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TLK10034: TLK10034EVM

alain dugas
Prodigy 20 points
Part Number: TLK10034
Other Parts Discussed in Thread: TLK10232

Hello,

I am using the TLK eval board.

There is 4 10G channel available with my board (Lane A, B, C and D).

My objective is to use 10GBaseKR, with autoneg and training.

When i loopback lane C to lane D (for example), so:

         Lane C Tx+/- <> Lane D Rx+/-

         Lane C Rx+/- <> Lane D Tx+/-

It works fine, the link is UP, and  autoneg says 10GBaseKR. Training is fine also.

But when i loopback lane C (for example) on itself, so:

       Lane C Tx+/- <> Lane C Rx+/-

it doesn't work, link remains DOWN.

Is it normal, or does it need somme specifics initialisation to run?

I am wondering about that because i want to use this kind of loopback to test my future design. 

Regards.

Alain.

  • 0
    TI__Mastermind 19155 points

    Hi,

    You should be able to loop back a 10G channel to itself, such as lane C. I don't have a TLK10034 in my lab but I have TLK10232 one which is basically the 2-channel version of the same PHY.  See my example instructions and result for looping back lane B on the TLK10232 EVM using the TI GUI.

    • Make sure to enable “apply channel A settings to channel B”

     

    • Make sure to enable PRBS functions and load script and apply script with 10G KR option ("via load script)

    • Make sure you connect Tx output p to Rx input p signal and Tx n to Rx n
    • Make sure to use SMA cables of same part number and length to connect  channel B Tx outputs to Channel B inputs
    • You may need to clear the counters after initial setup. You can do that by clicking on “reset cumulative”

    Thanks,

    Rodrigo Natal

  • 0 in reply to Rodrigo Natal
    Prodigy 20 points

    Hello, 

    I follow your advices and get good results for BER test, but the link stays DOWN.

    I am wondering why it is not possible to get a link UP when Tx is loopback to Rx of the same channel,

    with autoneg and training OK? 

  • 0 in reply to alain dugas
    TI__Mastermind 19155 points

    I'm not sure why link is not coming up. Couple debug questions below.

    1. Have you reviewed the TLK Status registers? Such as,
      1. HS Serdes status
      2. KR_TRAIN_STATUS
      3. KR_LINK_PARTNER_STATUS
    2. If you disable LT/AN, does the link come up?

    Thanks,

    Rodrigo Natal

  • 0 in reply to Rodrigo Natal
    Prodigy 20 points

    HS_Serdes Status: Which one? I note that HS_PLL is locked.

    KR_TRAIN_STATUS: 

      KR_Link_Training status: all is white, nothing in green (No training failure detected, no startup protocol in progress.)

      KR_Link Partner Status: Training should continue and not update for all coeff

      KR Local device status: Training should continue and not update for all coeff

    I see also errors on TX and Rx Path with PCS and PMA Status (PCS and PMA receive link are not UP)

    If i disable LT/AN (i force 10GKR instead of autoneg), then Receive link is OK for PCS and PMA. In this case i see also errors but only on Tx path.

    Regards.

    Alain.

  • 0 in reply to alain dugas
    TI__Mastermind 19155 points

    Thanks for the update. For the case where you loopback lane C to lane D, what results do you observe for these same status indicators?

    -Rodrigo

  • 0 in reply to Rodrigo Natal
    Prodigy 20 points

    When i loopback C to D, then autonegociation status says: Autonegociation is OK,and link is UP, for both lane (C and D).

    The KR standard status says: "training is complete",  "receiver is trained and ready to receive data" for both lane too.

    Speed is negociated at 10G, with FEC.

    I also see error on TxPath, on  both lane.

    If i choose to be only 1G able,  autonegociation succeed, and there is no errors on TxPath.

  • 0 in reply to alain dugas
    TI__Mastermind 19155 points

    Perhaps there is an issue with self loopback case specific to 10G-KR. I would recommend then to use the "C to D" configuration for KR link evaluation with TLK evaluation board. If the link partner Rx is not observing errors then this TxPath error should not be an issue.

    Thanks,

    Rodrigo