The Universal Serial Bus (USB) peripheral interface has become ubiquitous across all personal computing platforms as well as many industrial and infrastructure platforms.

The release of the USB 1.1 specification combined with the native operating system support offered by Microsoft enabled the rapid adoption of USB hosts in the PC. It also drove the conversion of many peripheral devices from legacy interfaces such as serial (RS- 232), PS-2 (mice and keyboards), and parallel ports (Centronix and IEEE-1284 for printers) to this common interface standard. With the release of the USB 2.0 specification enabling a higher speed connection, an even greater explosion in the number of USB peripherals available greatly enhanced the end-user experience.

The USB is a host-centric bus. In other words, the host must initiate all transfers, both outbound and inbound. The specification defines three basic types of devices: host controllers, hubs, and functions (peripherals or targets are also used interchangeably with the word function). The physical interconnect is a tiered-star topology with a hub at the center of each star. Each wire segment is a point-to-point connection between the host and a hub or function, or a hub connected to another hub or function. The addressing scheme used for devices in a USB system allows for up to 127 devices to be connected to a single host. These 127 devices can be any combination of hubs or peripherals. A compound or composite device will account for two or more of these 127 devices.

USB 2.0 is the current revision of the specification and it fully superseded USB 1.1. The beauty of USB 2.0 is that it maintained full backwards compatibility to USB 1.1 devices. However, it added a much needed third speed node, high-speed (480 Mbps), along with keeping both low-speed (1.5Mbps) and full-speed (12 Mbps) support. In July 2003, the USB OTG addendum was released defining a new class of devices aimed at portable, battery-powered devices.

TI USB Solutions

TI's high-performance portfolio includes fully compliant USB hub controllers, peripheral devices, transceivers, power management products and streaming audio devices. In addition to a broad range of silicon solutions, TI has the support tools, software, documentation, and systems expertise to help simplify design and speed your time to market.

With the MSP430F55xx family of devices, intuitive evaluation tools, and a library of USB software, designers are prepared to implement USB in their projects today!”

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