Spec gives you USB on the go
By Greg Vrana -- EDN, January 10, 2002
One of the criticisms of the USB interface has been its lack of support of peer-to-peer connections. If you wanted to move a song from one MP3 player to another, for example, you had to connect them to a PC, move the MP3 file from the first player to the PC, and then move the file from the PC to the second MP3 player. To solve this problem, the USB 2.0 Promoters Group has created the USB On-the-Go Supplement to the USB 2.0 specification (see "Understanding USB On-the-Go," EDN, Nov 22, 2001). You can access Revision 1.0 of the supplement, which was released on Dec 18, 2001, at www.usb.org/developers/onthego.
In line with this new spec, Transdimension offers the single-chip, $5.95 (10,000) OTG243 USB On-the-Go host/function controller to help you create USB devices that can communicate with each other without connecting them to a PC. Transdimension claims that the OTG243 will allow manufacturers to add USB peer-to-peer connectivity for much less than the cost of adding an IEEE 1394 port, which already supports peer-to-peer connections.
The OTG243 controller has on-chip memory and targets devices that can't afford to devote a lot of processor resources to its USB connection. By locating only active endpoint and transfer descriptors in controller memory, the OTG243 can efficiently process transactions and reduce system bus contention. The controller supports 12- and 1.5-Mbps USB 2.0 devices. You can choose between an 80-pin LQFP or a BGA package; Transdimension also licenses the intellectual-property core.
Transdimension, 1-949-727-2020, www.transdimension.com.
