Creating Timing Constraints with Constraints Editor

ISE

This process allows you to specify timing constraints for your design in a User Constraints File (UCF) using the Constraints Editor. You can specify timing constraints for individual nets or paths in your design, or you can specify global constraints. Timing constraints help you to reach your performance objectives by placing logic closer together, so that shorter routing resources can be used. In addition, you can use the Timing Ignore (TIG) constraint for those timing paths that should not be constrained.

Note For more information on constraints, see the Constraints Guide. For information on timing strategies, see Timing Constraints Strategies.

To Create Timing Constraints with Constraints Editor

In the Design panel, select Implementation from the Design View drop-down list.
In the Hierarchy pane, select the top module .
In the Processes pane, run the Translate process.
Note The translate process creates an NGD file required to run the Constraints Editor.
In the Hierarchy pane, select the top module or the associated UCF file.
Note Project Navigator will automatically create a UCF file for you if one does not exist in the project.
In the Processes pane, expand User Constraints, and double-click Create Timing Constraints.

The UCF opens in the Constraints Editor, which allows you to create, edit, and remove constraints. The state of your design goes out-of-date when you edit and save the UCF. Run the Translate process to update your design with the new or updated constraints.

Note For more information on using the Constraints Editor, see the Constraints Editor Help. In the Help Viewer, click the Synchronize TOC button

to view all related Help topics.

After running this process, you can do any of the following:

Synthesize your design.
Implement your design.