USB 'On-The-Go'： Next generation USB connectivity for mobile devices capable of point-to-point data exchange

摘要

The Universal Serial Bus (USB) has become as ubiquitous on today's personal computers as the mouse or keyboard, and is often used to connect such devices. Cahners In-Stat Group finds that USB is already present in 99% of PCs shipping today and projects that by 2004, approximately 750 million USB-equipped desktop and notebook PCs will be in use. Moreover, shipments of USB-enabled peripherals are also projected to grow an average of 55% per year through 2004. USB utilizes a traditional master-slave architecture that is both powerful and well suited to PCs and many embedded systems that require device connectivity. In an environment characterized by a diverse array of mobile devices, however, the limitations inherent in the USB architecture pose several challenges. First, it is not possible to connect two masters (hosts) to the same bus. Second, USB does not allow slaves (peripherals), such as PDAs or digital still cameras, to function as a host and connect directly with another device without a PC intermediary.