• State
  • Locked Locked
  • Replies 7 replies
  • Subscribers 35 subscribers
  • Views 662 views
  • Users 0 members are here
Support feedback
Options
Options
Related

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.

DS34RT5110 having good margin for HDMI tests but no image in playback

Ken Lim102090
Prodigy 40 points
Other Parts Discussed in Thread: DS34RT5110

Hi,

I am having no image issue during the playback using DS34RT5110 evaluation board,  I am configuring the DS34RT5110 as such:

BYPASS = low, EN = high, Mode = low, VOD_CRL = 24kohm to GND (DC coupled) .

I used a digital anayzer for the HDMI test (source clock jitter and eye pattern), the test result is really good having at least 50% margin. There is no image when connected to the monitor (SD and LOCK are high!) . I tried to bypass the Reclock and De-emphasis function (BYPASS = high), the image immediately appeared on the monitor. I can't really figure out what is the cause of it?

Can anyone here able to explain on this issue? Thanks.

 

  • 0
    TI__Genius 13475 points

    Ken - We offer a couple of different evaluation kits for the DS34RT5110 - Does your kit use just HDMI cables, or are there some RJ-45 connectors on the boards with ethernet cables?

    Describing the board(s) that you have will help me to figure out what you are looking at

    Also, do you have an oscilloscope available where you could look at the signals on the board.

     

  • 0
    TI__Expert 4400 points

    Please try setting the MODE pin high to disable the clock regeneration and see if this works in your application.

    If this does not work and you must set BYPASS high for proper operation, then perhaps the incoming jitter is exceeding the PLL / CDR bandwidth of the DS34RT5110.

  • 0 in reply to Mark Sauerwald88474
    Prodigy 40 points

    Hi Mark,

    I brought the DS34RT5110-EVKH, the kit have only HDMI connectors. I am using Tektronix DPO70804 digital analyzer to do the HDMI tests.

     

  • 0 in reply to Gary Melchior
    Prodigy 40 points

    Hi Gary,

    yes there is image when I set the MODE pin to high, but it failed the source clock jitter test.

    Is there a specification on the tolerance of the incoming jitter? 

  • 0 in reply to Ken Lim102090
    TI__Guru* 93670 points

    Hi Ken,

    You pulled MODE pin high and then the image is fine but the source clock jitter is over the limit or does not meet the jitter mask criteria. This means either the HDMI transmitter clock has too much jitter or your HDMI cable is too poor quality. Maybe you can first use known good short cable to first check the transmitter jitter and then once it passes the clock jitter test or mask then use a cable with MODE pin low. We need to identify if this is being caused by a jittery transmitter or if this is a cable quality issue.

    Regards,,nasser 

  • 0 in reply to Nasser Mohammadi
    Prodigy 40 points

    Hi Nasser,

    yes the HDMI transmitter clock jitter is very close to the 0.25*Tbit, it is not the cable issue. Is DS34RT5110 able to work with such clock jitter input? Is there a requirement how much jitter it can accept?

    Regards, Ken

  • 0 in reply to Ken Lim102090
    TI__Guru* 93670 points

    Hi Ken,

    Jitter tolerance on clock should not be an issue since normally Dj is zero and it is mainly Rj.

    Whether we use MODE = 0 or = 1, DS34RT5110 D_Out0 through Dout2 stay the same. We may need to concentrate on the display receiver which may not be able to track movement of Cout vs D_Out. Please run the followings two test:

    1). Using MODE =0 and C_Out to trigger the scope, capture D_Out0 through D_Out2

    2). Use MODE=1 and C_Out to trigger the scope, capture D_Out0 through D_Out2.

    The test above would show output jitter of one mode vs another.

    3). You had mentioned When using MODE =1 you can display the video but it fails C_Out Jitter test. How about if you use C_IN instead, does it fail clock output jitter test again?

    Regards,,nasser