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TUSB8020B: TUSB8020B booting pc thru

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Replies: 6

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Part Number: TUSB8020B

Hi, I want to use the TUSB8020B 1-2 USB hub in a design. One requirement is that we can boot a PC from windows 10 on a USB stick.
Other hubs we have tries works fine. The TIDA-00287 reference design using the TUSB8020B however does not boot. The USB stick
is not found by the BIOS. A power-up problem?

Could you please point me in the right direction. Is this an issue of setting a pin on the device hi/lo?

Why do some hubs work when other doesnt when booting?

Best regards,

Fredrik Kempe

Comex Electronics AB

6 Replies

  • Hi Fredrink,

    Is the boot drive a USB 2.0 stick or USB 3.0 stick?  Not all platforms support USB 3.0 boot.  Also, since the TIDA-00287 is bus powered, can you confirm that the design is powered up in time for the BIOS?

    Regards,

    JMMN

  • In reply to JMMN:

    Hi,

    we use a USB 3.0 stick. It seems to be a timing issue. The reference board (TIDA-00287) starts up a tad to late - and the BIOS doen´t find the USB stick in time at boot-up.

    Other of-the-shelf 1-2 hubs we have tried works though. I really just wanted to find out if this is a known issue. And if there is a simple fix with the TI part (TUSB8028B) such
    as setting it in a different mode.

    Regards,
    Fredrik

  • In reply to Fredrik Kempe:

    Hi Fredrik,

    This isn't a known issue, but we may be able to identify the delay causing the issue.

    Once VBUS is applied to the hub, the hub EVM will need to power on, exit reset and configure itself.  Then the hub will need to be enumerated by the host controller.  It seems like the hub is seen by the BIOS properly (can you confirm this?) so the problem is likely with the time to turn on downstream port power to the USB 3.0 stick.  The TUSB8020B reference design is configured for battery charging so there may be an extra delay while it swaps from battery charging mode to normal mode, so one option is to disable battery charging.  Another option is to set the hub to not be full power managed and leave power on to the downstream ports at all times.

    Are you able to modify the EVM?  I can suggest some reworks to test these options.  I do not have that particular reference design in my lab since it was done by a 3rd party.

    Regards,

    JMMN

  • In reply to JMMN:

    Ah, my mistake... this reference design does NOT have battery charging enabled.  Do you have the ability to externally power the USB 3.0 stick drive and see if it is seen by the BIOS?

  • In reply to JMMN:

    Hi,

    absolutely - we can experiment with the reference board. The TUSB8020B datasheet seems to point at pins 4 and 6 (PWRCTL/BATENx). The should be at a logical 0 now - will check this. Pulling them high
    might help.

    We can also power the memory stick externally and see if it works. Will let you know.

    Regards,

    Fredrik

  • In reply to Fredrik Kempe:

    Hi Fredrik,

    The PWRCTL/BATENx pins are sampled at power on / reset to set battery charging enable or disable.  So if you pull these pins high you will enable battery charging.  I would recommend trying to directly externally power the downstream device, this would likely have the quickest enumeration.

    Regards,

    JMMN

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