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Changing DP83630 (PHY) to 100BaseFX

Peter M
Intellectual 680 points

Other Parts Discussed in Thread: DP83630

I am using a Sitara (AM335x) processor which is connected to DP83630 PHY. And I am planning on connecting the PHY to SFP's. For example a SIGNAMAX 065-73TXMG SFP.

But it requires the DP83630 to be configured for100BaseFX.

We are currently doing this via a hardware strap on the DP83630 and our SFP venders are indicating that the hardware is setup correctly between the PHY and the SFP.

Unfortunately, this is not yet working.

So, a couple of firmware related questions:

1) Using ethtool, the status is indicating that the PHY is set to 10BaseT. So, is it possible that the firmware is overriding the hardware strap setting? I am using the 7.0 SDK with a DTS nearly identical to the am335x.

2) How does one force the DP83630 into 100BaseFX. The ethtool doesn't seem to have the capability.

 

 

 

 

 

  • 0
    TI__Guru**** 393215 points

    Hi Peter,

    PHY configuration is done over the MDIO interface. What is your PHY physical connection to the AM335X?

  • 0 in reply to Biser Gatchev-XID
    Intellectual 680 points

    Hi Biser,

    We have a MDIO interface to the PHY and we are using MII TX & RX.

    So, back to my question, does the firmware (from at least the AM335x EVM) use the MDIO to set a configuration to the PHY? I believe this is the same PHY that is used on the AM335x EVM.

    If so, can I change it and configure a different mode 100BaseFX on the PHY?

    Thanks

     

  • 0 in reply to Peter M
    TI__Guru**** 393215 points

    Yes, PHY configuration is done over the MDIO interface. However this PHY isn't used in any of the AM335X EVM boards. The one used on GP EVM and Starter Kit is AR8031_AL1A, which is a Gigabit PHY.

  • 0 in reply to Biser Gatchev-XID
    Intellectual 680 points

    Thank you for the clarification Biser. I happend to check the EVM schematic last night as well and realized that the AR8031_AL1A was being used.

    So, perhaps I have some more basic questions then.

    1) Even though I am using another phy, do I have to make any changes accordingly? In other words, does the code in the AM335x PSP have to be specific for my PHY (which is a DP83630)?

    2) If not, can you point me to how I can change the configuration of the PHY (via MDIO). What I am trying to do is set the PHY to 100BaseFX mode.

  • 0 in reply to Peter M
    TI__Guru**** 393215 points

    I'm not a SW expert. I will ask somebody to help on this.

  • 0 in reply to Biser Gatchev-XID
    TI__Expert 3520 points

    Hi Biser,

    The connection issue has been solved with a few takeaways involving both a hardware change and software modifications.

    1. Initially the SFP manufacturer had indicated to use the DP83630's twisted pair interface as outlined in section 9.1 of the datasheet. After observing the RX+/- signals, they were biased too high and hardware modifications were made to instead match the fiber pair interface outlined in section 9.2 of the datasheet.
    2. Auto negotiation of the PHY was turned off using ethtool which allowed the PHY to be reconfigured in 100BaseFX mode due to the straps. The following commands disabled autonegotiation and enabled full duplex. Please note, eth0 was the network device name for our connection, others should replace with their own device name.
      1. ethtool -s eth0 autoneg off
      2. ethtool -s eth0 duplex full

    Following the above two changes, the system was able to successfully request an IP address using udhcpc and establish a connection to a network.

    Best Regards,

    Mark-

  • 0 in reply to Mark Swanson
    TI__Guru**** 393215 points

    Hi Mark,

    Thanks for sharing the solution on the forum! This can be helpful to other people who face a similar issue.

  • 0 in reply to Biser Gatchev-XID
    Intellectual 680 points

    Thanks Mark.

    We are modifying our hardware as per your work with the other team. Unfortunately, we are still having some issues.

    Anyway, I will dig in a bit more and update the form when I find the root cause.

     

     

  • 0 in reply to Peter M
    Intellectual 680 points
    Sorry for the late response. As a follow up, we re-checked our hardware modification and they were the same as Mark had mentioned above.

    So, to get it to work, we disconnected the ethernet cable and re-attached, and the connection worked.

    Still looking into why this is occurring.

    Peter M.