USB On-the-Go (OTG): Uses and Support

Abstract: USB On-the-Go (OTG) allows two USB devices to talk to each other without requiring the services of a personal computer. Although OTG appears to add \"peer to peer\" connections to USB, it does not. Instead, USB OTG retains the standard USB host/peripheral model, where a single host talks to USB peripherals. OTG introduces the dual-role device (DRD), capable of functioning as either host or peripheral. Part of the magic of OTG is that a host and peripheral can exchange roles if necessary.

Before OTG, the concept of an embedded host was already established in the USB world. Instead of duplicating the full UHCI/OHCI USB controllers and drivers built into personal computers, most embedded host chips provide limited hosting capabilities. This makes them better suited to the embedded environment than to the PC with its huge resources and infinite capacity for drivers and application software.