A default area group is not large enough to fit logic, which causes errors in MAP.
Example of a MAP report on a default PACE area group constraint:
No COMPRESSION specified for AREA_GROUP AG_u13
Number of Slices: 115 out of 100 - 115%
Number of Slices containing unrelated logic: 42 out of 100 - 42%
Number of Slice Flip Flops: 157 out of 200 - 78%
Total Number 4 input LUTs: 158 out of 200 - 79%
Number used as 4 input LUTs: 158
PACE defaults to a 25% area group padding estimation during a drag-and-drop operation. However, this estimation might still be insufficient for fitting the logic in the area group.
Increase the area group range. To modify the default area group padding in PACE, select Area -> Area Padding and uncheck it. Repeat this process to bring up the padding dialogue box, and increase the default value.
When you manually draw the area group constraint, increase the area group size.
If the unrelated logic packing indicated by the MAP report is not full, manually modify the UCF to increase the area group compression factor.
The basic UCF syntax is:
INST "X" AREA_GROUP=groupname
AREA_GROUP groupname RANGE=range
AREA_GROUP groupname COMPRESSION=percent
where "groupname" is the name assigned to the identified logical block instances in order to uniquely define a group.
The range defines the physical area in the same way that ranges are defined for the LOC constraint: for "groupname", using the appropriate syntax for the device. The percent value defines the compression factor for "groupname". The percent values can be from 0 to 100.
If the group does not have a RANGE, only 0 (no compression) and 1 (maximum compression) are meaningful. The mapper computes the number of CLBs in the group from the range and attempts to compress the logic into the percentage specified. Compression does not apply to TBUFs, block RAMs, or multipliers.