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TPS65986EVM: Board with will not enable USB 3.1g1 data

Alec Bowman
Prodigy 30 points
Part Number: TPS65986EVM
Other Parts Discussed in Thread: DP-EXPANSION-EVM, HD3SS460

I have been unable to get USB 3.1g1 data flow using the TPS65986EVM with the DP-EXPANSION-EVM in the client configuration.  In fact, in most cases, I can't even get a USB 2.0 data flow.  The only time I can get 2.0 data is if a 4 lane display port contract is established between the host and client.  For my application, I do not need or want alternate modes enabled, but I do need 3.1g1 data throughput.  I have tried using the stock firmware on the board in addition to custom firmware.  None of these have produced the desired data throughput.

I have seen this question arise multiple times on this forum (links below), however, none of these posts were ever resolved from the data standpoint.  Please advise me on steps I could try.  

https://e2e.ti.com/support/interface/usb/f/1008/t/608928?tisearch=e2e-sitesearch&keymatch=dp-expansion-evm

https://e2e.ti.com/support/interface/usb/f/1008/t/533080 

  • 0
    TI__Mastermind 36756 points
    Hi Alec,

    The HD3SS460 is a Display-Port Alternate Mode MUX that is controlled by GPIOs of the TPS65986. This MUX is only enabled once DisplayPort Alternate Mode has been entered.

    Thank you,
    Eric
  • 0 in reply to Eric Beljaars
    Prodigy 30 points
    I have been probing these GPIO pins to check their state and have even changed the behavior of the GPIO pins to try to force the AMSEL and EN pins to the appropriate level. Still no success. Additionally, this would not fully explain the loss of low speed data as these signals are not pass through the HD3SS460.

    Note also that the default templates in the TPS6598x Application Customization Tool (specifically the template "TPS65986_HD3SS460_UFP_Standard_3_07.tpl") has the plug event on GPIO 3 and the AMSEL event on GPIO 0, even though the board is wired the other way around. I've tried it in both arrangements. Still no success.
  • 0 in reply to Alec Bowman
    TI__Intellectual 1990 points

    The behavior you are seeing is probably expected for the following reasons:

    1. If Alternate mode is not entered, the billboard end point in TPS65986 would be enumerated.  Therefore no USB2 connection.  In this case, you should see TPS6598x end point enumerated under USB2.0 hub in device manager.

    2. If Alternate mode is entered with pin assignment C, only USB2 would work.  If alternate mode is entered with pin assignment D, USB3 should work but due to extra connectors in the path(including samtec expansion connector), the attached USB device may not enumerate in USB3 but only in USB2 depending on the signal integrity of the overall connection from the USB3 host controller to the connected USB3 device. 

    These are the EVM setup specific issues.  In typical applications, the USB2 path for the billboard is connected behind a hub downstream port while the exposed USB connectors through other downstream ports of the hub therefore these issues should not occur unless SI is bad, which is also typically improved with signal conditioning in USB systems.