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superseded USB 1.1.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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