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DP83869HM: RGMII to 1000BASE-X without auto negotiation

Chris van veenen
Prodigy 30 points
Part Number: DP83869HM

Tool/software:

For my internship i am working with an DP83869HM in combination with an SFP module to get an 1000BASE-SX link with an off the shell 1000BASE-SX to 1000BASE-T media converter.
If i externally loop back the SFP module the phy is able to setup an link with auto negotiation, so i know my own designed PCB works.
When i connect it with the off the shell converter i do not receive a base page, so i think the media converter does not support auto negotiation.

if i also disable the auto negotiation an the DP83869HM the phy indicates is has a link, and the kernel status its a 10Mbs half duplex link (what is strange decease my fiber communication has a sepret TX and RX). 
The media converter keeps indicating it does not have i link, and i am not able to ping anything (what i expected).

i did try to change thinks like the CTRL0_SPEED_SEL and CTRL0_DIPLEX _MODE in register C00h but all with the same results.
Just like without auto negotiation it always falls back to 10Mbs half duplex.

Does anyone have a clue how to deal with this?, or should i just find an other media converter that does support auto negotiation?

  • 0
    TI__Genius 12816 points

    Hi Chris, 

    Have you tried changing the strap setting on DP83869HM to force the PHY into 1Gbps forced mode?
    If the strapping option enables auto-negotiation, you will have to disable auto-negotiation by writing to 0 to bit 12 of register C00h and then do a soft reset of the device (write 4000h to register 1Fh). 

    If not, please check if it works with different media converter.

    Best,
    J 

  • 0 in reply to J
    Prodigy 30 points

    Hi J,

    Yeah i have tried to writing 0 to bit 12 of register C00h, and i do get a link but the kernel only indicates a 10Mbs half duplex, and i can't ping any thing on the network. It does not mater if i do a fiber loop-back (TX of my board back to RX of my board), connect both fibers from my board to the media converter or only connect TX of the media converter to RX of my board. i always get the indication i have a 10Mbs half duplex link.

  • 0 in reply to Chris van veenen
    TI__Genius 12816 points

    Hi Chris,

    What loopback have you done? Is it the loopback mode within the PHY? If so, I may check if SFP module is working properly by ABA swapping it.

    Best,

    J

  • 0 in reply to J
    Prodigy 30 points

    Hi J,

    I have done a fisical loopback by connecting TX and RX to each other. I think the SFP works properly, becease i have tested it with auto negotiation and received all the thinks i advertised with (FX_ANADV registers C04h) back on (FX_LPABL register C05h). i got the feeling i have to do more then writing 0 to bit 12 of register C00h and doing a soft reset, to force it in a 1000BASE-X full-duplex mode

    Best,

    Chris

  • 0 in reply to Chris van veenen
    TI__Genius 12816 points

    Hi Chris, 

    I understand. 
    To set the PHY to 1000BASE-X full-duplex, the setting mentioned earlier is the only setting needed to be modified. 

    If you could try with the different media converter, or try to see if you can connect to any fiber link partner, that would be very helpful to isolate the issue between the PHY's auto-negotiation setting and the media converter.

    Could you send us the register dump of C00 to C30h when this "link" occurs so I can look for anything odd in the register status?

    Please let me know. 

    Best,
    J

  • 0 in reply to J
    Prodigy 30 points

    Hi J,

    I connected a other optical media converter that we had laying around (from witch it was unclear what wavelength it uses), and i now do get a link.
    It's operating in a forced 1000base-x mode, and i am able to ping other devices in the network. 
    What the problem exactly is with the other media converter is not clear, but at least i can continue with my project.

    Thank you for your support.

    Best,
    Chris

  • 0 in reply to Chris van veenen
    TI__Genius 12816 points

    Hi Chris,

    Great to hear!

    Best,

    J