>>>>>> Sounds like it's a 1.1 device to me. >>>>> >>>>> Yep, that's what it sounds like to me too. >>>>> >>>>> Dale >>>> >>>> But that's OK isn't it? I don't need 2.0 speeds between each webcam >>>> and the controller, I just need the increased overall bandwidth of a >>>> 2.0 controller so one of the 1.1 webcams doesn't use all of it. >>> >>> The 2.0 controller doesn't _have_ increased bandwith if it's >>> talking to 1.1 devices. In that case, the 2.0 controller is >>> transferring data at the same speed as a 1.1 controller. >> >> I thought the total bandwidth available for a controller was different >> than the bandwidth at which it communicates with one device. You're >> saying any 1.1 device that uses 12 mbit/s will 100% monopolize a 2.0 >> controller so no other devices can function? >> > > Yes. USB is not like 1394/Firewire. Firewire will increase and > decrease bandwidth as different devices take control of the bus. There > is negotiation between devices and the device that owns the bus > controls how the bus is used. > > With USB a 1.1 device on the bus causes the 2.0 controller to operate > at 1.1 speed so there is only 12Mb/S on that bus once you plug the 1.1 > web cam in. > >> Taking a different approach, since I have 2 USB controllers (EHCIx1, >> OHCIx1) why can't I operate one webcam on one controller and one >> webcam on the other controller so they can both function? >> > > If the hardware is working correctly, if the drivers are independent, > and IF IF IF the two physical ports you chose are actually going to > completely different controllers then you can. I do this. This sort of > thing becomes an issue with USB when you make a mistake an plug an old > USB mouse or keyboard into the wrong physical port and bring your 2.0 > bus speed down to 1.1 bandwidth.
That's a lot of IFs. This USB PCI card looks good because it claims: "Five ports in three independent host controller design, two OHCI and one EHCI" http://www.newegg.com/Product/Product.aspx?Item=N82E16815104202 Are you saying I can't count on this card behaving as 3 separate USB controllers? - Grant > Over and out, > Mark > >> - Grant >> >>>> I get the feeling I have a misconception somewhere along the >>>> line here. Could someone straighten me out? >>> >>> A Corvette going 3MPH will get to the finish line at exactly >>> the same time as a 4-year-old kid on a tricycle going 3MPH. It >>> doesn't matter what the controller is capable of -- it matters >>> what speed it's actually talking. >>> >>> -- >>> Grant
