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USB without a PC? USB On-The-Go go!

The biggest problem with USB has been that it is PC-centric; You always need a PC in the USB set up. That was until USB On-The-Go.

USB On-The-Go is a supplement to the USB 2.0 standard which takes into account the problems of mobile devices. It is designed to allow PDAs and other mobile devices to be plugged into each other and use USB as their communication link. Why do this? Well, if you are designing a PDA, then you can make the USB connector more than just a way of hot syncing to PCs. The same connector could let you plug into a phone and use it as a modem, plug two MP3 players together to swap music, or any other situation where you just don't have a PC to hand.

It isn't full USB of course. The spec limits the hosting required by the "A device" (that's the device that has classically been a PC) so that it doesn't demand all the bells and whistles that a hosting PC can offer. It also has a lower power requirement so that battery powered devices can power the USB bus. Finally, it's all topped off by a smaller USB connector for mobile devices, with tight limits on how big the overhanging plug molding should be so you don't get connectors covering up other ports which on a mobile device may be quite close together.

Of course, all this USB goodness depends on the take up of USB2.0, but this extension makes implementing USB2.0 for handheld devices a much more useful proposition. You can read about USB-to-go at the USB On-The-Go developer pages where you'll find the just released revision 1.0 of the specification with all the gory details.

And while you are there, check out the list of contributing companies to the specification. Nokia, Palm, Qualcomm, HP, Microsoft, TI, Philips and more. This leads one to suspect that USB On-The-Go is going to be turning up sooner rather than later if it has that kind of backing. We shall see ...