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AM5718: HDMI Hardware issue

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Replies: 33

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Part Number: AM5718

Hello All;

We have designed our custom board in which we have used the AM5718 Processor. During the testing we found "omapdss error: HDMI I2C timeout reading EDID" error.


Please check the below image of HDMI connection of our board. we have doubts on hardware so can check and guide us if any hardware issue?

Thanks & Best Regards;

Nikunj Patel

  • Hi,

    Do you have a display connected on the HDMI? Have you checked the signal levels on the HDMICONN_I2C signals?

     

    Best Regards
    Biser
  • In reply to Biser Gatchev-XID:

    Hi Biser;

    We check during the power on/off the boot but there was no any signal on those pins.
    can you help me for how to check the signal?
    Have you check our HDMI connection? is it ok?


    Thanks & Best Regards;
    Nikunj Patel
  • In reply to Nikunj Patel:

    Please answer my questions above:

    Do you have a display connected on the HDMI? Have you checked the signal levels on the HDMICONN_I2C signals?

     

    Best Regards
    Biser
  • In reply to Biser Gatchev-XID:

    Hi Biser.

    Do you have a display connected on the HDMI?
    Ans:Yes

    Have you checked the signal levels on the HDMICONN_I2C signals?
    Ans: There was no any signal on both pins [we measured at R795 and R796]

    Thanks

  • In reply to Nikunj Patel:

    Hi Biser,

    gentle reminder.

    Thanks & Best Regards,

    Nikunj Patel

  • In reply to Nikunj Patel:

    Hi Nikunj,

    Sorry for the delay, this has been discussed internally. Please refer to the AM572x GP EVM schematic: www.ti.com/.../tidria3 The HDMI schematic is on page 17 of the Processor Module board. Note that all pullup/pulldown resistors marked as DNI should be removed.

     

    Best Regards
    Biser
  • In reply to Biser Gatchev-XID:

    Hi Biser,

    We checked the page 17 of " www.ti.com/.../tidria3 " schematic but this schematic does not match with our configuaration.

    We have taken the reference of "www.ti.com/.../sprr242.pdf" Am5718 idk's Schematic for our board and We does not populate R556,R563,R804,R805,R562,R560 resistor on our board.

    can you one more help to provide us the full log of HDMI log with AM5718 idk board?

    Thanks & Best Regards;
    Nikunj Patel
  • In reply to Nikunj Patel:

    This is the request I got from the factory team:

    "They need to capture the signal levels when the communication first starts. I assume that the Hot Plug Detect is used to trigger a query over the I2C bus. This initial query (and possible response) is what they need to capture on a scope for analysis. They need to clearly indicate on the scope where 0V is located and to then determine whether the I2C signals are going low enough to indicate a low level."

     

    Best Regards
    Biser
  • In reply to Biser Gatchev-XID:

    Hi Biser;

    We have checked the "HDMI_DDC_SCL" pin at R795 resistor. When we plug the HDMI Cable to the board this signal goes to low. as per attched images.

    1)  When HDMI Cable Plugged

    2)  When HDMI Cable UnPlugged

    Thanks & Best Regards;

    Nikunj Patel

  • In reply to Nikunj Patel:

    Nikunj,

    The SCL pin should not go low and stay low.  This is invalid for I2C to function.  There must be a design or assembly issue causing this condition.  How many boards have you assembled?  Do they all behave the same?  Do you have a different HDMI display that you can plug in to see if the behavior is different?  Another test would be to use an AM571x IDK with the HDMI panel and to probe the signals to see what is different.

    Tom

     

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