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TMDS181RGZEVM: Sometime the output of EVB is unstable

kenick kim
Prodigy 140 points
Part Number: TMDS181RGZEVM
Other Parts Discussed in Thread: TMDS181

Hello,

We have found some strange behaviour with TMDS181RGZEVM.

Our test configuration is like below.

Source -> EVB -> TV

When we unplug and plug HDMI cable repeatedly,

Sometime we can see video flicker or no connection on TV even if the input status is normal.

On this situation normally it is solved if we set the apply_RXTX_changes register in the TMDS181. But not 100%.

It doesn't happen when we test without the EVB.

Your support will be very appreciated.

Thanks

Kenick

  • 0
    TI__Expert 5455 points
    Hello Kenick


    Could you share more details regarding the configuration of EVM? When you reconnect the sink, is it not detected (sometimes)? If you set apply_rxtx_changes, can you share the values of TX_TERM, HDMI_TWPST1 and the other registers? Are you using I2C configuration?


    Regards
    Francisco
  • 0 in reply to Francisco Javier Zamudio
    Prodigy 140 points

    Hello Francisco,

    Thank you for your reply.

    Please refer to below configuration.

    This case is when TV doesn't detect input signal.

    It occurs too when we set and reset HPDSNK_GATE_EN repeatedly.

    Please let us know if you need more input.

    Thanks

    Kenick

  • 0 in reply to kenick kim
    Prodigy 140 points
    Hello Francisco,

    Belows are answers for your question.
    TX_TERM = 00, HDMI_TWPST1 = 00, use I2C configuration.

    Thanks

    Kenick
  • 0 in reply to kenick kim
    TI__Expert 5455 points
    Hello Kenick

    HPDSNK must be unchecked because this signal is necessary. Can you describe in more detail the video flicker?
    Please, follow the quick start guide to test the sink:
    1. Apply 5-V power to the EVM, turn on SW2.
    2. If using external I
    2C configuration instead of pin straps, configure the TMDS181 at this step.
    3. Plug in an HDMI source using a standard HDMI cable into P1 (Standard HDMI connector). LED D2
    should light up.
    4. Plug in an HDMI video sink device into P2 (Standard HDMI connector) using a standard HDMI cable.
    5. Video output on HDMI sink should be observed.

    Can you send me an example of your issue? something like a screen shot or a small video?


    Regards
    Francisco
  • 0 in reply to Francisco Javier Zamudio
    Prodigy 140 points

    Hello Francisco,

    We've got two knid of phenomenon. One is the video fliker that look like white noise pattern. I will take a picture of it when I have it again.

    Another is "no input" message on TV(SinK side) even if source is connected to the EVB.

    It occurs on situtation as below

    1. Turn off and on a TV(a HDMI sink device) repeatedely. (Source, EVB, Sink are connected with HDMI cables and turned on situation)

    2. Unplug and plug the HDMI cable into P2.

    3. Reset and set Apply_RXTX_Changes. (Source, EVB, Sink are connected with HDMI cables and turned on situation)

    Actually we want to use TMDS181 in the middile between a source and a sink.

    So we have to clear these kind of issues. Please help us.. Thanks

  • 0 in reply to kenick kim
    TI__Expert 5455 points
    Hello Kenick

    I think that I would need more information about your issue because I have the same EVM here and I can't see anything like you. I also connected and disconnected the source and sink, and I don't have any problem. Did you follow the instructions that I sent you in the last post? Are you sure that your sink is inside of the data rate of the TMDS? Please, perform a double check on it and also check the users guide www.ti.com/.../sllu228a.pdf.
    Also please, clarify your application, do you want it to us as redriver, retimer, snoop?

    Regards
    Francisco
  • 0 in reply to Francisco Javier Zamudio
    Prodigy 140 points
    Hello,

    Thank you for your reply.
    I also followed the instructions in your post and we use the retimer mode.
    Actually our sources are setop boxes and sinks are monitors. I found that it just happen with the specific source or sink.
    With some source and sink we aslo have no problem at all.
    In fact that the specific source and sink which made problems work good if we didn't put the EVB in the middle.That is our problem.

    For our application it has to be OK with all kind of source and sink.
    How we can make it clear.
    Please let us know if you need more information or test. I will stay in our lab more. So I can give you more information today.
    You support will be very appreciated.

    Thanks

    Kenick
  • 0 in reply to kenick kim
    TI__Expert 5455 points
    Hello Kenick

    First of all, we have to clarify the characteristics of source and sink. Would be useful to have the information of the specific source and sink which you have a problem and you mentioned. I'll give you an example why is necessary to know this information, if you have a source/sink that works with 4 K (4096x2160), refresh rate = 60, color bit depth = 8 and chroma sampling = 4:4:4 you will have a data rate for each lane = 5.94 Gbps and our device working in HDMI 2.0 can supports up to 6 Gbps, then is inside of the Data Rate and you won't have any problem, but if you changed a little bit the parameters of the source/sink, for example, you change the color bit depth from 8 to 10, now you will have 7.42 Gbps and our device won't handle this data rate.
    Your application can be able to support all sources and sinks that are inside of the parameters of our device, if not, unfortunately, you'll can't use it.
    The necessary information is the data rate that you need in your set up, if you confirm that this is inside of the parameters of the TMDS181, then please send pictures of your set up and the video flicker. Also, please send the length of cables that you are using and jumpers connection. If you are using the eyescan, J6 and J4 have to be connected to SDA/SCL_USB.

    Regards
    Francisco