Manually applied Clock Data Recovery in Arria II GX

Hi,

To use the CDR of the transceiver channel, you would need to instantiate ALTGX instance to access and control the transceiver blocks including CDR. By the way, if I remember it correctly, the minimum data rate supported by Arria II GX transceiver is ~600Mbps which is much higher that your 20.8Mbps. You might want to try using oversampling to meet the transceiver minimum data rate. Also, the CDR is design to work with differential signaling. You would need to perform hardware to verify if the CDR can work with your single ended signaling.