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DP83TC812S-Q1: Request for information on Auto-Negotiation

Jaidev Kaniyil
Prodigy 70 points
Part Number: DP83TC812S-Q1
Other Parts Discussed in Thread: DP83TC812R-Q1

Tool/software:

   I would like to receive information on Auto-Negotiation of  100BASE-T1 PHYs  DP83TC812S-Q1 and DP83TC812R-Q1.  In Table 7-30 of the datasheet (Page 69, Section 7.6.2.1),  it is stated that auto-negotiation is not supported by the these PHYs, and that Bit #12 of BMCR-register will be 0.  It is understandable that 100BASE-T1 links support data-rate of only 100 Mbps.   But, later in the datasheet, various bit-configurations for auto-negotiation are described.  For example, we can check as to whether auto-negotiation is complete by examining Bit #5 of BMSR Register (Page 70, Section 7.6.22, Table 7-31).  Bit #3 of the same Register indicates whether the PHY is capable of auto-negotiation.    In the Register SGMII_CTRL_, Bit #0 can be configured by us to enable or disable SGMII-auto-negotiation. Would you please let us know as to what should be the values of bits of various Registers for our network-configuration?  We do not want to use auto-negotiations.  Accordingly,  can we ignore all bit-configurations of various registers  related to auto-negotiations over 100BASE-T1 Link?  Would you please let us know as to how we should configure Bit-settings of various registers with reference to auto-negotiation?

 

Regards.

Jaidev

  • 0
    TI__Mastermind 36793 points

    Hi Jaidev,

    In BMSR register, auto-negotiation bits will refer to MDI auto-negotiation.  The DP83TC812 does not support MDI auto-negotiation.

    However, the SGMII auto-negotiation is separate from the MDI auto-negotiation.  SGMII auto negotiation is supported.  You can enable or disable this bit depending on whether you want SGMII auto-negotiation.  If you are not using SGMII, this register is not relevant.

    Thanks,

    Drew