New USB spec offers two-way power flows AND double-sided plug

Your mobe could charge your laptop

USB 3 logo

The USB Promoters Group has loosed the USB Power Delivery v2.0 and USB Billboard Device Class v1.0 specifications on the world.

Don't snore, dear readers, because these specs make it possible to reverse the role of devices popped into USB plugs.

As the 534-page Power Delivery v2.0 spec (contained in this 42-megabyte .zip file) explains, the new standard “... allows a Source and Sink to swap power roles such that a Device could supply power to the Host. For example, a display could supply power to a notebook to charge its battery.” The standard also explains how to make such power transfers possible with USB hubs. Plenty of monitors already include USB hubs, albeit with a connection back to the host PC. This spec could therefore offer a way to turn a monitor or other device into a power source for several gadgets.

Video-over-USB is an old trick and the extra bandwidth of USB 3.0 makes it more practical, so this new spec could lead to the humble USB cable taking on a very important role. It may also be worth considering that USB power packs are the accessory du jour for mobile phones: this spec could make them practical ways to extend laptops' operating hours too.

The release of the standards makes it possible for gadget-makers to start work on such applications, but only over the forthcoming reversible “USB Type-C” connectors. Those plugs will use something new called “Alternate Modes” that represent “an option that permits a vendor or standards organization to utilize the USB Type-C cable and connector and provide additional features.” Which is to say features like the power-reversal caper described above.

But before anyone can put the Alternate Modes to work, they need the USB Implementers Forum to issue them with a standard or vendor ID (SVID). But before you can get an SVID you need to be using USB Power Delivery v2.0 and USB Billboard Device Class v1.0.

So to complete our circumnavigation of this standards acronym thicket, the new standards make it possible to build kit that uses the new Type-C connector and unleash the new things that Type-C connectors and the new power delivery standards enable.

Isn't the way the world gets built just great? ®

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