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TUSB8041: When does the setting written by SMB become effective

Conor
Guru 12065 points
Part Number: TUSB8041

Hi, 

Please tell me about the specifications of the USB3.0 HUB TUSB8041.

I'm thinking of connecting an MCU to the SMB terminal of the TUSB8041 and writing various settings. In that case, please tell me the specification of the timing to write with SMB.

・When does the setting written by SMB become effective?
・What happens if I set from SMB after communication has started on the USB UP side (after communication such as GET DESCRIPTER)?

Thanks,

Astro

  • +1
    TI__Guru*** 144925 points

    Astro:

         if you want to change  configuration with SMBUSz , you need to pulldown  SMBUSz . The hub will not start USB enumeration until configuration is done.

    regards

    Brian

    .

  • 0 in reply to Brian Zhou
    Guru 12065 points

    Hi, Brian

    Conor said:
    ・What happens if I set from SMB after communication has started on the USB UP side (after communication such as GET DESCRIPTER)?

    Just in case, I would like to confirm the above items.
    As far as the datasheet is concerned, the specification is that SMBus mode is terminated by clearing cfgActive.
    After starting communication on the USB UP side, what will happen if you try to set via SMBus?

    Thanks,

    Astro

  • 0 in reply to Conor
    TI__Guru*** 144925 points

    if SMBusz is low, Hub will not start USB communication . Unless SMBus is high first , once USB communication started, then you set SMBus to low. Is this what you want to do?

    regards

    brian

  • 0 in reply to Brian Zhou
    Guru 12065 points

    Hi,brian

    I was planning to use the default value of the built-in OTP or connect an external EEPROM, but I'm thinking of deleting the EEPROM to reduce costs and connecting the MCU to the SMB terminal to write various settings.

    For foolproof purposes, I would like to know what kind of operation will occur when setting from SMB after communication starts on the USB UP side.

    Thanks,

    Astro

  • 0 in reply to Conor
    TI__Guru*** 144925 points

    Then, just PD SMBusz pin. when device is powered on, it will configure with SMBusz first. After configuration is done, it will start USB communication.

    regadrs

    brian