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DP83867IS: When i restart auto-negotiation, Link is down

Ayse Kara
Prodigy 50 points
Part Number: DP83867IS

Hi Ti,

DP83867IS phy and PC connected using RJ-45 Connector. Before restarting auto-negotiation or software restart, link is up and auto-negotiation is completed between Pc and Phy. After  restarting auto-negotiation or software restart, auto-negotiation has still completed but link is down. Why link is down after restart ?

Do you have any recommend about this problem?

Best Regards,

Ayse

  • 0
    TI__Mastermind 19780 points
    Hi Ayse,

    Can you share the schematics of the board you are using? Can you also explain what you mean by "link is down" but auto-negotiation has completed? If auto-negotiation is complete, then I expect you have a link between the PC and the DP83867IS. Is your SGMII link down? Are you trying to ping a device?

    Best Regards,
  • 0 in reply to Rob Rodrigues
    Prodigy 50 points
    Hi Rob,

    I attached schematic under post. I did not attached schematic this message. I read 0x0001 address and i checked link status( [2] bit of register 0x0001). Before restarting auto-negotiation or software restart, link status is 1 and auto-negotiation is completed( [5] bit of register 0x0001) between Pc and Phy. After restarting auto-negotiation or software restart, auto-negotiation has still completed but link status is 0. I did not ping device because i do not know ip address of switch that is connected with DP83867IS. How can i ping device? Should i set switch port to an ip?

    Best regards,

    Ayse
  • 0 in reply to Ayse Kara
    TI__Mastermind 18425 points
    Hello Ayse,

    Did you read register 0x01 twice? This is a Latch Low bit so it needs to be read twice to get the correct indication. Are you also monitoring the Link LED to check for link up?

    -Regards,
    Aniruddha
  • 0 in reply to Aniruddha Khadye
    Prodigy 50 points
    Hi Aniruddha,

    Thank you for your reply. I read the register 0x01 twice and i saw link status is up.

    -Are you also monitoring the Link LED to check for link up?
    Yes, i am monitoring link led to check for link up.

    I would like to ask a question to you about reverse loopback. I want to check that phy to pc connection is working correctly So i tried reverse loopback. I followed these step which is given below.

    1- Loopback Configuration Register (LOOPCR), address 0x00FE, is set to 0xE720
    2-For a software reset, bit 14 of the Control Register (CTRL) ,address 0x001F, is set to '1'.
    3-Then register 0x0016 is set to 0x0020 to enable reverse loopback.
    4-register 0x001F is set to 0x4000 to apply a software restart.

    Then i send broadcast packet pc to phy and i monitored incoming packets using wireshark but i did not see any incoming packets.

    Do you have any advice for reverse loopback configuration?

    when i saw link status( [2] bit of register 0x0001) is up, is communication of phy to pc okey? Is reverse loopback needed?

    Thank you for kind interest.

    Ayse