General Description: How can I use the TIMESPEC part from my Xilinx library to specify global timing constraints when using Orcad Express?
In order for Express to recognize the TIMESPEC part, it must place a "dummy" pin in the netlist while compiling. However, you must remove this dummy pin (and any associated net) from the netlist before building/implementing your design, in order to avoid errors in XACTStep and M1. Follow these steps:
1.Place the TIMESPEC part and assign the appropriate Xilinx timing attributes as you would normally.
2.Compile the design with the Compile command.
3.If you are using XACTStep, open the resulting XNF, search for the string "TIMESPEC" and remove the line: PIN, dummy, I, dummy that immediately follows the TIMESPEC instance. For example:
Before: LCANET, 6 PROG, EXPRESS.EXE, 7.10, 01/28/98 PART, 5206PC84-5 SYM,u1,TIMESPEC,LIBVER=2.0.0 PIN, dummy, I, dummy EOF END