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TLK10002: Is that more comprehensive description about the scramble function in TLK10002?

rocqip
Prodigy 40 points

Other Parts Discussed in Thread: TLK10002, TLK10232

Hello colleagues,

Bit 3 of the Register HS_SERDES_CONTROL_2 (R3.3) is used to control the scrambled data capability of HS port. But I cannot find any more words about the scramble function. Can you give me any hint?


We are evaluating if TLK10002 can support CPRI-9.8G protocol version 1 and protocol version 2. Is the scramble in the data sheet relative to the scramble function of these two protocol versions?


BR,

Qipeng

  • 0
    TI__Genius 16150 points
    Hi Qipeng,

    Could you take a look at TLK10232? This device is a newer version of TLK10002 and it has more features and abilities, so, I think TLK10232 is a better option.

    Regards,
    Luis Omar Morán Serna
    High Speed Interface
    SWAT Team
  • 0 in reply to Luis Omar Moran
    Prodigy 40 points
    Dear Luis,

    unfortunately I cannot change the design right now, because the hardware is already on hand. TLK10002 on the board is chosen to support CPRI-9.8G.

    There exist two protocol versions in the CPRI standard, one supports unscrambled data and another one supports scrambled data. We are not sure if TLK10002 can support both protocol versions well. By our test, it seems that TLK10002 can support the protocol version for scrambled data, but not support the protocol version for unscrambled data. Because there is no detailed information about scramble function in TLK10002's datasheet, we don't know if we config the chip correctly for both protocol versions.

    It would be grateful that you can help us to clarify the scramble function of TLK10002 and the exact meaning of Bit 3 of Register 3 (HS_SERDES_CONTROL_2). Or you might be able to directly tell us if TLK10002 can support both protocol versions of CPRI standard. :)

    BR,
    Qipeng
  • 0 in reply to rocqip
    TI__Genius 16150 points

    Hi Qipeng,

    Please let me verify if this device supports both protocols. I will be back with the answer.

    Best Regards,

    Luis Omar Morán

  • 0 in reply to Luis Omar Moran
    Prodigy 40 points
    Dear Luis,

    Do you have any further information about the Bit 3 of the register HS_SERDES_CONTROL_2? According to the datasheet, this bit will only affect the receiver of HS Serdes. What effect will it bring when we set this bit to "1"?

    BR,
    Qipeng
  • 0 in reply to rocqip
    TI__Genius 16150 points

    Hi Qipeng,

    Sorry for the delay. Basically, the TLK10002 requires that the data be 8b/10b encoded and contain control words for alignment (i.e., K28.5). So, if the data is scrambled prior to being encoded, although, the TLK10002 would not do any scrambling/descrambling itself. Scrambling is strongly recommended at higher speed (10G), since this helps avoid repetitive data patterns that would skew the behavior of the various adaptative control loops (CDR and DFE).

    In my understanding HS_SERDES_CONTROL_2 [Bit 3], selects between CDR techniques:

    Scrambled data ==> CDR can sample at tha baud rate and adjust the sampling point based on the measured precursor and postcursor effects.

    Unscrambled data (Lower Rates) ==> CDR could oversample the input data so that it can regulate the sampling point based on detection of edge tansitions.

    I hope this helps.

    Best Regards,

    Luis Omar Morán Serna

    High Speed Interface

    SWAT Team

  • 0 in reply to Luis Omar Moran
    Prodigy 40 points

    Hi Luis,

    Thanks a lot for this helpful information!

    We found out that if we forced auto-zero calibration with automatic update, then the system can somehow work with protocol 1 (unscrambled data) at 9.8 Gbps. However, it is not that stable and the receiver side will lose synchronization from time to time.

    Is there any suggestion from your side to adjust parameters of TLK10002 for improving this situation?

    Best regards,
    Qipeng

  • 0 in reply to rocqip
    TI__Intellectual 1906 points
    Hi Luis,
    Hi Qipeng,

    I am getting now more or less the same request from same customer but based in Germany. He is reporting that the link is getting unstable when using unscrambled data. Can you share some more details about the location you cover (Hangzhou??)

    To me it looks that Qipeng is still waiting for an answer on some improved settings.

    Can we move this thread also to the internal forum since we are talking customer related issues which should not get public.

    best regards, Bertram
  • 0 in reply to rocqip
    TI__Genius 16150 points

    Hi Qipeng,

    Have you tried with different settings for HS_SERDES_CONTROL_3 (HS_ENTRACK, HS_EQOPRE, etc.). As you know every system is different, hence, user needs to adjust some paramters (equalization) according to their scenario: AC losses, lenght of cables or traces, among others characteristics that impacts the transmission data. Please let me know how are you settings these parameters to provide you a better feedback.

    I hope this helps,

    Best Regards,

    Luis Omar Morán Serna

    High Speed Interface

    SWAT Team

  • 0 in reply to Bertram Brummer
    TI__Genius 16150 points
    Hi Bertram,

    If you want, we could move it, although, I do not know if Qipeng has access to internal forum.

    Regards,
    Luis