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DP83TC812R-Q1: communication ready indicator

Chuqiang Wen
Expert 5835 points
Part Number: DP83TC812R-Q1

Hi Expert,

Do we have some register can indicate communication ready status for 811?

We found there is a register in DP83T812 which called TC1_LINK_TRAINING_TIME as below screenshot, the bit 15 indicate the TC1 comm ready signal. So does this register indicate the communication ready status for our PHY? If this bit shows communication possible, does it mean the MAC to PHY and PHY to PHY link is up? What kind of condition will cause the communication not possible? 

Do we have similar register for 811? I don't find it in datasheet.  

Thanks! 

Ethan Wen

  • 0
    TI__Expert 8721 points

    Hi Ethan,

    The suggested register to check Link Status is 0x0001 or 0x0133. This status will indicate if Link is good and the device is good for communication (PHY to PHY).

    Regards,
    Rahul

  • 0 in reply to Rahul
    TI__Expert 5835 points

    Hi Rahul,

    But 0x0001 is only for PHY to PHY link status. It cannot indicate that MAC to PHY link ready. So if only use 0x0001, I think it may not indicate the communication ready. 

    Chuqiang Wen said:
    We found there is a register in DP83T812 which called TC1_LINK_TRAINING_TIME as below screenshot, the bit 15 indicate the TC1 comm ready signal. So does this register indicate the communication ready status for our PHY? If this bit shows communication possible, does it mean the MAC to PHY and PHY to PHY link is up? What kind of condition will cause the communication not possible? 

    Besides, may you also help me understand this question? 

    Thanks!

    Ethan Wen

  • 0 in reply to Chuqiang Wen
    TI__Expert 8721 points

    Hi Ethan,

    The communication ready bit will not indicate the MAC to PHY link ready. I am not aware of any way to determine the link status between MAC to PHY in RGMII or RMII, in SGMII it can be possible after the ANEG bit is set of both the MAC end and the PHY end.

    Regards,
    Rahul

  • 0 in reply to Rahul
    TI__Expert 5835 points

    Hi Rahul,

    Thanks for your information. 

    May you also help me understand the meaning of communication ready bit? 

    Regards,

    Ethan Wen

  • 0 in reply to Chuqiang Wen
    TI__Expert 8721 points

    Hi Ethan,

    I have reached out to our design team to get more information on this, I will get back to you soon on this.

    Regards,
    Rahul

  • 0 in reply to Rahul
    TI__Expert 5835 points

    Hi Rahul,

    Please share with me once you got the feedback. 

    Meanwhile, regarding to customer's request, they would like to have a detection if the communication ready. If there don't have any way of determine the link status between MAC to PHY and PHY to PHY directly. Do you have any suggestions? 

    For PHY to PHY, we can use 0x0001 register to confirm the status. For MAC to PHY, I saw we have loopback mode, may you kindly let me know which mode of loopback we can use to detect the effective link between MAC and PHY? PCS or xMII loopback? 

    Thanks!

    Ethan Wen

  • 0 in reply to Chuqiang Wen
    TI__Expert 8721 points

    Hi Ethan,

    To validate the communication between MAC and PHY, xMII Loopback can be used. This can be used to test if all the packets being sent from the MAC are being sent properly or dropped.

    Regards,
    Rahul