AR# 22993

8.1i CPLDFit - Using the "Preserve unused I/O" option does not keep placeholder I/O from being removed from the design

Description

My design contains several I/O that are unconnected. Since they are not used in the design, the CPLDFit tools optimize them out. I use the "Preserve Unused I/O" option, but these I/O continue to be optimized away. How do I keep these I/O from being removed from the design?

Solution

To work around this problem, place pin location constraints on these unused I/O. This, in combination with the "Preserve Unused I/O" option, will allow these I/O to be retained through implementation.

This application of the pin location constraints should not be required, and it will be corrected in a future software version.

AR# 22993
Date 12/15/2012
Status Active
Type General Article