Dr. Joan Bushwell's Chimpanzee Refuge

USB 3.0

This week’s Electronic Engineering Times features a short article on the upcoming USB 3.0 spec. The main highlight is a target transfer rate of 4 Gigabits/second (10 times the current rate) providing usable data at 300 Megabytes/second. This rate would challenge IEEE 1394 (AKA FireWire). USB 3.0 is being referred to as “Super Speed USB” and will be “hardware agnostic” according to the article, meaning it could be implemented over copper or optical cabling.

This third variant on the USB theme will adopt a new physical layer, splitting data and acknowledge signals onto separate paths. On the downside, it is likely that USB 3.0 will require a reduction in maximum cable lengths from 5 meters to 2 meters.

The USB crowd is claiming that 3.0 will supplant FireWire, but the FireWire folks themselves are hard at work extending the current 800 Megabit/sec transfer to 3.2 Gigabits/sec. The FireWire spec is due out next year while USB 3.0 silicon is expected in 2009.


  1. #1 craig
    September 27, 2007

    Unless they change USB in version 3.0 to allow node to node communication, as FireWire does, instead of “speak-when-spoken-to” host control, then USB 3.0 will not be a suitable replacement for firewire for things like easy snagging of video off of digital camcorders, etc.

  2. #2 JimFiore
    September 27, 2007

    To quote the article:

    “In place of the polling and broadcast mechanisms used in USB today, the new spec will employ a packet-routing technique and only allow data transmissions when end devices have data to send.

    The new link also will support multiple flows per device and is capable of maintaining separate priority levels for each flow. The capability could be used to end interrupts that cause jitter in video transmissions. The flow mechanism also can enable native command queuing to optimize disk drive traffic. ”

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