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Original question:

[FAQ] How to Confirm Ethernet PHY Strapping

DP83869HM, What is the Ideal time to get the LINK back after resetting the PHY?

Manisha Narayana Gowda
Intellectual 290 points

Hello experts,
As soon as I reset the PHY, link is vanished for some time. It takes few seconds to establish the link again.
What is the Ideal time to wait after the reset of the PHY is done.
I am resetting the PHY by setting the 15th bit (RESET) of the BMCR register.

Thanks in advance
Manisha

  • 0
    TI__Mastermind 39845 points

    Hi Manisha,

    I assume you are linking up in 1Gbps. Taking a few seconds maximum is expected behavior as the PHY needs to auto-negotiate with its link partner. Thus, the link partner being used will play a factor into the linkup time. Is this an acceptable linkup time for you application?

    Sincerely,

    Gerome

  • 0 in reply to Gerome Cacho
    Intellectual 290 points

    Hi Gerome,
    Thanks for your reply,
    I am trying to reset the PHY after which I am switching off the auto negotiation mode. Linkup time being few seconds is fine for the application.
    I would like to know what is the maximum time period after which the link is established.
    In the application PHY do not run in the auto negotiation mode. Below are the steps defined for initializing the PHY.

    • Check if the PHY is alive 
      • Reset the PHY state machines
      • Wait until the reset is done
      • if the reset is completed
        • Disabling the auto negotiation mode is disabled
        • Set the PHY in normal mode by disabling the Isolate mode 
        • Set the PHY in normal mode by disabling the power down mode 
        • Configure the speed and duplexity of the PHY device  
        • Configure the MDI Crossover Mode by setting the 
      • wait until the link is set up
      • Link is established 
    • If the PHY is  not alive
      • Initialization is failed

    Thanks and Regards
    Manisha

  • 0 in reply to Manisha Narayana Gowda
    TI__Mastermind 39845 points

    Hi Manisha,

    For 1Gbps linkup, the PHYs need to go through the auto-negotiation process. They are not recommended to be configured in auto-negotiation disable mode if the intended speed is 1Gbps.

    There is no quantifiable data for linkup time period as this is heavily dependent on the DUT and its link partner. However, the expectation is a few seconds at most.

    Sincerely,

    Gerome

  • 0 in reply to Gerome Cacho
    Intellectual 290 points

    Hi Gerome
    Thanks for the information.
    The max speed can be configured under the non auto negotiation mode is 100 Mbps. 1 gbps is not intended to use anyhow.
    Linkup time is period info is useful for the further investigation.
    Regards
    Manisha