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SN65DP159: When input 4k60 RGB444 video signal,there is no display on SN65DP159 EVB.

lifang lu
Intellectual 320 points

Part Number: SN65DP159
Other Parts Discussed in Thread: DP159RGZEVM

Hi TI,

When input 4k60 RGB444 video signal,there is no display on SN65DP159 EVB.

We wanna know if SN65DP159 can support 4k60 RGB444?

And how to configurate the EVB?Below is current configuration:

  • 0
    TI__Guru**** 183811 points

    Hi,

    What is the source? Is this a DC-coupled HDMI or AC-coupled DP++?

    Thanks

    David

  • 0 in reply to David (ASIC) Liu
    Intellectual 320 points

    Hi David，

    The source is AC-coupled TMDS.

  • 0 in reply to lifang lu
    TI__Guru**** 183811 points

    Hi,

    Are you using the RGZ or the RSB EVM?

    • Does HDMI1.4 work?
    • If you unplug/plug the cable again, are you able to see the video?
    • Do you see the LED D2 lights up when you plugging in the cable? 
    • Does HPD_SNK go high when HDMI cable is plugged into the EVM?
    • For RGZ, can you pop R126, R125, R132, R133, and de-populate R31, R32 for DDC snoop only?
    • For RSB, can you pop R126, R136, R140, R141, and de-populate R31, R32 for DDC snoop only?

    Thanks

    David

  • 0 in reply to David (ASIC) Liu
    Intellectual 320 points

    Hi David，

    Our EVM is DP159RGZEVM.

    1. HDMI 1.4 is normal

    2. If you unplug/plug the cable again, are you able to see the video?-------------- It doesn't work

    So DP159 does support 4k60 RGB444 and current configuration is correct,right?

    You guess that there is a problem with the EKM's hardware configuration?What's the difference between these below conditions?

  • 0 in reply to lifang lu
    TI__Guru**** 183811 points

    Hi, 

    DP159 will support 4k60 RGB444 resolution.

    HDMI1.4 is normal -> Are you using the same source or a different source?

    To accommodate systems that do not properly support clock stretching on the DDC lines, we have implemented a snoop mode on the DP159RGZEVM. This mode allows the DDC lines to be routed around the DP159RGZ, but remain connected to the DP159RGZ on the sink side to allow the DP159RGZ to snoop the DDC traffic. This snoop mode is enabled by default on the DP159RGZ REV B1 EVMs. Please note that when using the snoop mode, the source may require a 3.3V DDC while the HDMI is a 5V DDC, so you may need a level shifter between the 3.3V DDC and the 5V DDC.

    Thanks

    David

  • 0 in reply to David (ASIC) Liu
    Intellectual 320 points

    Hi David,

    We have tried thru HDMI DDC snoop mode and HDMI2.0 video can display normally.

    But I find a related question on

    However, the result is the opposite.

    So we are confused ,if we need to use the snoop mode when HDMI2.0?

  • 0 in reply to lifang lu
    TI__Guru**** 183811 points

    Hi, 

    Good to hear that you got the HDMI2.0 video working.

    That particular e2e thread does not have a full answer so I am not sure the DDC snooping is part of their problem. Like the thread said, it could be an I2C timing issue.

    The snoop mode is a separate issue from the HDMI2.0. The DP159  implements clock stretching, but not all sources implement clock stretching. When using the DP159 with a source that does not support clock stretching, then this would cause the DDC bus to hang. So the DDC snoop mode is recommended when working with a host that does not support clock stretching.

    Thanks

    David