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TPS65987D: DisplayPort Alternate Mode do not work

Part Number: TPS65987D
Other Parts Discussed in Thread: TUSB1046EVM, USB-C-PD-DUO-EVM, , TPS55288, TIDA-050014, 10G-EXPANSION-EVM

Hello TI Team

I'm trying to use evaluation boards(USB-C-PD-DUO-EVM and TUSB1046EVM) to project images on a DP alternate mode compatible display.

The Applicaiton Report(SLVA844B, p15) said that the DFP sends a Enter Mode command message.

https://www.ti.com/lit/an/slva844b/slva844b.pdf?ts=1685672317859&ref_url=https%253A%252F%252Fwww.google.com%252F

However I got PD log, it was found that DFP(TPS65987D) didn't send Enter Mode command message.

Do you know what causes Alternate Mode to not work properly? Or is there anything else I should check?

As a PD log of successful alternate mode, the laptop communication was also captured and compared.

Capture left:USB-C-PD-DUO-EVM+TUSB1046EVM+Display

Capture right:laptopPC+Display(DP Alternate Mode success)

I used the sink side board of the USB-C-PD-DUO-EVM. Attached is the project I wrote.

Referring to Application Report (SLVA844B) , the following four locations were set.

①0x38, Alternate Mode entry sequence
②0x47, TX identity data objects
③0x51, DisplayPort capabilities
④0x5C, GPIO event map

GPIO3  of USB-C-PD-DUO-EVM is connected to TUSB1046EVM as HPD.

GPIO14  of USB-C-PD-DUO-EVM is connected to TUSB1046EVM as FLIP.

(of cource I know that the push button S202,USB-C-PD-DUO-EVM will not work.)

230524USB-C-DUO-EVMsink_TPS55288.pjt

 

Sincerely,

Anna

  • Hi Anna,

    The USB-C-PD-DUO-EVM is meant for power only and do not support other functions due to EVM design.

    You will need to use the actual TPS65987D EVM to do implement the DisplayPort functionality.

    Regards

  • Hi Tommy

    Thank you for your reply.

    I have two additional questions.

    (1) Will the attached project (based on [TIDA-050014 Sink Board] with Alternate Mode) work fine when written to the actual TPS65987DEVM?

    If there is an any problem, which of the GUI options should I use as the base project?

    (2) You said that "do not support other functions due to EVM design", what exactly are the limitations?

    And are these limitations due to the electrical circuit or the software project?

    I would like to know if this is related to why DFP (TPS65987D) does not send out an Enter Mode command message. 

    Sincerely, 

    Anna

  • Hi Tommy,

    This inquiry comes from my customer. 

    How they can evaluate Alternate Mode functionality using TPS65987DEVM or other PD controller? 10G-EXPANSION-EVM is already obsolete and not supported anymore.

    Best regards,

    Shota Mago

  • Hi,

    The 10G-EXPANSION-EVM is for the DP data to pass through. You can still evaluate the alternate mode messages without this.

    Regards

  • Hi,

    For (1), you will want to use the Advanced template to create a project that support alternate mode.

    For (2), the PWR DUO Sink board will not work due to electrical design.

    Please create a project using the Advanced template and collect the PD log if it does not work so I can analyze the issue.

    Regards

  • Hi Tommy
    Thank you for your reply.

    If you know the details, please let me know.
    >For (2), the PWR DUO Sink board will not work due to electrical design.

    I have pulled the wires from GPIO3 (HPD) and GPIO14 on the PWR DUO Sink board and connected them to the TUSB1046EVM.
    But you are saying that the DFP(TPS65987D) uses other signal lines, SBU, SSTX and SSRX, to send an Enter Mode command message?

    Sincerely,
    Anna

  • Hi,

    The Sink board does not have VCONN capability and in alternate mode if TPS65987D is a DFP it will need to supply VCONN.

    Enter mode message is send through CC line. 

    Regards

  • Hi Tommy

    Thank you very much for the useful information.
    As a matter of urgency, I connected LDO_3V3_SINK to PP_CABLE (pin 25), which is the power source of VCONN, and was able to confirm the Alternate Mode sequence successfully all the way through. (According to the datasheet, I really wanted to supply 5V and set a bypass capacitor.)

    By the way, I understood that the PWR DUO Sink board doesn't pass through image signals because the signal lines SBU, SSTX, and SSRX through which DisplayPort signals pass are not connected.

    Thank you very much for your help.

    Sincerely,
    Anna

  • Hi Anna,

    Glad the issue is solved. Please do not hesitate to open another thread if you encounter other issues.

    Regards