Forum Discussion
New ContributorHow long should rx_is_lockedtodata be asserted before a valid connection can ACTUALLY be assumed?
Hi,
If during the toggling, the rx_is_lockedtodata assertion duration is longer than 4us, you can try to workaround by monitoring the RX signal detect to ensure valid signal presence before you check on the CDR status. Note that you would need to enable 8b10b block to use RX signal detect. You will need to set the signal detect thresholds according to your specific setup. You may refer to the SATA/SAS recommended QSF assignments in the V series XCVR PHY IP user guide -> Cyclone V Transceiver Native PHY IP Core -> "Enable rx_std_signaldetect port" section for further details.
Please let me know if there is any concern. Thank you.
Best regards,
Chee Pin
Regular ContributorHi,
As I understand it, you have some inquiries related to the CDR lock to data. As I understand it from the CV device handbook, it says that after rx_is_lockedtodata asserted, if it stays asserted for 4us, then CDR should have successfully locked to the incoming data.
When there is no incoming data, the CDR will periodically attempt to lock data. When it is attempting this, the rx_is_lockedtodata will go high. If no valid incoming data, then the rx_is_lockedtodata will go low. This will continue to repeat which lead to observation rx_is_lockedtodata toggling.
Just would like to check with you if you are observing the high duration of rx_is_lockedtodata when there is no valid data is more than 4us?
Please let me know if there is any concern. Thank you.
Best regards,
Chee Pin
