描述

General Description: In A1.5 a new form of OFFSET constraint is permitted with the

following syntax:

TIMEGRP "group" OFFSET={IN | OUT} offset_time [units] {BEFORE | AFTER} NET

["clk_net"] [TIMEGRP "reggroup"];

For example:

TIMEGRP INPUT_PADS OFFSET = IN 20 BEFORE CLK;

Using the Timing Analyzer GUI, the Disable Constraints Dialog box (Path Filters ->

Timing Constraint Filters -> Disable Timing Constraints) cannot be used to select

and disable timing constraints of the above type.

解决方案

This is fixed in M1.5i and Service Packs.

A current workaround for this problem requires hand editing the PCF file.

Open the DESIGN.PCF file in a text editor and comment out the constraint that you

wish to disable.

For example:

TIMEGRP INPUT_PADS OFFSET = IN 20 BEFORE CLK;

Would become:

#TIMEGRP INPUT_PADS OFFSET = IN 20 BEFORE CLK;

Save the PCF file and then re-run the Timing Analyzer. The commented out

constraints will no longer be analyzed.