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DP83TG720S-Q1: SGMII testing

Satish Lal Das2
Expert 1900 points
Part Number: DP83TG720S-Q1

Hello,

We have a J721e based custom board with DP83TG720S-Q1 SGMII PHY. We are using the "DP83TG720 Media Converter Evaluation Module" to test the SGMII connection. Ethernet ports are connected via TE Matenet connector between our J721e & "DP83TG720 Media Converter Evaluation Module".

PHY Device driver on J721e has been written to work in 1Gbps -Full-Duplex mode (No auto-negotiation). Could you please let me know what changes I have to make in the "DP83TG720 Media Converter Evaluation Module" to ensure it doesn't request auto negotiation and always works in 1Gbps - Full-Duplex mode?

I found the User Guide here : https://www.ti.com/lit/ug/snlu289/snlu289.pdf?ts=1607973955431&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FDP83TG720S-Q1 but didn't find the answer.

Thanks,

Satish

  • 0
    TI__Genius 11725 points

    Hi Satish,

    I may have some misunderstanding here. The DP83TG720 is a single speed PHY. The only speed is 1Gbps, and will always be set for this speed. Was there a configuration issue?

    Thank you,

    Nikhil

  • 0 in reply to Nikhil Menon
    Expert 1900 points

    Hi Nikhil,

    From the DP83TG720 PHY datasheet, we found there are two registers i.e. SGMII_CTRL_1 & SGMII_CTRL_2 is used for auto-negotiation and that was confusing to us. Thank you for confirming that it is single speed PHY. 

    our Testing setup is like below 

    J7 (720 PHY configured as Master) <----TE Connector ----> "DP83TG720 Media Converter board" <-----RJ45 Connector ----> Lnux PC

    Do you recommend configuring 720 PHY on "DP83TG720 Media Converter board" as Master or Slave (Jumper J2 settings)?

    Thanks,

    Satish

  • 0 in reply to Satish Lal Das2
    TI__Genius 11725 points

    Hi Satish,

    For Automotive Ethernet PHYs, if there are two PHYs to be connected across a cable and link up, one must be configured for master and one for slave. Thus I would recommend setting the DP83TG720 for whichever mode is the opposite of it's link partner. There is no particular advantage for either, the two link partners must have one master and one slave device. I hope this helps!

    Thank you,

    Nikhil