Universal Serial Bus (USB), with one billion units in the installed base, is the
most successful interface in PC history. Projections are for 3.5 billion interfaces
shipped by 2006. Benefiting from exceptionally strong industry support from all
market segments, USB continues to evolve as new technologies and products come
to market. It is already the de facto interconnect for PCs, and has proliferated
into consumer electronics (CE) and mobile devices as well.
Wireless USB is the first the high speed Personal Wireless Interconnect. Wireless
USB will build on the success of wired USB, bringing USB technology into the wireless
future. Usage will be targeted at PCs and PC peripherals, consumer electronics
and mobile devices. To maintain the same usage and architecture as wired USB,
the Wireless USB specification is being defined as a high-speed host-to-device
connection. This will enable an easy migration path for today's wired USB solutions.
Wireless USB paper takes a brief look at the widely used interconnect standard, USB and in
particular, at the emerging technology of Wireless USB and its requirements and
about any computer that you buy today comes with one or more Universal Serial
Bus connectors on the back. These USB connectors let you attach everything from
mice to printers to your computer quickly and easily. The operating system supports
USB as well, so the installation of the device drivers is quick and easy, too.
Compared to other ways of connecting devices to your computer (including parallel
ports, serial ports and special cards that you install inside the computer's case),
USB devices are incredibly simple!
who has been around computers for more than two or three years knows the problem
that the Universal Serial Bus is trying to solve -- in the past, connecting devices
to computers has been a real headache!
" Printers connected to parallel
printer ports, and most computers only came with one. Things like Zip drives,
which need a high-speed connection into the computer, would use the parallel port
as well, often with limited success and not much speed.
" Modems used
the serial port, but so did some printers and a variety of odd things like Palm
Pilots and digital cameras. Most computers have at most two serial ports, and
they are very slow in most cases.
" Devices that needed faster connections
came with their own cards, which had to fit in a card slot inside the computer's
case. Unfortunately, the number of card slots is limited and you needed a Ph.D.
to install the software for some of the cards.
The goal of USB is to end all
of these headaches. The Universal Serial Bus gives you a single, standardized,
easy-to-use way to connect up to 127 devices to a computer.
Just about every
peripheral made now comes in a USB version. In fact almost all the devices manufactured
today are designed to be interfaced to the computer via the USB ports.
Connecting a USB device to a computer is simple -- you find the
USB connector on the back of your machine and plug the USB connector into it.
If it is a new device, the operating system auto-detects it and asks for the driver
disk. If the device has already been installed, the computer activates it and
starts talking to it. USB devices can be connected and disconnected at any time.
The Universal Serial Bus has the following features:
" The computer acts as the host.
" Up to 127 devices can connect to the
host, either directly or by way of USB hubs.
" Individual USB cables
can run as long as 5 meters; with hubs, devices can be up to 30 meters (six cables'
worth) away from the host.
" With USB 2.,the bus has a maximum data rate
of 480 megabits per second.
" A USB cable has two wires for power (+5
volts and ground) and a twisted pair of wires to carry the data.
the power wires, the computer can supply up to 500 milliamps of power at 5 volts.
" Low-power devices (such as mice) can draw their power directly from
the bus. High-power devices (such as printers) have their own power supplies and
draw minimal power from the bus. Hubs can have their own power supplies to provide
power to devices connected to the hub.
" USB devices are hot-swappable,
meaning you can plug them into the bus and unplug them any time.
USB devices can be put to sleep by the host computer when the computer enters
a power-saving modenbsp;