether your device is listed in it. The step-wise procedure to open Device Manager is given below:

  1. Go to the Start menu
  2. Open Device Manager
  3. Select USB Controller
  4. Check whether the device is listed as a USB Host Controller
  • If the device is not listed as a USB Host Controller, there are two options to try out.
    • Click Scan for hardware changes in Toolbar. This will scan the connected hardware and include the device in the list.
    • Uninstall USB Host Controllers and install it again. This process may find the device during the re-installation.
  • If the device is listed as a USB Host Controller and still not working, the USB controller might be suspended by the ‘Power Saving Mode’. Do the following steps to disable this feature.
    • Go to Control Panel
    • Click Power Options from Hardware and Sound.
    • Find the selected plan and click Change Advanced Plan Settings from Change Plan Settings
    • Find USB Settings
    • Disable the option USB Selective Suspend Setting.

What is a USB Hub? What is it used for?

A USB hub
A USB hub

A USB hub is a collection of USB ports. The figure above shows a USB hub where you can connect multiple USB devices to a single network.

The figure above shows a USB hub where you can connect multiple USB devices to a single network.

The USB hub is available in two types: powered and unpowered. The selection of the correct hub depends on the USB device. For example, if a device has no internal power supply like a mouse or a keyboard, using a powered hub is necessary. In the case of high-powered devices like printers and scanners, the power is acquired from the computer, and thus an unpowered hub can be used.

A powered hub is a better option if the devices are connected to a laptop. Since the powered hub supplies power to the devices by itself, they do not rely on the laptop battery. Otherwise, the battery drains at a faster rate if multiple devices are connected through the hub.

What are the benefits of using a Hub?

Here are some of the benefits of incorporating a USB hub in a network.

  • A low-cost device.
  • Run multiple components at a time
  • Increases the speed of data transfer
  • Increases the computer speed
  • Faster charging
  • Charge multiple devices at a time
  • Capable to run heavy-duty components.
  • More durable
  • Less damage to the laptop

What are the most commonly used USB Devices?

Nowadays, most of the peripherals are connected to the system with a USB interface. These devices include:

  • Printers
  • Keyboards
  • Mouse
  • Scanners
  • Digital cameras
  • Joysticks
  • Modems
  • Webcams
  • Flight yokes
  • Storage devices
  • Network adapters
  • Storage devices
  • Scientific data acquisition devices

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