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TUSB8020BEVM: Host enumeration and single down stream port use

Kelly Wang
Intellectual 550 points
Part Number: TUSB8020BEVM
Other Parts Discussed in Thread: TUSB8020B

I am designing a circuit to use TUSB8020B as a repeater to extend USB 3.0 communication distance. Before circuit design, I try evaluate it by using its demo board  TUSB8020BEVM. I have several question regarding this demo board and TUSB8020B,

1. What is the maximum cable length allowed between host and upstream USB B connector on TUSB8020BEVM while still reach SS data rate of 5G or so?

2. What is the maximum cable length allowed between downstream USB A connector on TUSB8020BEVM to USB device while still reach SS data rate of 5G or so?

3.  If only one downstream port will be used, can all signal pins that are related to another downstream port left float open?

4. The demo board will enumerate on host no matter when it is attached to host through cable no matter whether there is device attached to downstream port or not. Is there a way to configure it only enumerate on host when a USB device attached to down stream port and let the host only enumerate the attached device instead of TUSB8020BEVM?

5. If somehow host only can enumerate TUSB8020BEVM as TUSB8020BEVM, not attached usb device, manufacture string and product name needs to be changed through SMbus. Is there a software tool and configuration fixture to use to configure it through SMbus? Or configure the dedicated I2C EEPROM so that TUSB8020BEVM can be configured through I2C from the EEPROM?

6. Does TUSB8020BEVM need a dedicated driver to be installed on host?

Thank you in advance.

  • 0
    TI__Guru 60870 points

    Hi Kelly,

    1. What is the maximum cable length allowed between host and upstream USB B connector on TUSB8020BEVM while still reach SS data rate of 5G or so?

    [TI] USB 3.0 cables are typically maximum = 3M, USB 2.0 cables are typically maximum = 5M.

    2. What is the maximum cable length allowed between downstream USB A connector on TUSB8020BEVM to USB device while still reach SS data rate of 5G or so?

    [TI] USB 3.0 cables are typically maximum = 3M, USB 2.0 cables are typically maximum = 5M.

    3.  If only one downstream port will be used, can all signal pins that are related to another downstream port left float open?

    [TI] Yes

    4. The demo board will enumerate on host no matter when it is attached to host through cable no matter whether there is device attached to downstream port or not. Is there a way to configure it only enumerate on host when a USB device attached to down stream port and let the host only enumerate the attached device instead of TUSB8020BEVM?

    [TI] No, USB hubs must be enumerated as devices on the USB to work properly even if no downstream device is connected.

    5. If somehow host only can enumerate TUSB8020BEVM as TUSB8020BEVM, not attached usb device, manufacture string and product name needs to be changed through SMbus. Is there a software tool and configuration fixture to use to configure it through SMbus? Or configure the dedicated I2C EEPROM so that TUSB8020BEVM can be configured through I2C from the EEPROM?

    [TI] TI provides an EEPROM programming tool but the hub will only pull in data from the EEPROM immediately after a hard rest to the device (using GRSTz), so the values cannot be changed depending on what device is connected.

    6. Does TUSB8020BEVM need a dedicated driver to be installed on host?

    [TI] No, USB hubs use generic operating system drivers.

    Regards,

    JMMN

  • 0 in reply to JMMN
    Intellectual 550 points

    JMMN,

    Thank you very much for your reply! I didn't find information on the EEPROM programming tool. Would you like to give me a link

    Kelly

  • 0 in reply to Kelly Wang
    TI__Guru 60870 points

    Please accept my friend request and I will send it directly.

    Regards,

    JMMN

  • 0 in reply to JMMN
    Intellectual 550 points

    JMMN,

    I have accepted your friend request.

    Regards,

    Kelly