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JC_FPGA's avatar
JC_FPGA
Icon for New Contributor rankNew Contributor
5 years ago

Cyclone V transceiver status rx_disperr and rx_errdetect inactive, even when unplugging SMA cable

I'm working on a Cyclone V design that has several transceivers. I've added error counters for the rx_disperr and rx_errdetect status ports. They run on the rrefclk clock domain coming out of the tra...
CheepinC_altera's avatar
CheepinC_altera
Icon for Regular Contributor rankRegular Contributor
5 years ago

Hi,


As I understand it, you have some inquiries related to the rx_disperr and rx_errdetect. Based on my experience, these signals will toggle when there is an 8b10b error occurs which might be due to signal integrity problem or data error. When the cable is disconnected, the CDR may lose lock and I am not sure if the 8b10b error status signal will still work.


Can you try with the following:


1. Enable the tx_forcedisp in Custom PHY. Then in user mode, assert this signal to forcefully change the running disparity. Ideally you should see rx_disperr asserts at the RX side.


2. Create a simple one channel test design with Native PHY and repeat similar test if can replicate the observation.


Please let me know if there is any concern. Thank you.