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lcd flicker problem

vakkascelik
Prodigy 120 points

Hi, all.

I have dm6446 dvevm board.

initially there was not lcd flicker problem when we first try demo programs. later I have installed and upgraded DVSDK 2.0 and MVL 5.0 tools. and then recompiled demo codecs and linux kernel. then when ı wanted to try recompiled demo programs, ı have realized that there is flicker program on the lcd. even in interface mode.

I couldn't find the solution yet. Then, I tried to press on reset button. Oopps. IT receives bootme bootme bootme.. messages. I dont know what should I do.

Waiting for your help.

Thanks a lot.

  • 0
    Prodigy 120 points

    I have understood the bootme problem and its solution by reading "http://focus.ti.com/lit/an/spraai4a/spraai4a.pdf".

    However, flicker problem still exists.

  • 0 in reply to vakkascelik
    TI__Mastermind 37340 points

    You suggested you are uisng DM6446 EVM (from Spectrum Digital) along with DVSDK 2.0 (assuming DVSDK 2.00.01.22), correct?  Also, which demo are you running and what options are you passing to the demo.  Are you seeing this flicker on the composite analog output?

    Flicker usually happens when video timing configuration is off or in a few cases when the bandwidth of a particular window is exceeded (In dm6446, there is a constrain for using VID0 for HD video because VID1 cannot keep up with HD resolutions).  But since EVM only has composite connector (used for NTSC output), you are likely not running into any of these unless you are using a daughter card on top of DM6446 EVM to exercise other resolutions.  Therefore, if I understand your setup correctly (hence why I ask for more info) we may be seeing a hardware issue here, which we can certainly help you trouble shoot. 

  • 0 in reply to Juan Gonzales
    Prodigy 120 points

    Hi Juan,

    Firstly, I should say when I open the video with media player, no flicker occurs. it plays well. The problem is due to lcd i think. Yes, we are using DM6446 along with DVSDK 2.0. it writes "Color TFT LCD Monitor" on the lcd. I think it is hardware issue. it was used to work fine at initial setup. I have brought setup to initial settings but it still does not work.

    Thank you very much.

  • 0 in reply to vakkascelik
    TI__Mastermind 37340 points

    Vakkas Celik said:

    Hi Juan,

    Firstly, I should say when I open the video with media player, no flicker occurs.

    Are you doing this on a PC or the EVM?  you would have to be doing this on the EVM to ensure same hardware + drivers are being used.  There may be nothing wrong with the stream itself, but the timing configuration programmed by the driver may not match what the display expects. 

    Are you using the same LCD when using the media player approach?

  • 0 in reply to Juan Gonzales
    Prodigy 120 points

    Hi Juan,

    Yes, I was doing it on PC.

    How can I understand whether timing configuration programmed by the driver match what the display aspects or not.

  • 0 in reply to vakkascelik
    TI__Mastermind 37340 points

    re-reading your postings, my understanding is that you are using DM6446 EVM with DVSDK 2.0 and the display that came with the EVM kit (labeled "color TFT LCD Monitor"), correct?  If so, this is a standard NTSC or PAL (should be labeled next to the serial number on the back of the display).  Since you suggest you did see a good picture before, I assume the choice between NTSC and PAL is not an issue here; I can confirm this display is compatible with our demos and you should not see any flickering on the LCD; however, you can always verufy by connecting to a different analog display (or analog TV).  

  • 0 in reply to Juan Gonzales
    Prodigy 80 points

    Could this be related to the DM644x errata regarding VID0, VID1, OSD0?

     

    We found that some DM6441 chips were rev 1.3 and some were rev 2.1pg and behaved with the output to lcd/tv looking choppy and out of focus.

    It was related to the field inversion of the composite output of the video layer combined with certain picky NTSC decoders inside various LCDs.

     

    We solved the problem by adding code to detect the chip revision and apply the appropriate workarounds specified in the silicon errata.

    Here are the registers we modified according to chip revision:

     

    rev 1.3 (DM6443):

    0x01C72600 = 0x200

    0x01C7240C = 0x00

     

    rev 2.1pg (DM6443a):

    0x01C72600 = 0x00

    0x01C7240C = 0x00

     

    Hope that helps,

    David