IRVINE, Calif. TransDimension Inc. says the host/slave controller it will unveil Wednesday (Nov. 7) is the first single-chip device to comply with the emerging USB On-The-Go specification, which links portable digital devices directly, without a host PC.
Philips Semiconductors said it also plans to offer an On-The-Go host/device controller based on the company's experience with the ISP1161, a USB 1.1 chip developed for embedded systems.
On-The-Go, a supplement to the USB 2.0 spec, was developed in response to the embedded world's demand for point-to-point mobile interconnectivity.
With On-The-Go, the PC is no longer needed to bridge two USB products to transfer data. A compliant MP3 player, for example, can directly talk to another MP3 player to transfer music files. The spec needs a new controller chip that can function as both USB host and slave, independent of a CPU used in embedded systems.
David Murray, vice president of mar keting at TransDimension, explained a few newly defined basic requirements for compliant ICs.
First, On-The-Go, whose 0.9 version was released in early September, lets a small USB connector fit the mobile form factor. On-The-Go also requires a far lower power draw to preserve the battery life of such portables as digital cameras, cell phones PDAs and MP3 players. The spec is meant to "upgrade the current USB 'slave' device" by letting it feature built-in "hosting functions," Murray said.
Though many semiconductor companies offer standard USB controller chips today, designing an On-The-Go chip requires custom skills and substantial knowledge of embedded systems, Murray said.
TransDimension's On-The-Go chip, OTG243, executes all USB transfer descriptors in hardware in its host controller instead of running them in software on a CPU of a portable system. Specifically, it offers on-chip memory for execution of such transfer descriptors for faster data transfer, with minimal intervention of the de vice microprocessor.
TransDimension's OTG243 host/slave controller, priced at $5.99 each in 10,000 units, will start sampling early next year. The company has been shipping a host-only USB controller for embedded systems since December.