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DP83869HM: media converter mode for 1000X link up

jane wu
Prodigy 10 points
Other Parts Discussed in Thread: DP83869EVM, DP83869

hello,

  we want to design DP83869evm to send data but not to receive data using fiber 1000BaseX. DP83869evm have work on the media converter mode  and have disabled atuo-negotiation by strap option.  if fiber rx is not connected with fiber cable, we see the LED_2 is off and FX_STS[2] is link down. so if sfp rx is not connected with fiber cable , how to operate in 1000BASE-X through the register settings for 1000base-x link up?  In the “DP83869 1000Base-X Link Detection”， if  Serdes Synchronization status bit (0x4F[8]) is set，the phy may achieve a successful 1000Base-X link-up, so how can i have SerDes synchronization? 

regards,

 jane

  • 0
    TI__Genius 16030 points

    Hello Jane,

    You will have to connect all the fiber pins for link-up to happen. Is your goal not to send the received data to MAC?

    --

    Regards,

    Vikram

  • 0 in reply to Vikram Sharma
    Prodigy 10 points

    we just want to connect tx->rx one fiber cable to send data but not receive data, can we access extended registers  to force fiber link up? or can we choose other operational modes of DP83869HM to make it ?

  • 0 in reply to Vikram Sharma
    Prodigy 10 points

    we just want to connect tx->rx one fiber cable to send data but not receive data, can we access extended registers  to force fiber link up? or can we choose other operational modes of DP83869HM to make it ?

  • 0 in reply to jane wu
    TI__Genius 16030 points

    I will check and get back if it can be supported by register config and how.

    --

    Regards,

    Vikram

  • 0 in reply to Vikram Sharma
    Prodigy 10 points

    hi, Vikram

    thanks for your replying. i heard some other phy vendors can force fiber link up through extended register config when Fiber RX is not connected with fiber. So please help us to check whether to design out our goals by register config. we are looking forward to your reply. thank you.

    Jane

    regards

  • 0 in reply to jane wu
    TI__Genius 16030 points

    Hello Jane,

    We found a mode which may work for your requirements. But in this mode the data sent by MAC to the Fiber side will also gets transmitted back to MAC. Is that ok for your application? May be MAC can be configured to ignore this incoming data?

    --

    Regards,

    Vikram

  • 0 in reply to Vikram Sharma
    Prodigy 10 points

    hello, Vikram,

    thank you for your help very much,. i think that mode you pointed out may help for our requirements and  be useful  for us. please tell us how to configure and make it for  DP83869evm. thank you very much. we are looking forward to your help.

    regards,

    jane

  • +1 in reply to jane wu
    TI__Genius 16030 points

    Hello Jane,

    Sorry for the delay. I was hoping to test it on EVM myself but I did not get access to the lab because of Covid situation in my area. Do you already have an EVM? If yes, then you may confirm the functionality at your end by following register settings :

    Set reg<0x00d4> bit[15] = 1 to enable an internal loopback

    Write reg<0x001F> = x4000 to do a soft restart and then start the data transmission.

    --

    Regards,

    Vikram

  • 0 in reply to Vikram Sharma
    Prodigy 10 points

    Hi  Vikram,

    thank you for your help. i have  made it based on the above register settings and confirmed your suggestion and the register config on  DP83869evm.

    can the PHy be configured to ignore this incoming back data when phy transmits data to others ? we are looking forward to your reply. thank you.

    regards,

    Jane

     

  • 0 in reply to jane wu
    TI__Genius 16030 points

    Hello Jane,

    Is the other side of 869 connected to Rgmii or is 869 here used in media converter mode (cu on another side)?

    --

    Regards,

    Vikram

  • 0 in reply to Vikram Sharma
    Prodigy 10 points

    869 here is used in media converter mode.   The other side of 869 is connecter to one fiber device  and the 869 transmits data to the  fiber device with one tx->rx fiber cable. so can the 869 be configured to ignore the transmited back data when the  869 enables an internal loopback and transmits data to other fiber device？

  • 0 in reply to jane wu
    TI__Genius 16030 points

    Hello Jane,

    You mentioned earlier that device on the other side can ignore the incoming packets due to internal loopback. Is that not true? If possible , I suggest you may go with that solution. I am checking with team if there is a register in PHY to stop sending the internal loopback data further but as these are not visible registers so finding the same may take time (if at all available).

    --

    Regards,

    Vikram