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Can true USB 2.0 of Hub be harnessed being connected to USB 1.1 Onboard Port?

Posted on 2006-05-14
Medium Priority
Last Modified: 2013-11-09
Hi Everyone:

        I have a friend who has ordered a digital camera which does still frames and streaming audio/video data.  The setup requires USB 2.0. Now, as I understand the situation at this time, he has a USB 2.0 Hub which is connected to an older onboard USB 1.1 onboard port.  With this in mind, will the digital camera setup run fine from the USB 2.0 Hub?  

        Even though the USB Hub is 2.0, I still assume it will default to the slower USB 1.1 speed.  Therefore, I believe the logical workaround for this problem will be a PCI to USB 2.0 Converter Card.  However, I am unsure on this one.

         Any shared insights and ideas will be appreciated.  I look forward to hearing from everyone.

        Thank you.

Question by:GMartin
LVL 32

Assisted Solution

jhance earned 200 total points
ID: 16678067
No.  While backward compatible with USB 1.1, a USB 2.0 hub will not be any faster than a USB 1.1 hub.  The camera, unless it requires USB 2.0, would still work in this setup but it will be slow.

If you need USB 2.0, you must start with a USB 2.0 controller.  If your PC doesn't have one, get a plug-in card.  I like the ones from Adaptec but there are many choices.
LVL 23

Assisted Solution

bhanukir7 earned 600 total points
ID: 16678088
hi there

please read this

You can connect USB 2.0 peripherals to USB 1.1 hosts and hubs, and they should work just fine ... but at 12 Mbit/sec, not at 480 Mbit/sec.

To get "high speed" behavior you'll need an updated host controller. It must support "USB 2.0 high speed", through the "EHCI" standard. Today you can get those as PCI cards, usually with a three or five port controller from NEC, or sometimes a four port one from Philips or VIA. More importantly, essentially all current generation PC motherboard silicon includes an EHCI controller built in. Linux users have reported success on most of these, with chips from ALI, Intel, NVidia, SiS, VIA, and others. (That's in alphabetical order; I'm not intending to slight any vendors.) See the section on Linux support (later) for more specific information.

You may also need newer hubs with USB 2.0 support. Probably the most important aspect of such hubs is how they support trees of devices that mix both high speed and full (or low) speed devices. The short version of the story is that to get high speed transfers out of a high-speed capable device, you must hook it up through an EHCI controller (that's using an EHCI driver!), and any hubs between the host and the device must only be USB 2.0 hubs.

coming to the moot point for better speed and usage i suggest using a pci usb 2.0 converter card as this should give u the desired speed. u can go for a usb 2.0 connecter if  ur motherboard supports it. In the new motherboards one usb hub with two boards is onboard and there is a additional slot were u can put a usb hub ports.

so if ur motherboard supports go simply for a additional usb port connector if not the best possible thing is usb pci converter card.


LVL 70

Accepted Solution

garycase earned 1200 total points
ID: 16678315
Hi George,

You're correct in assuming that the interface will work at USB v1.1 speeds.   Think of USB v1.1 and USB v2 as two different size pipes.   If you connect a large diameter pipe to a much smaller diameter pipe, the flow is still constrained by the smaller pipe.   Another analogy I've seen used is a 1-lane highway that expands to a 40-lane highway ==> the overall flow is still restricted to the traffic that the single lane can carry.

While it is true that USB v2 is defined to be backwards compatible with USB v1.1, there are some devices which will NOT function properly at USB v1.1 speeds ==> they simply can't function as designed at the slower data rate.   The camera you've referred to is most likely such a device -- that's why it says it REQUIRES a USB v2.0 interface.   I suspect it will work fine for the transfer of still images, but the streaming video feature will almost certainly not work at v1.1 speed.

Your proposed solution is exactly what you need to do -- get a PCI USB v2 card :-)
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LVL 70

Expert Comment

ID: 16678321
... there are many such cards, but here's one for $7.99 with an $8.00 rebate :-)
LVL 70

Assisted Solution

garycase earned 1200 total points
ID: 16678324

Author Comment

ID: 16714779
Hi Everyone:

       First, I want to sincerely thank each expert for their input.  I found each response to be thorough and well thought out, thus, making this one very difficult when it came to determining which answer to accept.  I must confess I found garycase's feedback easier to follow because of the simple examples used to illustrate or capture his points of view on the matter.  Also, I sincerely appreciate the direct purchase link for the PCI to USB 2.0 Converter Card.  

       In closing, thanks again everyone for your valued insights.  I thoroughly enjoyed reviewing each expert's thoughts on the subject of USB.


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