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DP83867E: Link status check upto cable plug-in

Ella KIM
Expert 4212 points
Part Number: DP83867E

Hi ePHY folks,

My customer  designs DP83867E for debugging port. So this ethernet cable is usually unplugged. When it is plugged, they first want to check if the link is correctly established. Could you advise the simplest way to check the link status? Maybe register 0x0005?

Thank you.

  • +1
    TI__Genius 16030 points

    Register 0x0001 gives the link-status.

    --

    Regards,

    Vikram

  • 0 in reply to Vikram Sharma
    TI__Expert 4212 points

    Hi Vikram,

    There was a misunderstanding on customer's requirement from my side.

    My customer will implement a code in FPGA that resets ePHY if there's an error in link upon cable plugging. If the code is implemented with register 0x0001, FPGA will always try to reset ePHY even when the cable is not connected. Can DP83867E support this function thru any register or SMI (MDIO interface)? Please advise.

  • 0 in reply to Ella KIM
    TI__Genius 16030 points

    Hi,

    PHY can not detect if the link is down because of no cable connection or because of the link-partner. 

    If the cable is removed then link will not recover on reset :) and then their software may stop doing the reset after one reset.

    --

    Regards,

    Vikram

  • 0 in reply to Vikram Sharma
    TI__Expert 4212 points

    Hi Vikram,

    (1)

    What's the value of link-status bit in register 0x0001 when there's no cable connection (no link-partner connected)? 0 or 1?

    If the software stops doing the reset after one reset while the cable is disconnected, it would not restart reset even in the case when the link is not established when the user connects the cable again, because the bit stays 0 regardless of the cable connection status. Could you advise?

    (2) 

    Is there a register to tell if the cable is connected or not? It looks there is no such register per datasheet. Then should they implement additional circuitry to detect it?

    (3)

    Is there a register to tell if the PHY chip is initialized normally upon reset?

  • 0 in reply to Ella KIM
    TI__Genius 16030 points

    Ella,

    As I mentioned earlier, there is no bit to indicate whether the cable is connected or not. Only way to detect an open cable etc is to run the TDR. For TDR to run successfully/reliably, link has to stay down during TDR run. Refer to section 8.4.6.1 for further details of TDR.

    --

    Regards,

    Vikram