In the XACT tools location constraints for unbonded pads used
the syntax of "Uxx", where "xx" corresponded to the pad
location for the unbonded I/O.
In the M1 tools location constraints for unbonded pads has
been changed to the format "UNBxx".
To constrain an unbonded pad to a specific location in your
schematic design, add the "LOC=UNBxx" attribute to the UPAD
component on your schematic.
For example to constrain a unbonded pad to pad location 66 do
In order to constrain an unbonded pad to a specific location
in a user constraint file (.ucf), add the following line to
your UCF file:
NET "NetName" LOC = "UNBxx"
where "NetName" is the name of the net connected to the UPAD.