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DP83869HM: MDI-connection with SGMII usage

Alex Paul
Expert 5495 points
Part Number: DP83869HM


If I use two PHYs in this way: 

MCU <===RGMII===> 1st PHY (RGMII to SGMII bridge mode) <===SGMII===>2nd PHY(SGMII-to-Copper) ===> RJ45 with integrated magnetics

Do I need still need to connect the MDI-Interface of the 2nd PHY ?  

I noticed, that i received Link detect information on SGMII. 

Does anybody know what informations are transmitted via SGMII and which information require an MDI interface when the configuration is hard wired.

  • +1
    TI__Expert 8731 points

    Hi Alexander,

    Alex Paul said:
    MCU <===RGMII===> 1st PHY (RGMII to SGMII bridge mode) <===SGMII===>2nd PHY(SGMII-to-Copper) ===> RJ45 with integrated magnetics

    In this above setup 1st PHY is being configured as a media converter so no MDI interface is required for 1st PHY.

    MDI-interface is required for 2nd PHY to achieve the copper interface. MDI stands for Media Dependent Interface, it can either be copper of fiber depends on the PHY.

    Alex Paul said:
    Does anybody know what informations are transmitted via SGMII and which information require an MDI interface when the configuration is hard wired.

    Media Independent interface (SGMII) carries digital information from the MAC and the MDI interface carries analog information to the media/ line side.

    For RGMII and other parallel interface Link detect is only possible on the MDI side, where as for SGMII Link detect feature is available which helps when using fiber on the media interface.

    Hope this helps.

    Thanks,
    Rahul

  • 0 in reply to Rahul
    TI__Expert 5495 points

    Hi Rahul, 
    srry I messed up with the wording.  I meant the management Interface. Is the Management Interface required for both Phys  when I do the configuration on by hardware wirering? 

    Regards

    Alex

  • +1 in reply to Alex Paul
    TI__Expert 8731 points

    Hi Alex,

    If the PHY is configured by strap configuration MDC/ MDIO is not required for the functionality of the PHY, but if you want to debug read/ write registers it will become challenging without management interface.

    Regards,
    Rahul