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TPS65982: Behavior of AutomaticIDRequest(0x29 bit24)

Part Number: TPS65982

Hi Team,

My customer would like to know how AutomaticIDRequest  bit behaves and I need to explain that function to them.
Please help me to understand the behavior of this bit.

From the explanation in Host interface guide, I understood a Behavior of AutomaticIDRequest as below.

[My understanding of AutomaticIDRequest  bit behavior]
If this bit is set to "0", TPS65982 never issues Discover Identity command as Initiator when it’s working as DFP.
Therefore, EC needs to issue Discover Identity by 4cc command at Cable plug and DP alt process.

Then I I have 4 questions as followings.
1. Is my understanding above correct?

2. What is a difference between AutomaticIDRequest and AMIntrusiveMode?

3. How does the TPS65982 behave for the following commands when AutomaticIDRequest is set to "0"?
- Discover SVIDs
- Discover Modes
- Enter Mode
- Exit Mode
- Attention

4. Does TPS65982 automatically respond for all received VDM commands when it's in UFP and AutomaticIDRequest is set to "0"?

Regards,

Takashi Onawa

  • Hi Onawa-san,

    1. Your understanding is correct.

    2. When AutomaticIDRequest is enabled, the PD controller will automatically send the Discover Identities message when appropriate. When AMIntrusiveMode is enabled, the PD will not automatically send any Alternate Mode communication over the CC lines and the EC is expected to send the Alternate Mode messages through 4CC Commands. I do not recommend to enable AMIntrusiveMode as it relies heavily on the EC sending the correct messages when entering Alternate Modes.

    3. The TPS65982 will not automatically send the Discover SVIDs or Discover Modes messages when AutomaticIDRequest is set to 0. It will not attempt to negotiate any alternate modes until the host tells it to send a Discover SVIDs or Discover Modes message. The enter mode, exit mode, and attention messages are not affected by the AutomaticIDRequest bit.

    4. TPS65982 will still automatically respond to all received VDMs with AutomaticIDRequest set to 0. with AutomaticIDRequest set to 0, it will not automatically send VDMs but it will still respond to received VDMs. This is only true when AMIntrusiveMode is disabled.

    Thank you,
    Eric
  • Hi Eric-san,

    Thanks, I could almost understand how the function behaves. Let me ask one question before closing.

    What is the concept of this function?
    In other word, What kind of applications and situations should the AutomaticIDRequest be disabled in?

    Regards,
    Takashi Onawa
  • Hi Onawa-san,

    You could disable AutomaticIDRequest if you do not want to automatically begin negotiating alternate modes. Maybe you only want to negotiate alternate modes under certain conditions determined by the EC. Disabling AutomaticIDRequest will allow the user to control when they start negotiating alternate modes. Otherwise the TPS65982 will always automatically attempt to negotiate alternate modes.

    Thank you,
    Eric
  • Hi Eric-san,

    Does AutomaticIDRequest bit only affect to commands for Alt mode negotiate process?
    The Discover Identity command is not used only in Alt mode negotiate process but also for E-marker communication.

    If the customer would like to communicate E-marker IC in AutomaticIDRequest OFF condition, Does the EC also has to send Discover Identity VDM for Cable communication by 4cc command?
    If yes, when the command should be issued?

    Regards,
    Takashi Onawa
  • Hi Onawa-san,

    disabling AutomaticIDRequest will not affect the communication to the E-marker that takes place directly after a connection. The PD controller will still communicate to the E-marker even with AutomaticIDRequest disabled.
    AutomaticIDRequest should only relate to the Discover Identities command for Alternate modes.

    Thank you,
    Eric
  • Hi Eric-san,

    Thanks. I understood.

    Regards,
    Takashi Onawa
  • Hi Eric,

    How to disable AutomaticIDRequest by FW setting?

    Thanks


  • Hi Daniel,

    To disable Automatic ID Request, simply un-check the box next to Automatic ID Request in your screenshot.

    Thank you,
    Eric
  • Hi Eric,

    Many thanks, I did not notice the box.

    We face another issue about the Automatic ID Request and MacBookPro compatibility, please kindly give us some suggestions. Thanks.

    FW Tool : TPS6598x Application Customization Tool version 3.10

    Application : Monitor

    Issue : When  "Automatic ID Request" is enable, following MacBookPro issue is happened.

    1. Monitor power ON, MacBookPro power OFF.

    2. Connect Monitor and MacBookPro by USB-C cable.

    3. Power ON MacBookPro.

    4. Displayport is no problem. But USB HUB is not working.

    Root cause : When the issue is duplicated, the roles of monitor are DFP_U/UFP_D/Source.

    *Monitor must become UFP_U to use USB HUB.

    Detail of PD Negotiation---(a)

    1. At connected, monitor is DFP_U/Source.

    2. After PS_RDY, monitor send DR_SWP.

    3. MacBookPro reject DR_SWP.

    4. Monitor send Discover Identity.(Start Alternate Mode)

    5. Finally, monitor become DFP_U/UFP_D/Source.

    *PA271Q should re-send DR_SWP message.

     

    After "Automatic ID Request" set to disable

    Detail of PD Negotiation---(b)

    1. At connected, monitor is DFP_U/Source.

    2. After PS_RDY, monitor send DR_SWP.

    3. MacBookPro reject DR_SWP.

    4. After about 400ms, monitor re-send DR_SWP and MacBookPro accept.

        In this time, monitor become UFP_U/Source.

    5. MacBookPro send Discover Identity.(Start Alternate Mode)

    6. Finally, monitor become UFP_U/UFP_D/Source. And USB HUB can work.

    If "Automatic ID Request" should be enabled to pass the compliance test, any other way to re-send DR_SWP?

    Many Thanks

  • Hi Daniel,

    This is a very old thread. Can you please open a new thread with this new question? It would better help us respond to your faster.

    Thank you,
    Eric