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DS90UB962-Q1: AEQ setting

Dennis Tseng
Prodigy 120 points
Part Number: DS90UB962-Q1

Hi team,

We have a combination with DS90UB953 and 1 meter cable(RG174), and we run the maptool (ub962_margin_analysis.py).

The result is meet the recommands margin of 3 EQ levels with 4 passing strobe positions, but streaming still have some error frame occur. 

Then we change 15 meter cable and the streaming looks better. So we find out that AEQ floor default setting(0x02) maybe not lower enough for 1 meter cable. 

I'm confused about AEQ_STATUS Register (Address 0xD3) & AEQ_CTL2 Register (Address 0xD2) description when I try to configure these registers. 

  1. There is a part "The setting for the AEQ after adaption can be read back from the AEQ_STATUS register 0xD3". Is that meaning the adaptive EQ status is a current value by AEQ algorithm? Is it a dynamic value?
  2. What the different between EQ_STATUS_1 & EQ_STATUS_2?
  3. Does setting lower AEQ floor will causing any side effect when using 15 meter cable?
  4. When should the ADAPTIVE_EQ _RELOCK_TIME be set? How does it improve or what should I be concerned about?

Best regards

Dennis Tseng.

  • +1
    TI__Guru* 88020 points

    Hello Dennis,

    Dennis Tseng said:
    There is a part "The setting for the AEQ after adaption can be read back from the AEQ_STATUS register 0xD3". Is that meaning the adaptive EQ status is a current value by AEQ algorithm? Is it a dynamic value?

    The AEQ is a dynamic value which changes at starting the system and settles at the first optimal value. It keeps monitoring the quality of the link, if there are number of specific errors which is above the threshold, then the AEQ increments one value and settles again...and so on.

    Dennis Tseng said:
    What the different between EQ_STATUS_1 & EQ_STATUS_2?

    Which register is that?

    Dennis Tseng said:
    Does setting lower AEQ floor will causing any side effect when using 15 meter cable?

    No, it will have no side effect except slight extra delay (few milliseconds)

    Dennis Tseng said:
    When should the ADAPTIVE_EQ _RELOCK_TIME be set? How does it improve or what should I be concerned about?

    by changing the AEQ relock time you are changing the time the device waits for LOCK before incrementing to the next EQ value.

    If you chose small value, your AEQ will not wait long enough before settling down the correct value, which could cause multiple unlock and relock before stable.

    Choosing a larger waiting value gives the LOCK more stability but creates more delay at the system start up.

    Bottom line, the default value (2.62ms) is a good middle value and a compromise.

  • 0 in reply to Hamzeh Jaradat
    Prodigy 120 points
    What the different between EQ_STATUS_1 & EQ_STATUS_2?

    Which register is that?

    The EQ_STATUS_1 & EQ_STATUS_2  field in the AEQ_STATUS Register (Address 0xD3).

  • 0 in reply to Dennis Tseng
    TI__Guru* 88020 points

    The AEQ mechanism has two stages to increment, each stage has 8 values (000 to 111). and the status of those two stages can be seen in this register.

    The AEQ will start from 000 000, then 000 001, 000 010, ... and ends with the value 111 111

    Hope this helps!

  • 0 in reply to Hamzeh Jaradat
    Prodigy 120 points

    Thanks your explain, so can I say that channel insertion loss a lot when EQ_STATUS_2 has value?

     

  • 0 in reply to Dennis Tseng
    TI__Guru* 88020 points

    Yes, if the number is higher that means Insertion loss on the Cable/Link is higher.