Search FAQs on the left to see if your question has been answered. Click on the dropdown to view all of the documents associated with the product. If you can't find your question, click on Ask a Question

Black line on the Output from the ADV7282-M

u!

This FAQ was generated from the following discussion: Black line on the Output from the ADV7282-M

Comments
Anonymous
Parents
  • Dear expert

             I can't upload attachment to here, you can get attached file from the follwing link:

    https://sendspace.com/file/ymitic

  • Hi Yuanyuan guo,

    It looks like you are programming the ADV7282-M correctly.


    One thing you state that with a PAL input, the output is 480 lines long. Is the output 480 lines long for NTSC inputs too?

    The ADV7282-M outputs 487 lines of video in BT656-4 progressive NTSC mode. Could this be the cause of your issue?


    Could you also try reading the registers 0x10 to 0x13 in the fail state.


    Could you also try recreating the issue on an ADV7282-M evaluation board. If you do not have one you can contact your local Analog Device's sales office to have one shipped to you. I can forward you an email address if you do not have one.


    thanks and regards,

    Robert


  • Dear expert

         I think this may be parameters settings issue, I did a set of experiments as follows:

         In order for the receiver to correctly receive video data, It is necessary to tell  the szie of  video data,also included video data + blanking data in platform side(receiver).

        

    ADV7282-M output format      video data        video data + blanking data       test results

               BT656-4                          1440x487                     1728x525                       Images is displayed correctly(no 10lines dark and  a black line) ,but  a error is receiver has received the 507 lines.

               BT656-4                          1440x507                     1728x525                       there is a black line at botton of image,no any software error

               BT656-3                          1440x487                     1728x525                      more than 10 dark lines at top of image,and  a error is receiver has received the 507 lines

               BT656-3                         1440x507                     1728x525                       10 dark lines at botton of image,no any software error

               Image is displayed correctly in the first set of experiments,and only has a software error.

               The ADV7282-M outputs 487 lines of video in BT656-4 progressive NTSC mode,Why receiver does receive is 507 lines? I initialize ADV7282-M wiht parameters of "I2P AUTODETECT CVBS Single Ended In Ain 1, 480p/576p MIPI Out", Is it related to this settings?          

  • Hello Yuanyuan Guo,

    Thanks for reading those registers. Register 0x12 states that sometimes the ADV7282-M receives CVBS video of non-standard horizontal line length. This may be related to your issue.

    You may be correct in this issue being due to a screen resolution issue. I will run some experiments in the lab to see if I can recreate your issue.

    Note that when a CVBS source is disconnected from the ADV7282-M it will output a few frames of video of non-standard length (i.e. greater than 576 lines lines of video) until it enters free-run mode. These non-standard line lengths can sometimes cause input buffers on the MIPI receiving device to overflow.

    I would advise implementing a line counter or similar control loop, to prevent issues in your back end processor.

    regards,

    Robert

  • Dear expert

          Could you recreate this issue in the lab?

           I think it is difficult  to implement a detection mechanism in back end processor.

           I'am checking it,thanks!

  • Dear expert

    Local Analog engineer Bob Gao sent me some pictures.
    It showed that image had 507 lines whether ADV7282-M output BT656-3 or BT656-4 format based 480P.

    Everything is normal in free-run mode,but there is a black line at botton of image when using a extern analog camera,DVD device or TV Pattern generator.
    I want to make sure that if this issue has occurred after I2P process.
    Register 0x12 states that sometimes the ADV7282-M receives CVBS video of non-standard horizontal line length,so an error occurred during the I2P process.

    How can  I confirm?

  • Dear expert

            Our back end process can't do I2P process,I disabled ADV7282-M I2P function,

    A balck line shown in a field.

             You can get video(3.0MB) from following address link:

             https://www.sendspace.com/file/xlrigl

Comment Children
No Data
Related