I'm new FPGAs, and working through the "IntroToSpartanFPGABook" PDF.
I'm looking at the "constraints.ucf" file, and (because I'm lazy), it occurred to me that I could create one "constraints.ucf" file for my (Papilio) Megawin, which I can then use for all projects, without modification. Switch 1 will always be on the same wire.
This works ok, except that everything that I DON'T use generates a warning:
WARNING:PhysDesignRules:367 - The signal <switch_1_IBUF> is incomplete. The signal does not drive any load pins in the design.
I understand that it is 100% correct, I am not using that switch (or LED), but if I remove the declaration, I need to have a different constraint file for each project (commenting and uncommenting as I go).
Is there a way of saying the following:
NET led_0 LOC = "P3" | IOSTANDARD=LVTTL DontGenerateWarningsIfNotConnected;