What is a multicycle path?
From PDVerse STA Mentor Guide · pdVerse Mentor Guide
Short Answer
A multicycle path is a path where the design's intended behavior allows the data more than a single clock cycle to travel from its launching flop to its capturing flop, rather than the default assumption of exactly one cycle.
Example
You mark this kind of relaxed timing intent using set_multicycle_path, one of the timing exception commands alongside set_false_path, set_max_delay/set_min_delay, and set_clock_groups.
Why It Matters
By default, STA assumes every path must complete within a single clock cycle. If your design intentionally lets some slower operation take two or more cycles, you must tell the tool that explicitly, or it will flag a path as failing setup when it's actually working exactly as designed.
Command
set_multicycle_pathMentor Note — Common Mistake
Don't leave a genuinely multicycle path unmarked and just try to 'fix' the reported violation by speeding up logic. If the extra cycles were part of the design's real intent, the correct fix is declaring the exception, not needlessly optimizing the path.
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