DS90UB940-Q1: Inquiry about the link error count register

Hello,

We are trying to design evaluation boards to use the DS90UB949-Q1 and DS90U940-Q1. We are planning to do EMC testing on the evaluation boards and the signal communication. We are trying to find a way to monitor the link status during EMC testing to understand if the signal is affected by the EMC disturbance. We did find the DS90U940-Q1 has a register 'link error count'. Would you help me to know if this register can be used to monitor the link communication status during EMC testing? But we do not find a register available within the DS90UB949-Q1. Would you help me to know if the DS90UB949-Q1 has this kind of register can be used? Thanks very much.

Best Regards

Zhisheng

Kailyn Chen：

Hello, there is no specified register which detects the EMC testing, usually we use the lock pin status for EMC testing to determine if there are FPD errors. 

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?? ?：

Thanks, Kailyn. So, for DS90UB949-Q1, the lock pin is recommended to be used. For DS90UB940-Q1, can the error count register be used? Appreciate your help.

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Kailyn Chen：

HI, the link error doesn't indicate the EMC  issue.

The link error meaning: The FPD-Link protocol creates packets (frames) to send over the high speed forward channel. These packets contain video data, clock bits, and other data including encoding bits. In this case the 940 packet structure contains 2 clocking bits per frame and a DCA bit which is for FPD-Link encoding. When each packet is received these specific bits can be checked against their expected value and if there is not a match, then an error will be flagged.