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[ DS90UB913/4 ] ITU-R BT.656

Kenichiro
Mastermind 9165 points
Other Parts Discussed in Thread: LMH0041, LMH0040, LMH0031, CLC021

[ DS90UB913/4 ] ITU-R BT.656

Hi,

I'm often asked by customer whether DS90UB913/4 (UB913A/4A also) support ITU-R BT.656 or not, and always little bit confused.

Recommendation BT.656
http://www.itu.int/rec/R-REC-BT.656/en
 
ITU-R BT.656 from wiki
http://en.wikipedia.org/wiki/ITU-R_BT.656

As my understanding, since 913/914 are serdes devices and not depend on protocol, as far as its parallel bit match with 10bit or 12bit which 913/914 support.

However, BT.656 also defines 10bit mode, so if image sensor sends the BT.656 data with 10bit mode, it seems 913/914 can support.

May be, I totally misunderstand these standard and configuration. So it's greatly helpful, if you correct me or let me know the "good" articles.

Thanks,
Ken
  • 0
    TI__Expert 5210 points

    Hi Ken,

    From reading through this spec (http://www.itu.int/rec/R-REC-BT.656/en), it seems that the 8 or 10-bit data in the current BT 656 format is already serialized in its own specific format for transmission over a 75 Ohm coaxial cable or fibre-optic cable. Therefore, there is no need to serialize the data again through a SerDes system.

    For a parallel interface, the answer to your question is yes the 913/914 parts can support the BT 656 standard with 27 MHz clock. However, if you check the footnote on page 9 under Appendix I you will see that the parallel interface is no longer in use and only documented to support legacy installations. 

    -Sean

  • 0
    TI__Genius 13475 points

    Ken

    Although the 913/914 could transport the data, the link would not be compliant with the BT.656 spec.  For a compliant transmitter, please look at the LMH0040 or the CLC021, for a deserializer, look at the LMH0041 or LMH0031

    Mark Sauerwald

     

  • 0 in reply to Mark Sauerwald88474
    Prodigy 75 points

    Hi, Mark. Why would the link not be compliant with the BT.656 spec? Does 913/914 requires specific parallel data format? Or does 913/4 depend on the parallel data format internally? In my opinion, any synchronous parallel data can be serdesed with their clock by 913/4. Am I right? I expect your answer.

    I may be in same situation as Ken's now. First, sensor outputs 8/10-bit parallel data in BT.656 format. Second, I also need GPIO and I2C configuration function.

    BTW, since 913 has no GPI, can I use its H/VSync pins as GPI. Does this work? If not very necessarily, please do not recommend other model. You know, buying samples in China takes very loo...oong time and is expensive. However, 913/4 is handy in market instead.

    Thanks.
    Sphinxing

  • 0 in reply to sphinxing
    TI__Genius 13475 points
    BT656 specifies a specific polynomial scrambling that is to take place between the parallel and serial formats of the data. The DS90UB913A/914A use a different scrambling scheme. In addition, BT656 is very specific about the signal levels and the fact that the serial stream drives a 75Ohm cable, which the DS90UB913A does not do. For broadcast video applications, please look to the CLC021 as the serializer of choice.
  • 0 in reply to Mark Sauerwald88474
    Prodigy 75 points

    Hi, Mark. Thank you for your quick response. I appreciate it.

    I think I know exactly what you mean. You are talking about Bit-Serial Interface of BT.656. Maybe I forgot to mention this. In fact I'm using Bit-Parallel Interface(9pins of 8 data and 1 clock from sensor). Obviously, for interfacing other IC, image sensor like what I'm using usually outputs 8-bit data and pixel clock of LVCMOS level. It's just a sensor chip, not some broadcast video equipment interfacing some other one at all. Strict interface consistent with BT.656 is not required. Its output is just used by ECU or LCD in the same local system. Since that, I think this sensor's output(8-bit and clock) should be treated as normal parallel data for 913. And from this point, I'd go so far as to think that TI Channel-Link IC can be also used herein except for GPIO function. Do you agree?

    Excuse me, I still have some more questions on 913. They're all important for me. Please check my new thread and help me:
    http://e2e.ti.com/support/interface/high_speed_interface/f/138/t/390980

    Thank you very much.
    And, Merry Xmas.

    By Sphinxing