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DP83848 link status .

Aking Jin
Intellectual 465 points
Other Parts Discussed in Thread: DP83848C

I'm working on a board with LPC1788 which have an ethernet ic (DP83848C). I have looked for some examples of DP83848's configuration,I've followed the example, and questions come out.

I can talk to dp83848c, because read_phy and write_phy really work,I can get ID from DP83848 through read_phy and write_phy,  then I write BMCR with manual configuration,for instance,10M , half-duplex, then i try to get link status from BMSR or PHYSTS , It's always un linked . but the LED lamp of the PC's ethernet start to flash. and Winxp shows try to get IP.

could you there any one could help me out?

  • 0
    TI__Mastermind 31600 points

    I have a few questions that may help me get a better understanding of the behavior you are seeing:

    1. Is the board you are working with a prototype board of your own design or an existing reference design from a third party? 
    2. What does your test setup look like?  Is the link partner Phy the Ethernet port of another PC?  Do you have any access to or control over the link partner Phy?
    3. You mention that you can read the Phy ID.  Is it possible to read the contents of all the registers?

    Thanks,

    Patrick

  • 0 in reply to Patrick OFarrell
    Intellectual 465 points

    Thank you very much for your reply.

    1.we have refer to a third party design for this part.

    2. First. i have configured the LPC1788 ethernet registers. Second.  I reset the phy(DP83848C) until reset was done and then I write to the BMCR with 10Mb/s and half-duplex. The board was linked to my pc via a network cable. when I write 10Mb/s , half-duplex, the lamp of ethernet on my pc start flash, my winxp shows try to get ip.

    recently, I found that if I configure it as auto-negotiation, my pc  always shows unconnected.  and the link stastus was always not established.

    3.yeah. I have write a value to the register and read it out,  it was the same.I just test the BMCR.

    Thanks,

    Aking

  • 0 in reply to Aking Jin
    TI__Mastermind 31600 points

    Aking,

    When you force the DP83848C to 10Mb/s, half-duplex, does it successfully link to the PC?  Have you seen any cases of a successful link for any configuration settings of the DP83848C?

    Do you have any control or visibility of the PC networking configuration?  Normally, connecting via auto-negotiation is preferred since that allows the Phy devices to choose the best link. 

    Do you have the ability to probe signals on the board?  For example, could you probe the signals being transmitted to and received from the partner?

    Patrick

  • 0 in reply to Patrick OFarrell
    TI__Mastermind 31600 points

    Hi,

    I have moved your post to the Ethernet forum.  To help with better supporting and tracking your future questions in Ethernet, please post any new Ethernet related questions into this forum.

    Thanks!

    Patrick