Other Parts Discussed in Thread: DS15BA101, SN65LVP20, DS90LV001
Hello there,
We would like to ask for help to debug the DP83869HM used as 100M media convertor.
For communication link we use two units of DP83869HM in 100M Media Convertor Mode (9.4.8.6, SNLS614B, p. 39) from layers: Copper to Fiber --> Fiber to Copper at 100M.
Setting of the DP83869HM is done through strap boot up only. (1.7, SNLA318, p. 9), verified then by reading out the registers.
A synchronization of TWO UNITs seems to work okay. No error observed.
The problem appears once communication is initiated. The synchronization is lost completely.
There is a problem once:
TWO DP83869HMs are used on both sides of layer conversion.
There is no problem once:
ONE DP83869HM is used on one side, a UNIT with a different PHY is used on the other side.
There are used exact same optical components and settings for both units no matter what PHY is used.
To test the communication Bit Error Rate Tester with RJ45 connections is used. We can monitor sent and received bit stream, test latency, jitter, BER, etc.
The signal detect feature is not used, DP83869HM SD pin is active low (grounded) to show always valid signal.
We observed that once we reduce received optical power on both units with DP83869HM, the synchronization and communication come back.
- Could you please explain whether there is some built in logic which the DP83869HMs may influence each other in this configuration?
- What could create increased optical power to the DP83869HM? (RX signals are LVDS)
- Why there is no problem once one unit is replaced with different PHY?
If needed we can share more information, schematics in PM etc.
Thank you a lot for help here.
Best Regards,
Michael
