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DP159 question

Peter Chen(ICP_FAE)
Intellectual 2480 points
Other Parts Discussed in Thread: DP159RGZEVM

How to configure the DP159RGZEVM board output HDMI if only AUX_P/N(there is no DDC clock and data from GPU ) output support in GPU? 

Does the I2C over AUX feature of DP159 need enable for this support?  

  • 0
    TI__Mastermind 23815 points
    Hi Peter,

    I²C over aux feature doesn't require an enable, just connect AUX channel to AUX_SRC.

    Regards
  • 0 in reply to Moises Garcia
    Prodigy 70 points

    Hi Moises:

    Let me explain our configuration and our request.

    In our module, the limitation of DDI0 channel is we didn’t connect DDC_CLK/DATA to ROW connector. We just have DDI0_AUXP/N to Row connector.

    So we want to use DP159 DP to HDMI ouput without DDC_CLK/DATA signal.

    We have DP159RGZEVM board with our module to test it.

    Unfortunately, we can't output HDMI screen until now.

    Below is our experiment configuration:

    Un-Pop:

    R127, R31, R32, R132, R133,

    POP:

    C2, C3

    I2C_EN: Low or NC

    HDMI_SEL: Low or NC

    Power: from power supply 5V

    SW2: 1-2

     

    Based on upon setting, the HDMI screen still can’t output.

    Please help us to clarify this issue.

    Please give us a right configuration in DP159RGZEVM board.

    Thx~

  • 0 in reply to Hsieh Neo
    TI__Mastermind 23815 points

    Hi Hsieh,

    AUX bridge is enabled by default, have you tested EVM with a different device like a computer to make sure the EVM is working?

    Regards

  • 0 in reply to Hsieh Neo
    Prodigy 70 points
    Hi Moises:
    Please refer to our history report, it recorded the deatil experiment information and our request.
    Thx~
  • 0 in reply to Hsieh Neo
    TI__Intellectual 2480 points

    Hello Moises,

    Quick question:

    The Neo wourl like to know that does DP159 support HDMI output without DDC(SDA_SRC/SCL_SRC).

    there is only AUX channel(No DDC) support in GPU. 

    There is no display problem if connect DDC and AUX with DP159EVM. The problem only happen if only connect with AUX channel only.

  • 0 in reply to Peter Chen(ICP_FAE)
    TI__Mastermind 23815 points

    Hi Peter,


    I got it, the GPU is unable to send I²C over AUX.

    Then the problem is not in DP159, you may use DP159 without DDC, just some controller will have to take care of TMDS_CLOCK_RATIO.

    The problem is: DP++ doesn't send video by default when DDC is not present, HDMI send video by default when DDC is not present.

    So, if there is no DDC Source will not send video to sink.

    Regards

  • 0 in reply to Moises Garcia
    Prodigy 70 points

    Hi Moises:

    Thank your help.

    I have three questions need your confirmation.

    1. So if there is no DDC Source support in the DP++ source end, the DP159 will not send video to sink.

    => It means the DP159 need DP dual mode, right?

    => DP159 can’t support only pure DP channel, right?

    2. DP++ doesn't send video by default when DDC is not present, HDMI send video by default when DDC is not present

    => It means if source is HDMI signal, it can output screen when DDC is not present, right?

    => DDC_CLK/DAT is not present, how can screen display correct pixel resolution?

    3. Based on our configuration, our DDI0 channel is pure DP, not DP dual mode(because no DDC_CLK/DATA), but we need to screen output HDMI device.
    Which chipset can recommend from TI?

    Thx~~


     

  • 0 in reply to Hsieh Neo
    TI__Intellectual 2480 points

    The DP159 support DP++ dual mode to HDMI only. It does not support pure DP input.

  • 0 in reply to Peter Chen(ICP_FAE)
    TI__Mastermind 23815 points

    Hi Hsie, Peter,

    First for Hsieh questions, let's clarify this DP/DP++ difference.

    DP is just the standard DisplayPort interface using 4 differential pairs for video and AUX channel for configuration.

    DP++ sends HDMI data using DP electrical signaling(AC coupled), that's why you need a level shifter from DP++ to HDMI.

    Presence or absence of DDC is not what differentiates from DP to DP++.

    Since you want HDMI output, you need DP++ with a level shifter. Another option could be a protocol converter from DP to HDMI(We don't have it)

    I mentioned DP++ needs DDC channel because we are talking about this application, but DP needs it AUX channel too.

    HDMI send video by default when DDC is not present, in this case source sends a default resolution it doesn't send the correct resolution.

    Although DP159 is advertised as DP++ to HDMI level shifter, it can be used as DP to DP retimer.

    If you are interested in this application, please refer to application note DP159 as DisplayPort retimer http://www.ti.com/lit/an/slla358/slla358.pdf

    Regards