Universal Serial Bus (USB) is a serial bus standard for connecting peripherals to a host. It was designed to allow peripherals to be connected using a single standardized interface and to improve plug and play capabilities by allowing peripherals to be connected or disconnected without having to reboot the computer or turn the device off. This technology can connect devices including mice, keyboards, gaming controllers, scanners, digital cameras, printers, digital media players, flash drives and external hard drives. It has become the standard connection method for the majority of consumer electronic devices. To date, billions of USB devices have been introduced into the consumer electronics market.
The USB Implementers Forum, Inc. (USB-IF) is a non-profit corporation founded by leading companies in the computer and electronics sectors. The organization was formed to provide a support organization and forum for the advancement and adoption of the technology. The Board of Directors is currently comprised of the following companies: Hewlett-Packard Company, Intel Corporation, LSI Corporation, Microsoft Corporation, NEC Corporation and ST-Ericsson.
USB 1.0 AND 1.1
The 1.0 specification was introduced in 1994 with two data rates, Low-Speed (1.5 Mbps) and Full-Speed (12 Mbps). It was designed to replace the myriad of connectors at the back of PCs and simplify software configuration of communication devices. The specification was released in 1998 and was the earliest revision to be widely adopted.
The 2.0 specification was released in 2000 and was standardized by the USB-IF in 2001. Several companies led the initiative to develop a higher data transfer rate of 480 Mbps, about 40 times faster than the 1.0 specification. Also known as Hi-Speed USB, 2.0 expanded the range of external devices that could be used on a computer and offered backward compatibility with previous generations.
Many USB devices are portable, and there is an increasing need for devices to communicate directly with each other without a computer. The On-The-Go Supplement makes it possible for peripherals to communicate directly with each other. Its features include:
- Limited host capability to communicate with selected peripherals
- A small connector appropriate for the mobile form
- Low power requirements for preserving battery life
- Ability to be either host or peripheral and to dynamically switch between the two.
Wireless USB is a short-range, high-bandwidth wireless radio communication technology. Designed from the ground up to address challenges of wireless communications and personal networking, this technology combines the speed and security of wired technology and the ease-of-use of wireless technology. It can be used in devices including game controllers, printers, scanners, digital cameras, digital music players, hard disks and flash drives. It can also transfer parallel video streams.
It is capable of sending date at a rate up to 480 Mbps at a 3 meter distance and up to 110 Mbps up to 10 meters. It was designed for the 3.1 to 10.6 GHz frequency range. The Wireless USB architecture allows up to 127 devices to connect directly to a host. With the elimination of wires, a hub is not needed. An upcoming Wireless 1.1 specification will increase data transfer speed to 1.0 Gbps per second.
In November 2008, the USB 3.0 Promoter Group announced the completion of the 3.0 specification. It delivers transfer rates up to 10 times faster than 2.0 through the utilization of a 5.0 Gbps data rate. Additionally, it has optimized power efficiency, sync-n-go technology that minimizes user wait-time and backward compatibility with the 2.0 standard. Thse SuperSpeed devices interoperate with 2.0 platforms and SuperSpeed USB hosts support Hi-Speed legacy devices.
NEC Electronics recently announced the first USB 3.0 host controller (part number PD720200). With its high-speed data transfer capability, the new SuperSpeed host controller will require only 70 seconds to transfer 25 GB of HD video content, the equivalent of a Blu-Ray disc. Transferring the same content would take upwards of 14 minutes with Hi-Speed USB.
Advances in USB technology will lead to a new generation of high-performance, consumer electronic products. For assistance with product development, the SuperSpeed Platform Integration Lab (PIL) is now open for USB-IF members. This lab provides 3.0 developers with the opportunity to test host and device interoperability. For more information, visit the PIL testing page.
USB connectors are designed for ease-of-use. Generally, the trident logo on the connector should be facing up when plugging into a port. The connectors are designed to be durable and easy to insert/remove. Different types of connectors server different functions. The Standard-A plug is frequently on cables permanently attached to devices, such as computer keyboards or mice. The Standard-B plug typically plugs into devices with removable cables, such as a printer. USB device connectors have evolved and become smaller as consumer electronics devices have also become smaller in size since the initial technology was developed. The current standard connector for small devices such as mobile phones and cameras is the Mirco-B connector.
For a company to use a USB logo, its product must be compliant as demonstrated by passing a Compliance Test Program. When a certified logo appears on a product, consumers know the product has passed the standards set by the organization.
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