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= OVERVIEW =

Universal Serial Bus (USB) was first introduced in 1995 and was designed and developed by seven major companies which include Compaq, Hewlett-Packard, Intel, Lucent, Microsoft, NEC and Philips.[1] Reasons for the development were to provide a standardized and simplification of the I/O (Input/Output) connection for the many different devices to the computer which in turn allows the industry to be forward-moving.[1] Furthermore, USB promotes user-friendliness with its plug and play, automatic device detection and installation capabilities. [1] In today’s world, virtually every Personal Computer (PC) and devices has or uses USB connector.[1] USB port is a port used widely to connect external devices such as printers, digital cameras and mobile phones to PC. Transferring of data from PCs to external devices or vice versa is made possible. Also, it is used as power chargers to some of the portable devices.

= VERSION HISTORY =


 * 1994 Development of USB started by seven companies
 * 1995 USB Implementers Forum (USB-IF) formed. Intel introduced first USB silicon
 * 1996 USB Specification 1.0 released
 * 1998 USB Specification 1.1 released
 * 2000 USB Specification 2.0 released
 * 2008 USB Specification 3.0 released

= USB SPEED =

Various versions of USB were available before USB 1.0 was introduced in January 1996; USB 0.7 to USB 0.9.[2]

USB 1.0
Introduced in January 1996, USB 1.0 has a data transfer speed of 1.5 megabits per second (Low Speed) and 12 megabits per second (Full Speed).[2] Due to timing and power limitations issues in USB 1.0, an upgrade of the USB 1.0 to USB 1.1 was released in September 1998. This improvement made USB 1.1 received wide acceptance as a computer component.[2]
 * USB 1.0
 * Low-speed: 1.5 M bit/s
 * High-speed: 12 M bit/s
 * USB 1.1
 * Low-speed: 1.5 M bit/s
 * High-speed: 12 M bit/s

USB 2.0
Since its introduction in year 2000, USB 2.0 has successfully replaced the original USB by retaining the original’s advantages such as, same power-management mechanisms, cable, connector and backwards compatibility.[2] Transfer rate were improved from 480Mbps to 40X faster than the original USB and higher bus bandwidth was included in USB 2.0.[2] With these improvements, Vendors were able to provide new devices such as, fast storage devices, next-gen scanners and printers whilst retaining the operation of existing peripherals namely keyboard and mouse.[2] USB 2.0 is more reliable and is a breakthrough in USB technology and due to it “Hi-Speed” interfaces, it become popular and widely accepted. It is also backward compatible with USB 1.0.[2] USB 2.0 entered development stage at April 2000 initiated by Hewlett-Packard, Intel, Lucent Technologies, NEC and Philips, and was ready for implementation by the end of 2001. USB 2.0 had increase the data transferring speed from 12 megabits per second in USB 1.0 to 480 megabits per second.[2]
 * USB 2.0
 * High-speed: 480 M bit/s

USB 3.0
USB 3.0 was introduced to tackle new peripherals as there was a need for higher bus bandwidth, better performance and transfer rate.[3] Its transfer rate is 10X faster than USB 2.0 and provided better power efficiency in active and idle mode. Furthermore, it is backwards compatible with devices in USB 2.0 standards. [4]   USB 3.0 specification was released in November 2008. Albeit the usual transfer speed of USB 3.0 is approximately 4 gigabits per second, it has a maximum speed of 5 gigabits per second.[2] This reduces the time required for data transmission and reduces power consumption.[2]
 * USB 3.0
 * Super-speed: 4.8 G bit/s

= CONNECTOR PROPERTIES =

USB is an industry standard and its specification defines the It was intended to standardize the connection; the way to communicate and supply power of computer accessories, human interface devices, and digital electronics to PC. Many old port types such as serial port, parallel port, PS/2 ports impose many limitations. For instance, automatic configuration was not available and hot-pluggable was not possible.[5] USB, on the contrary, supports plug-and-play feature which enables users to use the device upon insertion, that is, users do not need to install any driver for a USB drive to function. However, additional drivers may be installed for certain features of the USB to work. It is also hot-pluggable; allowing users to use USB devices without having to restart their computers.[2] USB successfully replaced earlier connector types which include the serial, parallel, and ps/2 ports.[6] In addition, USB eliminated the need of separate chargers for many portable devices.[6] For some devices which require more than 500mA of current, maximum current supported by a single USB port, a Y-shaped cable with 2 USB connectors to connect to the computer can be used. With a Y-shaped cable, a device can draw total of maximum 1A from the 2 USB ports.[6] // Figure 1 - USB Y cable 1[11] // // Figure 2 - USB Y cable 2[12] // = STANDARD, MINI AND MICRO CONNECTORS =
 * Cables
 * Connectors
 * Protocols used for connection and communication
 * Power supply between computers and electronic devices

Micro USB interface shall become “Universal Charging Solution” (UCS) for mobile phones by 2012.[7] USB ports and connectors are designed in such a way that it's impossible to attach a USB connector wrongly. It supports higher speed than both serial and parallel ports. The connector size of USB is significantly smaller compared to serial and parallel ports. // Figure 3 - USB Connector vs. Serial Connector vs. Parallel Connector Size Comparison[13] // = SYSTEM DESIGN =

Advantages

 * Standardise the ports of all the external devices
 * Hot-swappable i.e. USB drive can be disconnected while the computer is running
 * Plug and play i.e. PCs automatically identify the devices plugged in and load the drivers to interact with the device.
 * High performance and transfer rate.
 * Expandability i.e. a single USB is able to connect up to 127 different devices.
 * Able to supply power to external devices requiring power to operate.
 * Ease of usage as the port and user manual is easy to understand and use.
 * Low cost implementation i.e. most of the USB protocols are standardise and together with simple design, it make USB low cost

Disadvantages
Due to its design, USB is prone to physical damage as it is not strong as certain ports like parallel ports and will be damaged upon impact. Although USB is used to standardise the ports used to connect device to computers, it is still unable to replace some of the ports like Ethernet and VGA/DVI ports as they require to send the signals not in serial but in group or in parallel. = USB ON-THE-GO AND EMBEDDED HOST =

It was designed and built for different USB devices and non-computers (embedded device) to communicate directly and perform basic functions with each other without the need for computer.[8] For example, a digital camera is able to directly connect to a printer and print photos. For its version 2.0 and 3.0, it was included as part of USB 2.0 and 3.0 specification packages respectively.[8] = WIRELESS USB =

It provides a way for devices to connect wirelessly through USB. Wireless connection over radio frequency replaces the need of a physical cable connector, UWB (Ultra-wideband).[9] UWB was chosen as it allows up to 480Mbps of bandwidth which matches with the USB speed of transferring data. However, UWB has an approximately 3 meter range.[9] = BENEFITS OF USB =

USB have standardized ports, resulting in computers having fewer ports to connect to with the same amount of devices as compared to computers with various ports to suit all the different devices’ connectors.[10] In addition, the simplicity of USB’s design enables users to use with relative ease.[10] USB is hot-swappable; as most ports do not allow users to connect or disconnect their devices after their computer is switched on, USB technology allows users to connect/disconnect devices their devices without the need to shut down/restart their computers.[10] This function allows users to add or remove system components without introducing disruption to operations.[10] = GREAT IDEAS OF USB =

USB have changed the way computers design or handle protocols. In the past, a computer is required to have multiple drivers for different ports and devices and it is a requirement to insert the device before the computer is switched on. With the invention of USB, users do not have to restart their system when they connect or disconnect external devices to their computers. USB simplified peripheral connections and is an essential mean for data transfer in digital cameras, mobile phones and portable consoles. Due to its simplicity and ease of use, modern devices are leveraging on this technology to enhance their accessibility. It is a great idea that manufacturers and researchers are brainstorming for possible extension of USB technology to current applications. Last but not least, USB technology has room for improvement and advancement, playing an instrumental role in consumer’s lives. = REFERENCES =

[1] USB.org - Backgrounder. 2011. //USB.org - Backgrounder//. [ONLINE] Available at: []. [Accessed 19 October 2011]. [2] History of USB - USB timeline and its use within computers. 2011. //History of USB - USB timeline and its use within computers//. [ONLINE] Available at: []. [Accessed 19 October 2011]. [3] USB.org - SuperSpeed USB. 2011. //USB.org - SuperSpeed USB//. [ONLINE] Available at: []. [Accessed 19 October 2011]. [4] USB 3.0 Promises Faster Speeds, Backward Compatibility | PCWorld Business Center. 2011. //USB 3.0 Promises Faster Speeds, Backward Compatibility | PCWorld Business Center//. [ONLINE] Available at: []. [Accessed 19 October 2011]. [5] Universal Serial Bus brief Overview, History and Specification. 2011. //Universal Serial Bus brief Overview, History and Specification//. [ONLINE] Available at: []. [Accessed 19 October 2011]. [6] USB Hubs: Daisy Chaining, Bandwidth and Power Demands - TopTenREVIEWS. 2011. //USB Hubs: Daisy Chaining, Bandwidth and Power Demands - TopTenREVIEWS//. [ONLINE] Available at: []. [Accessed 19 October 2011]. [7] 17 Mobile Companies Adopt Micro USB Standard | News & Opinion | PCMag.com. 2011. //17 Mobile Companies Adopt Micro USB Standard | News & Opinion | PCMag.com//. [ONLINE] Available at: [|http://www.pcmag.com/article2/0,2817,2341261,00.asp#fbid=fJDJe5gE6my]. [Accessed 19 October 2011]. [8] USB.org - USB On-The-Go. 2011. //USB.org - USB On-The-Go//. [ONLINE] Available at: []. [Accessed 19 October 2011]. [9] USB.org - Wireless USB. 2011. //USB.org - Wireless USB//. [ONLINE] Available at: []. [Accessed 19 October 2011]. [10] Recommended solution for data storage - FireWire vs. USB 2.0 vs. USB 3.0. 2011. //Recommended solution for data storage - FireWire vs. USB 2.0 vs. USB 3.0//. [ONLINE] Available at: []. [Accessed 19 October 2011]. [11] www.cubeternet.com, (2011), //USB 2.0 Cable Type A Male to A Male (Y)// [ONLINE]. Available at: __http://www.cubeternet.com/catalog/cable_UAmAmY_p.jpg__ [Accessed 19 October 11]. [12] www.bixnet.com, (2011), //USB Y Cable (2 Type A to 1 Mini 5)// [ONLINE]. Available at: __http://ep.yimg.com/ca/I/laptopupgrade_2180_39067503__ [Accessed 19 October 11]. [13] apt.bitcore.org, (2011), //usb-ps2-serial-parallel// [ONLINE]. Available at: __http://apt.bitcore.org/stuff/Stupid%20Pics/usb-ps2-serial-parallel.jpg__ [Accessed 19 October 11].