UPGRADE YOUR BROWSER

We have detected your current browser version is not the latest one. Xilinx.com uses the latest web technologies to bring you the best online experience possible. Please upgrade to a Xilinx.com supported browser:Chrome, Firefox, Internet Explorer 11, Safari. Thank you!

AR# 24793

9.1.1 CPLDfit - "WARNING:Cpld:823 - Clock clk appearing in an OFFSET"

Description

In 9.1.1 CPLDfit, the following warning occurs if the clock signal in the offset constraint does not have a BUFG constraint applied to it, and the OFFSET constraint is not analyzed:

"WARNING:Cpld:823 - Clock clk appearing in an OFFSET timespec currently must be explicitly declared as a global clock input (BUFG) in your design. The OFFSET constraint referring to this clock will be ignored."

Solution

To work around this issue, the user can apply the BUFG constraint.

For example (in the UCF):

NET "clk" BUFG=CLK;

For further information on the BUFG constraint, see the Constraints Guide.

http://toolbox.xilinx.com/docsan/xilinx10/books/docs/cgd/cgd.pdf

AR# 24793
Date Created 09/04/2007
Last Updated 12/15/2012
Status Active
Type General Article