Xilinx Constraints Guide

Chapter 4: Xilinx Constraints
where
The group some_ffs contains flip-flops whose output net names adhere to one of the
rules shown in the following table.
Pattern Meaning
a* Starts with a
b? Contains two characters, the first of which is b
c*d Starts with c and ends with d
Defining Area Groups Using Timing Groups
For more information, see Defining From Timing Groups in the Area Group
(AREA_GROUP) constraint.
Timing Groups UCF Syntax Example One
TIMEGRP “newgroup"="existing_grp1" "existimg_grp2" ["existing_grp3" ...];
where
newgroup is a newly created group that consists of:
– existing groups created via TNMs
– predefined groups
– other TIMEGRP attributes
Timing Groups UCF Syntax Example Two
TIMEGRP “GROUP1” = “gr2” “GROUP3”;
TIMEGRP “GROUP3” = FFS except “grp5”;
XCF Syntax
XST supports TIMEGRP with the following limitations:
• Groups Creation by Exclusion is not supported
• When a group is defined on the basis of another user group with pattern matching:
– TIMEGRP TG1 = FFS (machine*);
Supported
– TIMEGRP TG2 = TG1 (machine_clk1*);
Not supported
Constraints Editor Syntax
For information on Constraints Editor and Constraints Editor syntax in ISE® Design
Suite, see the ISE Design Suite Help.
PlanAhead Syntax
For more information about using the PlanAhead software to create constraints, see
Floorplanning the Design in the PlanAhead User Guide (UG632). See PlanAhead in this
Guide for information about:
• Defining placement constraints
• Assigning placement constraints
• Defining I/O pin configurations
• Floorplanning and placement constraints
Constraints Guide
284 www.xilinx.com UG625 (v. 13.2) July 6, 2011