• State Resolved
  • Locked Locked
  • Replies 6 replies
  • Subscribers 33 subscribers
  • Views 617 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

DP83630: application note related to Link Quality Monitor Register/Link Quality Monitor Register 2

Tohru Sakuma
Prodigy 580 points
Part Number: DP83630


My customer is asking to get application note etc to describe how to use Link Quality Monitor Register/Link Quality Monitor Register 2.

Is there any material to do it ? 

  • 0
    TI__Expert 7040 points

    Hello Tohru,

    There is a detailed description of the Link Quality Monitoring feature in the DP83630 datasheet section 5.11.2 as well as register descriptions for each bit in the Link Quality Monitor registers. There is not an application note specific to the Link Quality Monitor registers. 

    Regards,

    Justin 

  • 0 in reply to Justin Lazaruk
    TI__Prodigy 580 points
    Justin Lazaruk said:

    Hello Tohru,

    There is a detailed description of the Link Quality Monitoring feature in the DP83630 datasheet section 5.11.2 as well as register descriptions for each bit in the Link Quality Monitor registers. There is not an application note specific to the Link Quality Monitor registers. 

    Regards,

    Justin 

  • 0 in reply to Tohru Sakuma
    TI__Prodigy 580 points

    Our customer explained the background about this question as follows.  

    there are 3 types of cable( same wire and sane connector) of  0.9m, 3m, 10m to connect the systems.

    They found it that  link up speed of 0.9 m cable are different from 10 m cable.

    (0.9m of cable is slower than 10 m cable.it depends on cable not system)

    They suspect the quality of 0.9m cable and tried to check whether quality is good or bad by using the DP83630 cable length measurement.

    As the result of it , DP83630 shows following response.   

    10m cable → about 0x0F (15m)
    0.9m cable → 0xFF (not measurable)

    since in the case of extremely short cables (for example 1 m or less) they don't know which number is correct ( 0x00 or 0xFF)

    If the short cable is detected by E2E response as 0m as you commented, 0.9m cable may have any problems.

    Do you think Link Quality Monitoring feature in the DP83630 is effective to check cable quality instead of cable length measurement by it ?

     if signal is enough good. 

  • 0 in reply to Tohru Sakuma
    TI__Expert 7040 points

    Hi Tohru, 

    The Link Quality Monitor would be appropriate for determining the quality of the cable rather than cable length measurement at such short lengths. 

    What is the issue you are attempting to solve with the cable length and link quality monitoring tools? 

    Regards,
    Justin 

  • 0 in reply to Justin Lazaruk
    TI__Prodigy 580 points

    The purpose is to clarify why there are differences of 0.9m and other length like 10m in link-up times.

    -DP83630 are used for both host and terminal

    -the attached eye pattern of 0.9m cable is good,

    -The attached wave form shows it seems there are many restart cycles, though  the FLP pulse is not displayed because it is too narrow in range.

    Blue :LED link 

    Yellow :TD

    Green :RD

     I have following question from my customer.

    1. what is condition to set on 0 of  SD_OPTION register  by this device though they use its default value.

      At the case of 10m cable    SD_OPTION register is 1.

     At the case of 0.9m cable    SD_OPTION register is 0

    Signal Detect Option:
    1 = Default operation. Link will be asserted following detection of valid signal level
    and Descrambler Lock. Link will be maintained as long as signal level is valid. A loss
    of Descrambler Lock will not cause Link Status to drop.
    0 = Modified signal detect algorithm. Link will be asserted following detection of valid
    signal level and Descrambler Lock. Link will be maintained as long as signal level is
    valid and Descrambler remains locked.

    2.When they don' t use Link Quality Monitor Register, Is there any condition to restart DSP ?

    "The Link Quality Monitor may also be used to automatically reset the DSP and restart adaption. Separate
    enable bits in LQMR and LQMR2 allow for automatic reset based on each of the parameter values. If
    enabled, a violation of one of the thresholds will result in a restart of the DSP adaption. In addition if the
    PCSR:SD_OPTION register bit is set to 0, the violation will also result in a drop in Link Status."

  • 0 in reply to Tohru Sakuma
    TI__Expert 7040 points

    Hi Tohru,

    1) If you are asking in what conditions would an application use SD_Option=0 rather than default setting, you may want to keep link when descrambler loses lock if it is during an idle period or you are not concerned about data errors and believe descrambler lock will recover without needing to reaquire link. That may be an option using this register bit, although not likely in most applications. 

    2) There is not a way to restart DSP without Link Quality Monitoring thresholds being violated. 

    Regards,
    Justin