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DS90UB954-Q1: AEQ setting to ensure communication stability

Tomoaki Yoshida91
Genius 5255 points
Part Number: DS90UB954-Q1

Hi team,

Our customer is considering AEQ setting to ensure communication stability.

I understand that there is a trade off with lock time, but they allow longer lock time.

We would like to optimize AEQ so that the lock is less to lost.

Please advise how to set the following registers on the premise.

・0x42 AEQ_CTL1

To make it more severe, 2step is enabled.

AEQ_ERR enables all three items.

Is this correct?

How should we set AEQ_OUTER_LOOP and AEQ_SFILTER_EN?

・0x43 AEQ_ERR_THOLD

Set to 1.

・0xD2 AEQ_CTL2

ADAPTIVE_EQ_RELOCK_TIME should be set as long as possible within an allowable range.

AEQ_1ST_LOCK_MODE should be 1.

・0xD4 ADAPTIVE EQ BYPASS

Since AEQ does not bypass, setting is not necessary.

・0xD5 AEQ_MIN_MAX

Set as necessary.

I am thinking about setting as below.

Addr:0x42 data:0x75

Addr:0x43 data:0x01

Addr:0xD2 data:0xF4

Addr:0xD4 data:0x60(default)

Addr:0xD5 data:0xxx

Can you give me advice on register setting regarding AEQ?

Best regards,

Tomoaki Yoshida

  • 0
    TI__Genius 10475 points
    Yoshida-san,
    I am not sure if I understand correctly the reason for trying to optimize the EQ setting. You're correct there is a trade-off between deserializer lock time and AEQ settings range (full range or partial), but if you let the AEQ adapt it should find the optimal setting based on the effects of cable loss/length and aging and temperature effects. You can refer to the 954 datasheet 7.4.9 for adaptive equalizer information and how it works.

    Is your customer seeing unstable LOCK with AEQ on? What is their cable length and loss?

    As the AEQ section in the datasheet describes, AEQ_MIN_MAX register 0xD5 only needs to be set if you are limiting the AEQ range by specifying a min and max value. All the other register settings you mention looks like are set to default except 0x42[3] AEQ_2STEP_EN which controls how long the state machine waits before checking for errors.
  • 0 in reply to Palaniappan Manickam
    Genius 5255 points

    Hi Palaniappan-san,

     

    Thank you for your support.

    Our customers are going to conduct a communication performance test combining several cable lengths in order to confirm the stability of communication.

    So they are thinking about how to set AEQ.

    They should not set minimum and maximum.

    I believe that it will be optimized the equalizer by extending the relock time and enabling error control.

    Is there anything else they need to change?

     

    Best regards,

    Tomoaki Yoshida

  • 0 in reply to Tomoaki Yoshida91
    TI__Genius 10475 points
    Yoshida-san,
    They can leave the settings to default unless they specifically see a need to change something. In that case they can refer to the register descriptions in the datasheet.

    In any case it looks like the values proposed are all same as default except for one as I pointed out.