What is USB? Features of Universal Serial Bus

Friday, December 14, 2012 , ,

Universal Serial Bus
USB Sign

In today's world as we see that the use of USB cables is growing day by day. Now we have all devices USB compatible. Our Mobile Phones  Smart Phones, Modems, Printers and many other peripherals can be connected to a computer via using USB. Now DVD players, and CD ROM devices can also be connected to the computer via USB. So Do you know how this USB constructed and why it is so important to us? Here is a brief introduction to the USB and its various features.
You May Also Like: Introduction & Features Of Microcontroller 8051

USB is an acronym used for Universal Serial Bus. It is a technology that was introduced by a group of technology giants which can make data transfers so fast. It is a very fast bus(Although, it is not a Bus. It Kinda like). It is a connection technology that is used to connect various peripherals to the computer and transfer data to each other at very fast speeds. The USB was invented by a group of technology giants (IBM,Intel,Microsoft,Compaq and Northern Telecom) to make data transfer faster. The first version of USB known as USB 1.0 supports maximum 12 megabits per second. Now its 3rd version is launched. Which is known as USB 3.0 and supports very high data transfer speeds as 4.8 Gigabits per second. New laptops and computers are coming with USB 3.0 pre-installed. A USB can be used to connect any peripheral to the computer. We can connect multiple USB devices and cable to our computer by using a USB hub. By using a USB hub we can connect 127 maximum number of devices to a computer.

Construction of USB:
 A USB has mainly two twisted pairs of wires. One pair is used to carry the power supply required by the device and the other pair is used to carry the data. The USB can draw a maximum of 5V, 500 m Amp current from the host. The host is the computer to which the USB is connected. It can supply the power to the low powered devices which requires less than 5 volts of supply for their operation. If a device requires more power then we have to use external adapter to supply the power to the device. As their is current flow between USB s, therefore we can not connect two Computers or Hosts via USB. As it works with only one host. If we do this then there may be short circuits in the USB cables. A USB can have maximum 5 meter long wire or cable.
You May Also Like: What is PCI Bus? Its Features

Types Of USB:
USB cables are of two different types: One which uses type A connector and the other which uses type B connector. Type A connector is used for upstream end while type B connector is used for downstream end. A USB device also requires drivers to run on a computer. All latest operating systems can automatically install drivers for commonly used USB devices. If the USB device does not get detected by a computer then their must be corruption in drivers. You can get drivers of the device from its vendor.

Features Of USB:
The following are the main features of the Universal Serial Bus:
  • The Personal Computer works as a Host.
  • The Low-powered devices can draw their power from the host via USB. If we have to connect a high power device then we have to use external adapter.
  • USB cable has two twisted pairs of wires. One for the data transfer and the other for power transfer.
  • We can connect maximum 127 USB devices to a host via USB hubs.
  • USB devices are hot swappable  That means we do not have to turn off, On or restart our computer when connecting or disconnecting a USB device.
  • When the computer enters in power saving mode, USB devices also put to sleep by the computer.