This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

  • Resolved

AM5718: HDMI Hardware issue

Expert 1760 points

Replies: 33

Views: 1614

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

  • In reply to Tom Johnson 16214:

    Hi Tom;

    Thanks for your quick reply.

    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?

    Ans: We have checked with the 3 different boards and 3 different HDMI Display and all have the same issue.

    Another test would be to use an AM571x IDK with the HDMI panel and to probe the signals to see what is different.

    Ans: We does not have the AM571x IDK board so we can't measure this SCL pin. can you help us to probe the signals if you have AM571x IDK Board?

    Thanks & Best Regards;

    Nikunj Patel

  • In reply to Nikunj Patel:

    Nikunj,

    Sorry, I clicked the wrong button.  I did not mean to indicate that the question is answered.

    Tom

     

  • In reply to Tom Johnson 16214:

    Nikunj,

    We know that the IDK works.  SCL being held low is an invalid I2C bus condition.  It blocks all communication.  The point of having you probe the IDK was not to see if the SCL was held low.  It was for you to measure the various signals around the TPD12S016 to determine what is different in the various operating states.  I recommend that you acquire one for this purpose.

    Your HDMI schematic implementation is slightly different from the one on the IDK.  Have you cross-checked the differences to make sure that they meet your requirements and software driver?  Can you modify the connections on one of your boards to make it match the IDK implementation to see if that enabled success?

    Tom

     

  • In reply to Tom Johnson 16214:

    Nikunj,

    I see that you had a previous E2E open on this topic at: 

    .  What was the resolution on the I2C in that thread?  You mentioned that you had functional communication in standard I2C pinmux mode.  I see that you asked about the pin definitions being reversed between standard I2C and HDMI I2C.  This reversal is known and it is true.  Do you have this connected incorrectly on your board for HDMI I2C use?

    Tom

     

  • In reply to Tom Johnson 16214:

    Hi Tom;

    Your HDMI schematic implementation is slightly different from the one on the IDK.  Have you cross-checked the differences to make sure that they meet your requirements and software driver?  Can you modify the connections on one of your boards to make it match the IDK implementation to see if that enabled success?

    Answer: yes there was only one Change of gpio control differ from IDK. but we already change software configuration for that and we measured voltage and it was proper 3.29 volt. Also as per your suggestions I will check with removing gpio connection and change the R559 to 0 ohms.

    What was the resolution on the I2C in that thread?  You mentioned that you had functional communication in standard I2C pinmux mode.  I see that you asked about the pin definitions being reversed between standard I2C and HDMI I2C.  This reversal is known and it is true.  Do you have this connected incorrectly on your board for HDMI I2C use?

    Ans: we have correct connection on our board.

    You can check the image of HDMI connection's schematic which was post by me on staring of this thread.

    Thanks & Best regards;

    Nikunj Patel

  • In reply to Nikunj Patel:

    Nikunj,

    In the other post, you show scope images of I2C data transfers.  What is different from then?  Now you are reporting that the SCL net is held low as soon as the HDMI is plugged in.

    Do you know which side is holding it low?  Can you provide the picture shown above for both the connector side and the processor side?

    Tom

     

  • In reply to Tom Johnson 16214:

    Hi Tom,

    We have configured HDMI_DDC_SCL as normal I2C_SDA and HDMI_DDC_SDA as normal I2C_SCL mode using spl-uboot pin MUX configuration only for damage or proper soldering of pin checking as per describe in other post.

    Thanks & Best regards;

    Nikunj Patel

  • In reply to Nikunj Patel:

    Nikunj,

    But how does that work with the pins swapped?

    Tom

     

  • In reply to Tom Johnson 16214:

    Hi Tom;
    I am not saying that the HDMI-DDC-I2C is working.
    We test only these two pins using "i2cdetect" linux utility. During the utility run we have measured signals and we found signal as per previous post.

    Thanks & Best regards,
    Nikunj Patel
  • In reply to Nikunj Patel:

    Nikunj,

    Were you able to communicate with an HDMI display while in the Linux I2C mode?  Or were these captures made while there was no display attached?

    Tom

     

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.