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SN65DSI86EVM: Link training failure when using DP to HDMI cable

John Basista29
Prodigy 60 points
Part Number: SN65DSI86EVM
Other Parts Discussed in Thread: SN65DSI86

Hi,

I am currently using a SN65DSI86EVM board to evaluate using this DSI to DP converter IC for use driving an embedded LCD screen.  Currently, I am using a LCD driver board with an HDMI input for initial prototype testing, but intending to drive the LCD directly from the SN65DSI86 IC in the future.

I am trying to get the DP output to display the color bars from the IC to test the DP output, and then will be working to solve my DSI input configuration if there is any issues.  I am getting LT_FAIL flag in register 0xF8 (value is 0x02), but am unable to figure out why that is happening.  I have used the example from the EVM user guide, as well as going through the scripts posted here (e2e.ti.com/.../2062378) to try to configure the output, but no avail at all.

Any help with debugging this would be appreciated.

Regards,

John Basista

  • 0
    TI__Mastermind 18655 points

    Hello John,

    We will be glad to help with your implementation. Please, share the eDP panel's EDID. Normally, it is available in the panel's datasheet. You can get the EDID using the SN65DSI86. Take a look at the attached scripts for reading these registers.

    4263.DSI86_SW_EXAMPLES.pdf

  • 0 in reply to Joel Jimenez0
    Prodigy 60 points
    Hi Joel,

    When using the instructions in the attached PDF, the DSI86 device does not respond to 7-bit address 0x50 (8-bit 0xA0), and is not writing any valid data out when reading (all 0xFF response).

    Could the issue be that I am not talking directly to the LCD panel, but trying to go through HDMI to a separate LCD driver board which communicates with the panel?

    Regards,

    John
  • 0 in reply to John Basista29
    TI__Mastermind 18655 points

    Hello John,

    Can you try the attached scripts?

    Read EDID using indirect method.zip

  • 0 in reply to Joel Jimenez0
    Prodigy 60 points
    Hi Joel,

    Using the IND_I2C_AUX_READ.xml file, I read the following values if following the script:
    ======Read AUX send bit======
    0x00 0x00 0x50 0x01 0x40
    ======Read Status======
    0x00 0x00 0x00 0x00
    ======Clear Status======
    ======Read Status======
    0xF9 0xFF 0xFF 0x83
    ======Read First 16 bytes MOT1 ======
    ======Read AUX send bit======
    0x00 0x00 0x50 0x10 0x50
    ======Read AUX_RDATA======
    0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
    ======Read Status======
    0xF9 0xFF 0xFF 0x83
    ======Clear Status======
    ======Read Status======
    0xF9 0xFF 0xFF 0x83
    ======Read 2nd 16 bytes MOT1 ======
    ======Read AUX send bit======
    0x00 0x00 0x50 0x10 0x50
    ======Read AUX_RDATA======
    0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
    ======Read Status======
    0xF9 0xFF 0xFF 0x83
    ======Clear Status======
    ======Read Status======
    0xF9 0xFF 0xFF 0x83
    ======Read Addr Only MOT0 ======
    ======Read AUX send bit======
    0x00 0x00 0x50 0x00 0x10
    ======Read Status======
    0xF9 0xFF 0xFF 0x83
    ======Clear Status======
    ======Read Status======
    0xF9 0xFF 0xFF 0x83

    Sorry if the formatting doesn't match, I am not using an aardvark to capture the data. This was also after a fresh power cycle of the system. Seems like it isn't reading anything on the AUX reads.

    Regards,
    John
  • 0 in reply to John Basista29
    Prodigy 60 points
    Hi Joel,

    I think I may have some understanding why this setup isn't working. The DP to HDMI cable is DP++ compliant, and it seems as though the sn65dsi86 device is not and cannot stream HDMI compliant signals in the same manner as a computer would. I am going to work on creating/getting an adapter for the EVM board to directly connect to the panel I am using in prototype development which should eliminate this problem. Once I do that, I will retry, as well as doing these troubleshooting steps if I have issues.

    Regards,
    John