The Vivado IDE allows you to use one or multiple constraint files. Using a single constraint file for the entire compilation flow seems convenient, but maintaining all constraints becomes challenging as design complexity increases. This often happens with designs that incorporate several IP cores or large blocks developed by different teams.
After importing timing and physical constraints, you can export them as a single file regardless of the number of source files or project/non-project mode.
Follow these steps to export constraints:
- Run the
write_xdccommand to write all constraints to the specified output file. The IDE writes the constraints in the same order you read them into your project or design. - (Optional) Use the
write_xdc -typecommand-line option to export a subset of constraints. You can choose timing, physical, or waiver constraints.
Recommended:
- Separate timing constraints and physical constraints into two distinct files.
- Keep constraints that are specific to a certain module in a separate file.
- Organizing constraints in this way improves manageability and clarity in your design.