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Original question:

DP83822IF: PHY Link not established

DP83869HM: The PHY Link is established 1.92 seconds after the PHY becomes active.

Manisha Narayana Gowda
Intellectual 310 points
Part Number: DP83869HM

Tool/software:

Hello everyone,

I am working with the DP83869HM PHY device. In my use case, I first initialize MDIO and then the PHY.
Just before initializing the PHY, I check if the PHY is alive and linked, but it is always not linked.
I have measured the time and found it to be around 1.92 seconds. Is this the time required to establish the link?

Kind regards
Thank You
Manisha N G

  • 0
    TI__Mastermind 39855 points

    Hello,

    What speed are you trying to use in your end equipment, and what is your desired time to link? Please note that if this is 1G speed, auto-negotiation is a must and therefore will suck up time after PHY is active.

    Sincerely,

    Gerome

  • 0 in reply to Gerome Cacho
    Intellectual 310 points

    Hello,
    Thanks for your answer. In our case auto negotiation is disabled and need PHY to be linked asap.
    What is the factor which affects the time to establish the PHY link?

    Kind Regards
    Thank You
    Manisha

  • 0 in reply to Manisha Narayana Gowda
    TI__Mastermind 39855 points

    Hello,

    Auto-negotiation is the big factor in linkup time as the PHY and link partner must exchange capabilities with each other, converge to a common setting, as well as do link training. The time you are reporting is in-line with anecdotal observations seen in lab. You may either keep the auto-negotiation disabled and only go for 10/100Mbps, or enable auto-negotiation and have the 2s lead time as auto-negotiation is a requirement for 1G communication.

    Sincerely,

    Gerome

  • 0 in reply to Gerome Cacho
    Intellectual 485 points

    Hi Cacho,

    I am colleague of Manisha and have few questions on the same topic which are as follows:

    We have our PHY configuration for SPEED: 100 Mbps, Duplexity: FULL, AutoNegotiation: No. With this configuration, I am having the Link Up time of approximately 2 seconds between PHY and the link partner.

    1. Is it normal time for link up with the stated PHY configuration?
    2. Is it possible to reduce this link up time?

    Looking forward to hearing back from you.

    Best Regards,
    Hasan Aarzoo

  • 0 in reply to Hasan Aarzoo
    TI__Mastermind 39855 points

    Hi Hasan,

    If PHY is already in forced configuration for MDI, then this is generally a big configuration for shortest linkup. The only other setting to modify would be manual configuration of MDI/MDIX. 

    Is the link partner also in forced configuration, or is it also auto-negotiating/auto-MDIXing?

    Sincerely,

    Gerome