An assignment that allows you to specify a timing requirement or other timing characteristic for the entire project or for individual entities, nodes, or pins. You can make individual and project-wide timing assignments with the Assignment Organizer command (Assignments menu). Alternatively, you can specify project-wide timing requirements and other timing settings with the Settings command (Assignments menu).
When you specify individual or project-wide timing requirements and use timing-driven compilation, the Fitter optimizes the placement of logic in the device to attempt to achieve the specified timing goals. After compilation, the Compilation Report shows whether the specified timing requirements were achieved.
The following tables list all available individual and project-wide timing assignments. Click the assignment name for more information about using the assignment.
| Assignment Name | Setting | Assignment Type |
|---|---|---|
| Clock Settings | <clock settings name> | Individual |
| Cut Off Clear and Preset Signal Paths | On | Off | Project-wide |
| Cut Off Feedback from I/O Pins | On | Off | Project-wide |
| Cut Off Read During Write Signal Paths | On | Off | Project-wide |
| Cut Paths between Unrelated Clock Domains | On | Off | Project-wide |
| Cut Timing Path | On | Off | Individual |
| Default Multicycle Hold | One | Same As Multicycle | Project-wide |
| Enable Multicycle | <number of clock cycles> | Individual |
| Enable Multicycle Hold | <number of clock cycles> | Individual |
| Enable Source Multicycle | <number of clock cycles> | Individual |
| Enable Source Multicycle Hold | <number of clock cycles> | Individual |
| External Input Delay | <delay value> | Project-wide and individual |
| External Output Delay | <delay value> | Project-wide and individual |
| fmax Requirement | <requirement value> | Project-wide |
| Ignore Clock Settings | On | Off | Project-wide |
| Include External Pin Delays in fmax Calculations | On | Off | Project-wide |
| Inverted Clock | On | Off | Individual |
| Minimum Delay Requirement | <delay value> | Individual |
| Multicycle | <number of clock cycles> | Individual |
| Multicycle Hold | <number of clock cycles> | Individual |
| Not a Clock | On | Off | Individual |
| Number of Source Nodes to Report | <value> | Project-wide |
| Run All Timing Analyses | On | Off | Project-wide |
| Source Multicycle | <delay value> | Individual |
| Source Multicycle Hold | <delay value> | Individual |
| tco Requirement | <requirement value> | Project-wide and individual |
| th Requirement | <requirement value> | Project-wide and individual |
| tpd Requirement | <requirement value> | Project-wide and individual |
| tsu Requirement | <requirement value> | Project-wide and individual |
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