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DP83TC811S-Q1: Automatic polarity correction cannot be disabled

Part Number: DP83TC811S-Q1
Other Parts Discussed in Thread: DP83TC811

step:

1. 0x0475 has been set to 0x2000 or 0x3000;

2. and there is no power down or reset;

3.swap the two wires of the MDI and reconnect;

4.wait a few seconds;

5.read register 1, return 0x65, it means link up;

question:

After exchanging the two wires of MDI many times, it can still link up,  isn’t the polarity adaptation disabled? When the line sequence is incorrect, shouldn’t it not be able to link up?

  • Hi Minquan,

    Can you please let me know what is the link partner used? Is the 811S programmed in Master or Slave? Is auto-polarity detection disabled on link partner too?

    --
    Regards,
    Gokul.

  • Hi Gokul,

    The link partner is Fast Ethernet Media Converter, and I try  Two types of Ethernet media converters and VGM, it still link up.

    one of the Ethernet Media Converter is the master, which does not set a auto-polarity correction switch, and dp83tc811 is used as a slave;

    one of the Ethernet Media Converter is the slave, which does not set a auto-polarity correction switch, and dp83tc811 is used as a master;

    VGM is the master, which does not set a auto-polarity correction switch, and dp83tc811 is used as a slave;

    In these three cases, after repeating the five steps described above, link up is still the same.

    Even experimented with two dp83tc811, still the same result (one as master and the other as slave).

    It's really confusing!

  • Hi Minquan,

    I suggest debugging problem with two dp83tc811 first.

    When doing the same experiment with 2 811 devices, did you program auto-polarity disable on both 811 devices?

    To disable auto polarity correction, please program 0x0475 = 0x1000. To enable auto polarity correction, please program 0x0475 = 0x0000.

    After programming register 0x0475, can you please read back the value to check if the register is programmed correctly?

    --
    Regards,
    Gokul.

  • Hi Golul,

    After many experiments (using two dp83tc811), I finally figured out that the way to verify auto-polarity correction is to judge by ping rather than by observing its link status.

    thanks.

  • Hi Xu,

    Thanks for the update.

    I hope you got everything sorted out now. If so, please mark the issue as closed.

    --
    Regards,
    Gokul.