Description

Solution

In normal mode, the CDR (Clock and Data Recovery) is locked to incoming data. In some cases (i.e., when the receiver is used as a simple oversampler, or when NIDRU is needed), the CDR must be locked to local oscillator.

To lock the CDR to the local reference clock, read-modify-write through the DRP interface and set RX_CDR_CTRL2_LANE[7] = '1'.
This overrides the Phase Interpolator code.

The recovered clock will now be locked to thelocal reference clock.

References:

Dynamically Programmable DRU for High-Speed Serial I/O Application Note (XAPP875):
http://www.xilinx.com/support/documentation/application_notes/xapp875.pdf