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TUSB8041 OTP

Rick H
Prodigy 60 points

Other Parts Discussed in Thread: TUSB8041

We are having issues with the SS Hub not being recognized. The HS hub performs correctly. On the 3.0 device it comes up as an unrecognized device with the yellow ! icon. We copied the reference design onto our card. Also have a reference board that performs correctly. My question is do we have to do anything with the OTP? We are not using SMB or the EEprom.

  • 0
    TI__Guru 60870 points

    Hi Rick,

    You should not need to touch the OTP for normal operation.  OTP can be used to configure some options (VID , PID, etc) but the USB 3.0 portion of the hub should work without it.  Is this an embedded application?

    Regards,

    JMMN

  • 0 in reply to JMMN
    Prodigy 60 points
    Thanks, you previous answers to the voltage timing seems to be the answer. I put a larger cap on Grstn and it appears to have cured the issue.
  • 0 in reply to Rick H
    Prodigy 60 points
    Next question, there seems to be a logic issue. If I plug in a 3.0 device and then a 2.0 device it keeps the 3.0 device as 3.0, but if I plug in a 2.0 device first it doesn't recognize the 3.0 device as 3.0. Is this normal?
  • 0 in reply to JMMN
    Prodigy 60 points
    Do you have to have the DM and DP 2.0 pins connected to operate the 3.0?
  • 0 in reply to Rick H
    TI__Guru 60870 points
    Per the USB 3.0 specification, you should have both sets of signals connected. The hub is designed to work with simultaneous connections on SS and HS on the upstream port, since it does not convert between SS and USB 2.0 speeds. The downstream ports can work at SS, HS, FS, LS or in the case of another USB 3.0 hub being connected: SS and HS.
  • 0 in reply to Rick H
    TI__Guru 60870 points
    On the same port? Or different ports at the same time?
  • 0 in reply to JMMN
    Prodigy 60 points

    On the same port, if I only want 3.0 on this port do I need the 2.0 data connections hooked up? Is there a use for the 2.0 pins in a 3.0 connection?

  • 0 in reply to Rick H
    TI__Guru 60870 points

    If you attach a USB 3.0 device to a downstream port of the TUSB8041, the USB 2.0 pins will not be used while the SuperSpeed connection is present.  There are two reasons why it is a good idea to still connect the USB 2.0 lines:  if the TUSB8041 is connected to a USB 2.0 host, then the USB 3.0 device will still be accessible at USB 2.0 speeds and also, many BIOSes will load USB at USB 2.0 speed during system boot.

  • 0 in reply to JMMN
    Prodigy 60 points
    Thanks, Understood. Our task at hand is we cannot get our board to recognize a 3.0 downstream device. The computer sees the Generic Superspeed Hub, so that part works, we just cannot get it to recognize any of the downstream devices as 3.0. We are routing all connections to a D Sub connector, so they are close together, would that cause the issue?
  • 0 in reply to Rick H
    TI__Guru 60870 points
    Yes, USB 3.0 is very sensitive to noise and impedance mismatches. Does the host controller ever attempt to load the downstream devices? Can you download the usbview.exe from Microsoft and determine if the downstream devices ever attempt to connect at USB 3.0? Also, try updating your USB host controller drivers, so of the older versions do not support low power states on hubs correctly.