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TUSB320LAI: tusb320lai detection device

Sammi Shang
Expert 4450 points
Part Number: TUSB320LAI
Other Parts Discussed in Thread: TUSB320

Dear team,

Customer has a question about the device detection of TUSB320LAI. Please confirm if we think right: for customer end equipment, the adapter should be as DFP role. The computer could be DRP role. Then TUSB320 should send try.src commend to confirm the role of computer.

Was my thought right? The issue customer met is that they find both computer and adapter show as DFP role, they could not clarify those two devices.

Thanks.

Best regards,

Sammi

  • 0
    TI__Guru 64326 points

    Hi Sammi,

    A DFP to DFP configuration is not valid configuration. How did customer confirm that both show as DFP? Even if TUSB320LAI is set for Try.SRC once connected to a DFP, TUSB320LAI should become a UFP. 

  • 0 in reply to Malik Barton57
    TI__Expert 4450 points

    Hi Barton,

    Thanks for your reply. I think maybe you misunderstanding my meaning.

    When connect adapter, adapter is UFP, TUSB320 is DFP;

    When connect computer, computer may be DRP, the USB320 is also DRP.

    How should TUSB320 tell which kind of device? Through CC pin waveforms?

    Thanks.

    Best regards,

    Sammi

  • 0 in reply to Sammi Shang
    TI__Guru 64326 points

    Hi Sammi,

    TUSB320 detects device role over CC line. Can you measure CC pin to see what is happening when connector or conmputer is connected? After the PORT pin changes state is there a reset to TUSB320?

  • 0 in reply to Malik Barton57
    TI__Expert 4450 points

    Hi Barton,

    We measure the CC pin waveforms when connect with adapter and computer. When connect with those two device, CC2 has no signal, Vcc1 for adapter is nearly 500mV, and Vcc1 for computer is nearly 350mV. Both meet the voltage level of UFP in datasheet page 5.

    Customer want to know if there is a flag or mark that could help clarify adapter and computer. When connect USB flash drive, register 0x09 attached_status shows '01', when connect headset, attached_status shows '11', but when connect adapter and computer, attached_status both shows'10'. But customer need to identify the device if it is computer, because they need to send data so need to add demand.

    They let the PORT pin NC so that 320 could work as a DRP.

    Thanks.

    Best regards,

    Sammi

  • 0 in reply to Sammi Shang
    TI__Guru 64326 points

    Hi Sammi,

    There is only a flag for Debug and accessory connection through I2C not GPIO. For Debug accesory it would be Rd on both CC pins. Since a cable is used in this test scenario there is no way for TUSB320LAI to set Debug accessory flag. This adapter+computer scenario seems to only present Rp so even if TUSB320LAI does try.src it will connect as UFP. This constant Rp is most likely caused by the adapter. I assume the adapter is Type-A to Type-C so Rp is hard wired on both CC pins. What kind of data needs to be sent?

  • 0 in reply to Malik Barton57
    TI__Guru 64326 points

    Hi Sammi,

    Is there any more support needed for this issue? If so please reply with any relevant details so that I can further assist you. For now I will be marking this thread as "TI Thinks Resolved". If you have resolved your issue, please post the solution to the original problem/post for others with similar issues.