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Original question:

TUSB321AI: Processing unused pins.

TUSB321AI: TUSB321AI in DRP mode is connected to another DRP

Yasushi Fujiwara
Genius 12725 points
Part Number: TUSB321AI

Hello Experts,

Would you please explain sequence to detect power role if TUSB321AI in DRP mode is connected to another DRP? Customer would like to know it. The state transition diagram is better to understand the sequence, if you have it.

Best Regards,
Fujiwara

  • 0
    TI__Guru*** 146295 points

    Fujiwara:

        TUSB321AI does not support power role swap, only support data role swap.

    Regards,

    Brian

  • 0 in reply to Brian Zhou
    TI__Genius 12725 points

    Hello Brian-san,

    TUSB321AI should support DRP as datasheet stated this function. I know this device doesn't support Try.SNK and Try.SRC, so I think that it will be race condition if TUSB321AI in DRP mode is connected to another DRP. But customer would like to know what is sequence to determine as a UFP in DRP mode or as a DFP in DRP mode.

    Best Regards,
    Fujiwara

  • +1 in reply to Yasushi Fujiwara
    TI__Guru*** 146295 points

    Fujiwara:

     RP devices will initially toggle their state between DFP (by connecting Rp and disconnecting Rd ) and UFP (by disconnecting Rp and connecting Rd ) operation, until the complimentary termination is found at the port partner on one of the CC lines.

    When two DRPs are connected together, they accept the resulting DFP-to-UFP relationship achieved randomly. Both DRPs toggle their states between DFP and UFP . Whenever a successful Rp – Rd voltage divider is formed on one of the CC lines, the connection is established.

    Regards,

    Brian