Constraint management is an important step of the design flow, and the Vivado Design Suite provides you the flexibility of adding new constraints into an existing constraint file, overwriting existing constraints, or creating a new constraints file to track design changes or complete missing constraints.
You have created a few timing exceptions for the design, but the exceptions exist only in memory and not on disk yet. You need to save the exceptions to the timing.xdc file.
- From the Sources window in Vivado, double-click timing.xdc under .
- Scroll to the bottom of the file and notice that the
set_false_path and set_multicycle_path constraints do not exist in the file.
This is also reflected in the Timing Constraints Editor as <unsaved_constraints>, as shown in the
following figure.
- Click the Save
Constraints button
or use the command from the main menu. - Click the Reload link in
the banner of the timing.xdc tab to reload the constraints file from disk.
Notice that the false path and multi-cycle paths are now visible in the
timing.xdc text file, as shown in the
following
figure.
Note: The Tcl variable
_xlnx_shared_i0 is automatically inferred by Vivado to share the same collection of
objects between multiple timing constraints.