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AR# 14606

Virtex-II Pro RocketIO - How do I perform clock correction on a multiple comma sequence (rather than a single comma)?


The dedicated hardware for comma alignment will align only when a single comma is used. How do I set up the transceiver so that it aligns on a particular series of commas?


Here is a simple example scheme: connect RXCOMMADET to ENPCOMMAALIGN and ENMCOMMAALIGN.  


In this case, realignment will occur only in the presence of a burst of commas, with the first comma causing ENPCOMMAALIGN and ENMCOMMAALIGN to be asserted, and subsequent commas causing realignment. A single comma should not cause realignment in this case. 


Some experimentation may be needed to determine how long a burst of commas must be in order for realignment to occur reliably, but it is probable that four or more commas will be required.

AR# 14606
Date Created 08/29/2007
Last Updated 05/14/2014
Status Archive
Type General Article