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DP83867IR: Link Status in BMSR and PHYSTS

Hiroshi Katsunaga
Mastermind 6480 points
Part Number: DP83867IR

Hello,

My customer have some questions about Link Status bits in BMSR and PHYSTS in DP83867IR.

[Background]

They use DP83867IR in their system.

Their link was established with 1000BASE-T.

In this case, it will be in the following state.

  * LED port (1000BT link established) = 1

  * AUTO-NEGOTIATION COMPLETE in BMSR = 1

  * LINK STATUS in BMSR = 0

  * LINK_STATUS in PHYSIS = 0 -> 1 (It takes many time to change,)

They confirmed that when link was established with 100BASE-TX, LINK STATUS in BMSR became 1.

[Q1]

Is this behavior appropriate ?

[Q2]

Why does LINK STATUS in BMSR not become 1 in the case of 1000BASE-T ?

[Q3]

Why does it take many time for LINK_STATUS in PHYSIS to become 1 in the case of 1000BASE-T ?

Can LINK_STATUS in PHYSIS change at the same time as link established ?

Best Regards,

Hiroshi Katsunaga

  • 0
    TI__Mastermind 18425 points
    Hello Hiroshi,

    BMSR register bit 1 is latch low register and needs to be read multiple times when the link changes from Link Down to Link Up. This is because of how the bit is defined. PHYSTS register has a Link Status bit which serves the same purpose. This bit is not latch low and does not need to be read multiple times.

    -Regards,
    Aniruddha
  • 0 in reply to Aniruddha Khadye
    Mastermind 6480 points
    Hi Aniruddha,

    I already understand your all comments.
    They confirmed that when link was established with 100BASE-TX, LINK STATUS in BMSR became 1.
    However LINK STATUS in BMSR didn't change to 1 with 1000BASE-T when they confirmed it with same way as 100BASE-TX.

    Again,
    [Q1]
    Is this behavior appropriate ?

    [Q2]
    Why does LINK STATUS in BMSR not become 1 in the case of 1000BASE-T ?

    [Q3]
    Why does it take many time for LINK_STATUS in PHYSIS to become 1 in the case of 1000BASE-T ?
    Can LINK_STATUS in PHYSIS change at the same time as link established ?

    Best Regards,
    Hiroshi Katsunaga
  • 0 in reply to Hiroshi Katsunaga
    TI__Mastermind 18425 points
    Hello Katsunaga-san,

    Link Status in BMSR register should change along with Link LED. If the Link LED is ON then after reading BMSR register 2-3 times the LINK STATUS bit should be 1. Can you share the customer schematics along with LED connections?

    -Regards,
    Aniruddha
  • 0 in reply to Aniruddha Khadye
    Mastermind 6480 points
    Hi Aniruddha,

    Thank you for your comments.
    I received their schematics.
    I will send them to you by e-mail.

    Please check it and give me your comments.

    I will close this post because I change to communication with e-mail.

    Best Regards,
    Hiroshi Katsunaga