AR# 10019: 12.1 Constraints - How do I apply a PERIOD constraint to a design?
12.1 Constraints - How do I apply a PERIOD constraint to a design?
How do I apply a PERIOD constraint to my design?
Basic Period Specification
Figure 1 - Basic Period Specification
The PERIOD constraint covers only paths between synchronous elements. Synchronous elements include FFs, LATCHs, and Synch RAMs (PADS are not synchronous elements). An example of the UCF specification is as follows:
Another way to write the previous PERIOD constraint is to use the TIMESPEC keyword. (This is the preferred method for describing clocks.) In the following example, the TNM creates a user-defined group, and the TIMESPEC defines the timing specifications on that group.