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DP83822IF: 100BASE-FX single-mode RX not working

Vaclav Vanc
Prodigy 20 points
Part Number: DP83822IF

Hello,

we are experiencing problem interfacing DP83822IF PHY to single-mode SFP optics transceiver. We are using “DP83822 EVM” kit with SPF port with Finisar FTLF1323P1BTR transceiver. PHY is connected to MAC over MII interface.

Problem is at RX side of transceiver/PHY. About half of packets are lost during transmission. TX side is working OK.

Transceiver is 100BASE-FX single-mode. We tried other multi-mode transceivers (Avago) and those were working fine.

For configuration we are using Bootstrap pins. (We are only enabling FX_EN bit).

Our hardware connection looks like this (Although we also tried different setups):

Do you have any idea where the problem might be or what else can we check?

Regards,

Vaclav Vanc

  • 0
    TI__Mastermind 23675 points
    Hi Vaclav,

    The DP83822 has a current mode line driver. It requires 0.1uF DC blocking caps on both the RD and TD pins because of the biasing.
    Please also have 49.9 ohm pull-up resistors on the TD and RD pins between the PHY and the DC blocking caps.

    Please see section 9.2.2 for a recommended configuration.
  • 0 in reply to Ross Pimentel
    TI__Mastermind 23675 points
    Hi Vaclav,

    Have you had a chance to look into the suggested termination?
    Also, can you please provide me a register dump? I would like to know the values of registers 0x0 to 0x1F and 0x467 and 0x468.
  • 0 in reply to Ross Pimentel
    Prodigy 20 points

    Hi Ross,

    we connected PHY and transceiver just like is described in section 9.2.2. (Blocking capacitors and pull-ups). But problem is still same. About half of packets are lost during transmission (Tested with ping command).

    Here is the register dump:

    0x00    0x3100    
    0x01    0x784D    
    0x02    0x2000    
    0x03    0xA240    
    0x04    0x0181    
    0x05    0x0000    
    0x06    0x0004    
    0x07    0x2001    
    0x08    0x0000    
    0x09    0x0000    
    0x0A    0x4100    
    0x0B    0x1000    
    0x0C    0x0000    
    0x0D    0x401F    
    0x0E    0x0000    
    0x0F    0x0000    
    0x10    0x2A05    
    0x11    0x0108    
    0x12    0x8200    
    0x13    0x0000    
    0x14    0x00FF    
    0x15    0x014B    
    0x16    0x0100    
    0x17    0x004D    
    0x18    0x0400    
    0x19    0x0021    
    0x1A    0x0000    
    0x1B    0x007D    
    0x1C    0x05EE    
    0x1D    0x0000    
    0x1E    0x0002    
    0x1F    0x0000    
    0x467    0x08C3
    0x468    0x0000    

    We also tried different single-mode transceivers (Avago) and those were working out of the box. So it seems there is some incompatibility between PHY and Finisar transceivers.

    Best Regards,

    Vaclav Vanc