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Original question:

TUSB8044: schematic check

TUSB8044: TUSB8044 active reset: Hub cannot recognized by my SoC

Colin Liu
Prodigy 10 points
Part Number: TUSB8044

Tool/software:

Hi Sir,

We are using TUSB8044 hub upstream port to connect to my SoC USB3.1 controller transceiver.

  1. But when we did manual reset GRSTz (active reset), our SoC just cannot find the hub (the power seq is correct VDD33 is stable before VDD11).
  2. On the contrary, when we used passive reset GRSTz (4.7uF), we have 30% possibility to find the hub even though the power up sequence is incorrect (VDD33 leads VDD11).
  3. When we use passive reset and corrected power sequence, our SoC just cannot find the hub (the power seq is correct VDD11 is stable before VDD33)

Could you please advise what method or I2C register we can check whether the hub boots up correctly?

Attached is block diagram for your review.

BR,

Colin

  • 0
    TI__Guru*** 145435 points

    Hi Colin:

      Is the red path for hub upstream ?

         IS USB2 hub detected?

       Is  Ethernet device detected by SOC?

      Do you have AC cap between hub upstream to SOC for both TX and RX?

    Regards

    Brian

  • 0 in reply to Brian Zhou
    Prodigy 10 points

    Hi Brain,

    Thanks for your prompt response.

    Yes, Ethernet device detected.

    Yes, AC coupling cap added.

    We found the issue could be cleared once if we set REgister F8h cfgAtve (both USB2 and USB3 hub found ), but we couldn't find any TI doc to say cfgActive is needed to do.

    Could you please advise the reason why it can fix to help us to check the root cause?

    BR,

    Colin 

  • +1 in reply to Colin Liu
    TI__Guru*** 145435 points

    if SMBUS is low, hub is in SMBUS mode. you need to set register F8h cfgAtve.

    Best

    Brian