Cyclone V Device Handbook: Volume 2: Transceivers

ID 683586
Date 10/24/2018
Document Table of Contents Running Disparity Control

The 8B/10B encoder automatically performs calculations that meet the running disparity rules when generating the 10-bit code groups. The running disparity control feature provides user-controlled signals (tx_dispval and tx_forcedisp) to manually force encoding into a positive or negative current running disparity code group. When you enable running disparity control, the control overwrites the current running disparity value in the encoder based on the user-controlled signals, regardless of the internally-computed current running disparity in that cycle.

Note: Using running disparity control may temporarily cause a running disparity error at the receiver.