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HD3SS3220: HD3SS3220 Link bring up Test TD7.01.2 problem

Manuel Zabee
Prodigy 10 points
Part Number: HD3SS3220

Tool/software:

Dear TI,

currently we made pre compliance USB tests at Granit River Labs. We use the Microchip Hub USB5708C and the TI MUX HD3SS3220 for the upstream facing port with USB Type C connector. The downstream facing ports are all USB Type A connectors.

Here we got a fail at the test for the upstream facing port.

TD7.01.2 Link Bring-up Test (Subtest 2): The PUT has transmitted more than 6 LFPS after receiving 1 LFPS while the Number of LFPS tx´d before receiving 1 > 18 - the Numer of LFPS tx´d after receiving 1. Gen 1 links should not do this to prevent conflicts with Gen 2 LFPS handshaking.

The downstream facing ports without the mux are working fine.

First i opened a case by microchip. But here finally i got this answer:

You also stated downstream ports are passing this test. Its the same PHY and behavior. the USB3 PHYs don't have any difference whether they are upstream or downstream. So that gives a strong clue that the mux is involved. What does TI say on the matter? I would recommend the customer also open a case to see if this is a known failure.

Do you know this issue with the mux?
Do you have a suggestion to fix this?

Attached is the schematic for the mux and the failure description.

Regards,
Manuel

  • 0
    TI__Mastermind 37690 points

    Hi Manuel,

    Manuel Zabee said:

    Attached is the schematic for the mux and the failure description.

    Looking at the schematic you sent over, I see that it looks like the CC pins are flipped, I.E CC1 of the 3220 is going to CC2 of the connector, and CC2 of the 3220 is going to CC1 of the connector. Is this intended? This might be affecting the flip orientation of the HD3SS3220.

    Does the HD3SS3220 enumerate properly, I.E USB3 enumerating over the type-C connection? I want to ensure the device with the HD3SS3220 is able to properly communicate over the connection.

    Manuel Zabee said:
    Do you know this issue with the mux?
    Do you have a suggestion to fix this?

    This is not a known issue with our device, so I don't believe it is related to our device. Our mux also should not directly affect any of the data that is passed through, as it is just a typical passive mux. 

    Thanks,

    Ryan

  • 0 in reply to Ryan Kitto
    Prodigy 10 points

    Hi Ryan,

    thanks for you answer.

    First i connected the CC1 to the CC1 of the Type C connector, but then it doesn´t work correctly... After I switched it to CC2 it was fine. It works like expected.

    So the mux has no special USB modes or can shortly disconnect the connection between the input and output (except when disabled or the CC pins are switched)?

    Regards,
    Manuel

  • 0 in reply to Manuel Zabee
    TI__Mastermind 37690 points

    Hi Manuel,

    Manuel Zabee said:
    So the mux has no special USB modes or can shortly disconnect the connection between the input and output (except when disabled or the CC pins are switched)?

    Yes, correct. The HD3SS3220 does not have any special modes outside of active and shutdown, both of which are controlled by the EN pins.

    Manuel Zabee said:
    First i connected the CC1 to the CC1 of the Type C connector, but then it doesn´t work correctly... After I switched it to CC2 it was fine. It works like expected.

    Looking at the TX/RX pins in the schematic again, it does look like it is swapped, I.E TX1 of the HD3SS3220 goes to TX2 of the Type-C connector. That would explain why you had to swap the CC pins.

    Thanks,

    Ryan