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DP83865 - MDIO, MDC Restriction

Kawai
Guru 19785 points
Other Parts Discussed in Thread: DP83865

Hello Team,

We are using DP83865 on our board and having trouble that the device would not link up when MDC is applied before PHY link up. If MDC is applied after PHY link up it it seems to be operating correctly.

Is there any restriction or special attentions using DP83865 ?

Best Regards,

Kawai

  • 0
    Guru 19785 points
    Hello Team,

    We are having trouble using DP83865, not working correctly on our board. Could you please give us your advice ?

    With default without MDIO/MDC, somehow the PHY link up on our board. Generally, I believe you would need to access and set the registers before starting link up. However in our case, when we try to start communication with MDIO/MDC before PHY link up, MDC is applied, DP83865 would not link up.

    Best Regards,
    Kawai
  • 0 in reply to Kawai
    TI__Mastermind 31600 points

    Kawai,

    The DP83865 is designed to support resistor strapping to configure default operation of the DP83865.  Therefore, register access may not be necessary to establish a link.  Having noted that, the functionality that you describe related to the MDC is not expected and should be investigated further.


    If you power up the board without an Ethernet cable connected, are you able to read the DP83865 registers?  If so, could you provide a register dump showing the register defaults?  Please read each register twice and report both values as some status bits change when read.

    As part of your initialization, are you also writing registers?  If so, could you provide details on your register writes?

    Patrick