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How to configure the CCDC to interconnect with TW2864 codec chip?

Jason wong
Prodigy 90 points

Other Parts Discussed in Thread: TVP5158

Hi, all

    I doubt the following question when i configure the CCDC(DM6441) to interact with the codec  chip, TW2864:

   1) the output of TW2864 chip is 4 channel CIF Time-multiplexed format BT.656 with 54MHZ which is not standard BT.656 but time-multiplexed, so the CCDC is configured

      as RAW mode to accept the data. in hardware,  i only connect the TW2864'S PCLK and 8 output data line into CCDC's plck and CCD[7:0] respectively, and no  VD/HD/C_FIELD. is there anything wrong?  if that's right,  what i doubt is: what's the condition of VDINT0 and VDINT1 if no external VD/HD input?

   2) In my case,  the RAW mode is the only choice ?  or is there some other choice, such as YUV interface?

BR,

-JASON

  • 0
    TI__Mastermind 37340 points

    Three modes of video input data are supported: BT.656, RAW, and YCbCr.  BT.656 standard defines embedded syncs; therefore you do not need the VD, HD, or C_FEILD signals connected, but with the other two modes (RAW or YCbCr) you do.

    I would recommend trying to configure DM6441 to use BT.656 first; if that does not work due to the non-standard nature of the input you described, then you will need VD, HD and C_FIELD signals connected as well and you can use either RAW (does not care about pixel format) or YCbCr (recommended if you know your pixel format is YCbCr 4:2:2, the standard pixel format used by television standards).

  • 0 in reply to Juan Gonzales
    Prodigy 90 points

    Hi, Juan, Thnaks for your reply.

    but in my opinion, BT.656 mode doesn't work correctly in my scene where the input data stream looks like :

    the format is 4-ch CIF Time-multiplexed BT.656. NOT the standart BT.656 stream. so we can't use the BT.656 mode. i think that the RAW mode is my only choice. is right?

    the hardware connection between TW2864 and VPFE(CCDC) is looks like:

    there is no VD/HD/C_FIELD to connect into CCDC. so if i use RAW mode, my question is : 1) how is the VD/HD pulse generated? 2) how is the VDINT0 and VDINT1 trigered?

    BR,

    -JASON

     

     

  • 0 in reply to Jason wong
    TI__Mastermind 41665 points

    Jason wong said:
    i think that the RAW mode is my only choice. is right?

    RAW mode makes the most sense for the timing diagram you show, the way the data is coming in the other standard based modes will not offer any value over a RAW capture direct to DDR.

    Jason wong said:
    1) how is the VD/HD pulse generated?

    This is a real problem, if your source cannot accept or generate syncs than the video port will not be able to capture the stream properly, in this particular case since the individual channels appear to be asynchronous to each other there is no place for a traditional sync to be anyway. The hardware is not designed to capture this sort of stream, so you would end up generating HD and VD signals with some external hardware and than sorting out the data in software, I am not sure if there will be additional timing complications capturing data continuously with the VPFE (it is designed to capture frame sized blocks of data, not a true contiguous stream of data). At a minimum you would have to define an arbitrarily large frame buffer to fill with the VPFE that you would then sort out later in software, it may make more sense to have this sorting operation done in a FPGA which would buffer up the data and synchronize it line by line or frame by frame so that it goes into the VPFE more cleanly, this would also solve the sync problem since the FPGA could generate syncs. 

    Jason wong said:
    2) how is the VDINT0 and VDINT1 trigered?

    This really depends on how you solve the prior problem of getting VD and HD pulses, as the VDINT signals are dependent on the syncs happening.

  • 0 in reply to Bernie Thompson TI
    Expert 1225 points

    I also want to use this sort of another ADC.Can you help me ??

  • 0 in reply to Jason wong
    Prodigy 10 points

    The TVP5158 of TI has the same feature of Time-multiplexed BT.656. My schedule is held by the Time-multiplexed BT.656. Is there only one choice of RAW mode to solve the Time-multiplexed BT.656? No other methods?