Constraint Entry Overview
All constraints are entered in a User Constraint File (UCF)
Some synthesis tools allow entry of constraints
- Constraint files may be generated by the synthesis tools, or constraints may be written in output netlist
- Check the vendor interface
UCF file syntax is given in this chapter
One UCF file is defined per design
Timing constraints may also be defined in schematic
- Advantage: Easy entry for hierarchical blocks
- UCF files must have hierarchical net and component names
- Disadvantage: Not all constraints are supported
- See Libraries guide for schematic syntax and availability