DP83869HM: Output of SOP & SON of DP83869

Hi Rajesh,

There should be expected symbol on the line eventhough there are no data transmitted in the copper side. SON and SOP should be independent to the copper side. Are you using SGMII to copper application or Fiber to Copper application?

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Regards,

Hillman Lin

Hello Hillman,

Thanks for replying!!

There should be expected symbol on the line even though there are no data transmitted in the copper side. SON and SOP should be independent to the copper side. Are you using SGMII to copper application or Fiber to Copper application?

Ans: We are using 100baseTX to 100baseFX configuration. Furthermore, both the NIC (ie PC) and DP838 are set to forced 100mbps full duplex, thus auto negotiation is disabled. 

Note:

Question to TI:

1. In what cases SOP/SON are supposed to transmit repeating 01 non stop stream ?

2. We see an MLT-3 like stream coming from the PC to dp838, but the output of SOP/SON is a continuous repeating 01 stream (which doesn’t match the input data in the MLT-3 stream). 

3. Why input doesn’t match output?

Kindly let me know ASAP

Thanks 

Rajesh R

Hi Rajesh,

I am not sure if I understand your question clearly. Could you help me to clarify some of my concern?

• Why are you trying to read the repeating 01 non stop stream? What is the root cause of the problems that making you reading the SOP/SON stream?
• What did you mean by input doesn't match output? What is the input and what is the output? 

Could you help me out on these concern.

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Thank you,

Hillman Lin

Hello Hillman,

Thanks for your reply!

Ans:

• We have a DP83869HM configured as 100mbps media converter. We see constant 0101 repeating sequence from SOP/SON. 
• We have connected an NIC to the DP chip via RJ45 connector to the TD pins of the DP chip. 
• The LED for the TD link is blinking, assuming that link partner is up. 
• We probed the TD pins, and we can see signal from the NIC in the form of MLT-3 encoded signal. This MLT-3 signal is not a repeating 0101 but rather a signal containing useful data; and we expect to see the same data stream as an NRZI signal out from SOP/SON. Instead, we get a repeating 0101 signal from SOP/SON no matter what is the input at TD pins. That is our issue. Thank you. 

 PFA attached input and output signal FYR

7041.Input & Output signal of DP83869.docx

Thanks

Rajesh R

Hi Rajesh,

We would like to help you to debug the problem. Could you help me out on this problem

• Is there a communication problems on the fiber side? Or is there some other issue? 
• Are you able to read the register 006E, 0C01, and 0001?

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Thank you,

Hillman Lin

Hello Hillman,

Thanks for your reply!

QA: Are you able to read the register 006E, 0C01, and 0001?

Ans: Below Image

Kindly check & confirm ASAP

Thanks

Rajesh R

Hi Rajesh,

For the register you send me, I saw a temporary link up on your copper side. This is actually a rare case. Could you send me a block diagram on your setup for further debug?

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Thank you,

Hillman Lin

Hello Hillman,

Thank you for your response and continued support. 

• Our need is a bidirectional conversion of 100mbps  MLT-3 to 100mbps NRZI (125mbps with line encoding). 
• This can be achieved via DP83869 100mbps media converter mode (ie. 100baseTX to 100baseFX) where we only need the electrical output of the NRZI. 
• The NRZI is needed in electrical form (not photonic). 
• The NRZI signal is further processed in our circuit ending with a TLV350x single ended output comparator which reproduces the original NRZI signal. 
• The single ended output of the comparator is then fed to THS4551 to take the single ended input and produce a +/- NRZI output that can be fed again to SIP SIN pins (as per the previously sent image). 
• The data sheet (and especially the evm document) shows a schematic with 50E split ground termination between SOP/SON and between SIP/SIN. 
• The termination worked very well producing a clean output across R129/R130 (see image in previous email). But when we connected the track between R129/R130 and SIP/SIN input pins, signal got distorted as if SIP SIN pins are drawing much current or something like that. 
• Without SIP/SIN connected, output is perfect. 
• We tried disconnecting R129/R130 while being connected to SIP SIN. No change. Still distorted output. 
• We tried different resistor values. Still, no change. 

Thanks

Rajesh 

Hi Rajesh,

I will discuss this internally and provide you an response later this week.

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Regards,

Hillman Lin

Hi Rajesh,

I am still having trouble on understanding your setup. Could you draw out a block diagram so that I can understand the question better?

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Thank you,

Hillman Lin