The followingwarningsare issuedduring Translate:
"WARNING:ConstraintSystem:119 - Constraint < net "xon_gen" LOC = AE9; >[./top_spaui_host_xaui.ucf(24)]: This constraint cannot be distributed fromthe design objects matching 'NET "xon_gen"' because those design objects do not contain or drive any instances of the correct type.
"WARNING:ConstraintSystem:203 - A target design object for the Locate constraint '< net "xon_gen" LOC = AE9; > [./top_spaui_host_xaui.ucf(24)]' could not befound and so the Locate constraint will be removed."
How can I solve this problem?
These warnings are issued because the "xon_gen" pin does not drive an IBUF, but drives the FPGA fabric directly (as shown in the following screenshot from the PlanAhead tool). NGDBuild does not find the IBUF component and issues the warnings.
Tosolve this problem, make sure the I/O buffer insertion is enabled globally, or for the specific pin, when you synthesize the design.