Differences Between XDC and UCF Constraints - 2024.1 English

The fundamental differences between XDC and UCF constraints are:

• XDC is a sequential language, with clear precedence rules.
• UCF constraints are typically applied to nets: XDC constraints are typically applied to pins, ports, and cell objects.
• UCF PERIOD constraints and XDC create_clock command are not always equivalent and can lead to different timing results.
• UCF by default does not time between asynchronous clock groups, while in XDC, all clocks are considered related and timed unless otherwise constrained (set_clock_groups).
• In XDC, multiple clocks can exist on the same object.