The USB interface is being rapidly adopted by automakers who like its universality, but the consumer interface is about to change. A faster version is moving into production, underscoring the difficulty of matching automotive design cycles with rapidly changing consumer technologies.
The USB Implementers Forum has completed an upgrade called SuperSpeed USB, which moves data at 5 Gbits/s. That is well above the 480 Mbits/s for the High Speed USB links now in widespread use. First silicon for the standard, completed in November, should ship in the third quarter.
The advance comes just as automakers are deploying the standard, which now ships in 2 billion per year quantities, to connect consumer products to vehicles. iSuppli Corp. predicts that a third of all available vehicle models will offer USB interface options this year, up from 16% in 2008.
However, the emergence of SuperSpeed USB will force automakers to decide whether to design-in a very high-performance version that is more costly or employ the commodity standard now and then migrate when advances throughout the consumer industry create more demand for SuperSpeed USB. Proponents say the latter course may be best.
“The design phase for automakers is long,” said Jeff Ravenscroft, President of the USB Implementers Forum. "It may make sense for some of them to go directly to SuperSpeed."
The new spec could be particularly attractive to consumers who want to bring video or lots of audio into a vehicle. The time savings are minor for files smaller than a gigabyte, but they become increasingly better as volumes rise.
“When you bring something into a car, having high data rates for video or audio lets you play or simply move files quickly,” Ravenscroft said. “Downloading a 5-GB movie using USB 2.0 takes 14 to 15 min. With SuperSpeed, it will take 16 or 17 s.”
The trend toward high-definition video will also create more demand for a high-speed connection for portable products. As navigation systems, video games, and movies all migrate to more realistic images, consumers will be bringing larger files into vehicles.
“Today, automotive screens are good, but they’re low resolution,” Ravenscroft said. “Going forward five years, people are going to want high-definition content, especially for rear-seat entertainment.”
SuperSpeed USB has benefits beyond its basic speed enhancement. It communicates bidirectionally at the peak rate, effectively doubling throughput in the few instances when there is heavy data flow going in both directions.
“We’ve added five wires: two transmit, two receive, and one ground,” Ravenscroft said.
It also reduces power consumption to take some pressure off the vehicle’s electrical system. The host waits for slave devices to tell it they have data to deliver. When there is no communication, devices can conserve power in sleep modes. That is more efficient than with current versions that require the host to poll all USB devices every cycle.