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TUSB8041: TUSB8041

Part Number: TUSB8041
Other Parts Discussed in Thread: TUSB8042

Hi Team,

Question about TUSB8041I.

I built HUB with two ‘steps, all connection USB3 as in datasheet

Checked for performance on USB3 – only port A works

All others don’t work,  at USB2 all work correct

See the plot, I can send full scheme next week

Any thoughts why?

Thanks,

Shlomi

TUSB8041.docx

  • Shlomi,

    To clarify USB 2.0 works on the TUSB8041 ports, is this correct? Is the DFP that the TUSB8041 is connected to USB 3 capable? Would it be possible to see a schematic for this design?
  • Hi Malik,

    Here are details

    1. attached scheme

    2. I built few boards, they all operate correct at USB2.0 3. Trying to operate USB3.0  :

      - portA (downstream from 'top' hub) -  ok

      - ports B,C,D,E  :  not recognized

         See in the attached plot the device manager screen

         Seem as the lower level hub is 'unknown USB device'

    4. I connected two YUSB8041-EVM,  they work correct at USB3.0

    Need your help.

    Thanks,

    Shlomi

    vyoshi_21may18_01.pdf

  • Hi Shlomi,

    The USB 3.0 connection between the hubs is going into compliance mode - this occurs when the polling times out during the first connection after power on reset. You should be able to adjust the reset timing between the hubs to fix this issue. To determine which hub is going to compliance mode - try resetting the top level hub to see if the issue clears, if not reset the bottom level hub. If the top level hub is the issue, I would recommend lengthening the reset to this hub so the bottom level hub exits reset before it does.

    You can also try swapping to the pin compatible TUSB8042 which implemented a spec change that prevents entry to compliance mode unless a specific command is sent.

    Regards,
    JMMN
  • Hi JMMN,
    Status :
    I added TPS2001 switch to control VBUS of 'lower HUB'
    And connected GRSTZ of both HUBs to capacitors (as in TUSB8041-EVM) Timing of USB_VBUS ports is very similar between my board and two EVMs Still no success. Lower-HUB can't operate at USB3.0
    Can you send recommended scheme for two (or more) TUSB8041 on same board?
    Thanks,
    Shlomi
  • Hi Shlomi,

    That is very strange. Have you confirm that doing an extra reset to the hub tier#1 brings the connection out of compliance mode?

    Thanks!
    JMMN
  • Hi JMMN,

    Yesterday I do many test with my boards, when I connect to one board I detect first TUSB8041 as USB3 and second TUSB8041 as USB2. When I connect 2 boards so first TUSB8041 in each board use as USB3 and second TUSB8041 in each board use as USB2.

    Do you know if 2 x TUSB8041 that very close one to second can cause this problem?

    Attached pictures of the block diagram and board.

    BTW - Can we have a conference call today? If yes please send me mail to shlomi@telsys.co.il

    Thanks,

    Shlomi

  • Hi JMMN,

    Yesterday I do many testing, when I connect one board the first TUSB8041 detect as USB3 and the second TUSB8041 detect as USB2.

    When I connect 2 boards, each of first TUSB8041 detect as USB3.

    My concern that because the TUSB8041 is very close one to other it cause problems,

    Does TI have experience with board that have 2 x TUSB8041 and both TUSB8041 detect as USB3?

    Attached block diagram and picture of my board.

    BTW - Can you free today for conference call? If yes please send me mail to shlomi@telsys.co.il

    Thanks,

    Shlomi

     

  • Hi JMMN,
    No need conference call, found the problem...
    I connected TXp to TXp, TXm to TXm....
    Should connect TXp to RXp etc.
    I think that you don't look at the scheme :-)
    Thanks,
    Shlomi
  • Glad you found the problem! I'm surprised the TX to TX, RX to RX connection reported as the link being stuck in compliance mode. I didn't think to double check the connections since the link was in compliance mode. Make sure there is a set of series caps near the source of each TX pair.

    Regards,
    JMMN
  • Hi JMMN,

    following this discussion I fixed the scheme and going to produce PCB soon appreciate your help to check the schematic.

    Thanks,

    Shlomi

    VYOSHI_HUBs_13jun18.pdf

  • Shlomi,

    Your posted schematic looks good. When populating your boards make sure that the ground pads for both hubs have a good connection to ground.