Universal Serial Bus (USB)

USB was designed to standardize the connection of peripherals like pointing devices, keyboards, digital images and video cameras. But some devices such as printers, portable media players, disk drives, and network adaptors to personal computers used USB to communicate and to supply electric power. It is commonplace to many devices and has largely replaced interfaces such as serial ports and parallel ports. USB connectors have replaced other types of battery chargers for portable devices with themselves. 

What is a Universal Serial Bus(USB)?

Universal Serial Bus (USB) is an industry standard that establishes specifications for connectors, cables, and protocols for communication, connection, and power supply between personal computers and their peripheral devices. There have been 3 generations of USB specifications: 

• USB 1.x
• USB 2.0
• USB 3.x

The first USB was formulated in the mid-1990s. USB 1.1 was announced in 1995 and released in 1996. It was too popular and grab the market till about the year 2000. In the duration of USB 1.1 Intel announced a USB host controller and Philips announced USB audio for isochronous communication with consumer electronics devices.

In April of 2000, USB 2.0 was announced. USB 2.0 has multiple updates and additions. The USB Implementer Forum (USB IF) currently maintains the USB standard and it was released in 1996. 

USB Connector Types

USB connectors have different shapes and sizes. Most of the USB connectors are the standard USB, Mini-USB, and Micro-USB, which have two or more variations of connectors. Information on each type are shown below.

Mini USB

Mini USB is available in three different types A type, B type, and AB type. It is used with computer peripherals and digital cameras. The most common kind of interface is this one, that is referred to as mini B. Micro USB and USB-C cables basically take the place of mini USB on the latest devices. It uses coaxial cable to transmit data and power between two devices. it applies to mobile hard drives, digital cameras, and MP3 players. One end of a micro USB cable has a much smaller quadrilateral hub, and the other end has a regular USB hub with a flat head. It can be easily plugged into mobile devices. Although the tiny USB is mainly designed for, it can also be used to transfer data between computers having at least one USB port for charging device.

Micro USB

A reduced version of the USB (Universal Serial Bus), the micro-USB. It was created for connecting small and mobile devices including digital cameras, smartphones, GPS components, MP3 players, and photo printers and was first announced in 2007 as a replacement for mini USB.

The three different types of Micro-USB are Micro A, Micro B, and Micro USB 3. The connector size for the type Micro-A and Micro-B is 6.85 x 1.8 mm, while the Micro-A connector has a larger maximum overmild size. Because it has more pins on the side for twice as many wires than micro B, USB 3 micro is more comparable to micro B yet has faster speed. Micro USB and normal USB versions are both plug-and-play and hot-swappable is still widely used with electronic devices.

USB Type-C

A USB Type-C port is a relatively new type of connector that may be found on the majority of contemporary newer Android smartphones and other USB-connected devices. Data and power are delivered to computing machines using it. In contrast to traditional USB connections, USB-C cables can be connected into devices in either direction, including upside down.

USB Transfer Speeds

Since it is an external bus standard, USB 1.0 can accommodate up to 127 peripheral devices and data transfer rates of 12 Mbps.

The USB 2.0 standard, commonly referred to as high-speed USB, was created in 2001 by Philips, Lucent, Microsoft, Hewlett-Packard, Intel, NEC, and Compaq. It can support a transfer rate of 60 megabytes per second or more up to 480 Mbps.

USB 3.0, generally known as SuperSpeed USB 3.0, was made accessible for the first time by Buffalo Technology in November 2009. The enhanced functionality and speed of USB 3.0 contributed to advancements in power management, improved bandwidth capacity, and USB 2.0 technology.

Up to 5.0 gigabits per second (Gbps), or 640 megabytes per second, can be supported. After the release of USB 3.1, its name was changed to USB 3.1 Gen1 for manufacturing considerations. With the release of their Dell XPS and Inspiron computer series in April 2011, Dell began to roll out USB 3.0 connections.

The most recent version of the USB protocol commonly known as SuperSpeed, that was made available until July 31, 2013, is USB 3.1. It can support transfer rates of up to 10 Gbps. Recently, USB 3.0 and 3.1 revisions are used by different devices to improve speed and performance.

Advantages of USB

The Universal Serial Bus was designed to simplify and improve the interface between personal computers and peripheral devices when compared with previously existing standard or ad-hoc proprietary interfaces.  

1. The USB interface is self-configuring. This means that the user need not adjust settings on the device and interface for speed or data format, or configure interrupts, input/output addresses, or direct memory access channels. 
2. USB connectors are standardized at the host, so any peripheral can use any available receptacle. USB takes full advantage of the additional processing power that can be economically put into peripheral devices so that they can manage themselves. USB devices mostly do not have user-adjustable interface settings. 
3. The USB interface is hot pluggable or plug and plays, meaning devices can be exchanged without rebooting the host computer. Small devices can be powered directly from the USB interface thus removing extra power supply cables. 
4. The USB interface defines protocols for improving reliability over previous interfaces and recovery from common errors. 
5. Installation of a device relying on the USB standard minimal operator action is required. 

Disadvantages of USB

1. USB cables are limited in length. 
2. USB has a strict tree topology and master-slave protocol for addressing peripheral devices. Peripheral devices cannot interact with one another except via the host, and two hosts cannot communicate over their USB ports directly. 
3. Some very high-speed peripheral devices require sustained speeds not available in the USB standard. 
4. For a product developer, the use of USB requires the implementation of a complex protocol and implies an intelligent controller in the peripheral device. 
5. Use of the USB logos on the product requires annual fees and membership in the organization. 
    

Comparison of USB 1.x, USB 2.0, and USB 3.x

Note: USB 3.x includes USB 3.0, USB 3.1, and USB 3.2. The USB 3.2 standard also includes two additional transfer modes: SuperSpeed+ (SS+) and SuperSpeed+ (SS++) which can transfer data at up to 20Gbps and 40Gbps respectively.