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New TUSB2077A design is DOA

Phil Roth
Prodigy 60 points
Other Parts Discussed in Thread: TUSB2077A

Designed in the 2077A which seemed straight forward and populated minimal components like crystal, LDO, reset controller, etc...  just to get basic powerup of the device confirmed.  Double and triple checked the assembly and pretty sure the design is wrong.  HUBCFG is aways low so the chip isn't configured on powerup.  This is as basic as it gets, with no eeprom, downstream ports powered with separate supply, etc.  The plan is to slave another 2077a of the root controller for 12 total ports and I can't even get the 1st controller running.  All static voltages on the pins are fine. Would be nice to see any type of activity on some output likes, but nothing is happening on any lines except the xtal inputs  Attached is the schematic and and feedback would be appreciated.

Thanks

Phil16240.pdf

  • 0
    TI__Mastermind 18655 points
    Hello Phil,
    The DP0PUR pin of the TUSB2077A should be connected to the he DP0 pin of the upstream connector through a 1.5KOhm resistor.
    The second USB hub will start enumerating after the first gets enumerated. Therefore, change the timing reset value for the second USB Hub so that it could wait until the first one is enumerated.
    Regards
  • 0 in reply to Joel Jimenez0
    Prodigy 60 points
    Thanks for the suggestions. Connected DPO to DPOPUR with a 1.5kOhm with no success. Understand about delaying reset on the 2nd device but that's not populated yet. I'm thinking about assembling another board with minimal components, just enough to get HUBCFG to be driven HIGH to get confidence my board route is ok, Mind if I ask you to list out minimal components to get the 2077 to configure?
    Phil
  • 0 in reply to Phil Roth
    Prodigy 60 points

    Hi Joel,

    Made good progress here and now the device is recognized by the PC and sending Generic ID info.  Actually had a mirrored footprint on the PCB layout which your advice helped me find. Thanks very much for your help.  I'll start to populate the downstream ports followed by the secondary controller attached to the root hub.

    Again, Thank You

    Phil Roth

  • 0 in reply to Joel Jimenez0
    Prodigy 60 points

    I have the 1st controller working along with 6 downstream ports but the 2nd controller isn't stable on powerup, suspecting I need to wait for the 1st to finish enumerating.... as you mentioned.

    Can I use any signals between the (2)  2077a controllers to synchronize them on powerup, like SUSPEND on the 1st hub connected to RESET on the 2nd?

    If not, can I simply keep the 2nd device under RESET for a period of time after the 1st controller comes out of RESET?

    If yes, what is the min. time for the delay?  I'm hoping 250 milliseconds will be enough.

    Thanks

    Phil

  • 0 in reply to Phil Roth
    TI__Mastermind 18655 points
    Hello Phil,
    I would not suggest using SUSPEND of the 1st hub connected to RESET of the 2nd hub due to the USB host completely controls USB SUSPEND terminal.
    You can hold the RESET on 2st hub low about 10ms to 50ms just after the RESET on the 1st hub is high and stable.
    Regards
  • 0 in reply to Joel Jimenez0
    Prodigy 60 points

    Joel,

    Noted, with thanks.  I've just proven out the prototype and released the design to production.

    Based on your level of support, It seem my choice to use TI was a good one.

    Best Regards

    Phil Roth

  • 0 in reply to Phil Roth
    Prodigy 60 points

    The 12 port hub design is working well but I'm having trouble understanding the individual POWERON signals for each port.  This design always uses remote +5v to power up the ports with the root controllers powered by the PC. I have LEDS on the POWERON signals and thought they would only be active when a device is plugged into a port but they are always on. Connecting the PORT PWR pin to either +5 or GND doesn't make a difference.

    Ideally all port LEDS would be off until a device is plugged in to a port, then that particular LED would go on.

    An easy way to connect another LED showing COMM activity would also be nice, but that would be a luxury at this point.

    Any Advice?

    16241C.pdfThanks