Answers Database

M1.5: Cannot TIMESPEC the TDO pin on XC4000E/X FPGAs.


Record #4161

Product Family:  Software

Product Line:  Merged Core

Problem Title:
M1.5: Cannot TIMESPEC the TDO pin on XC4000E/X FPGAs.


Problem Description:
Keywords:

Urgency: Standard

	     pad on XC4000E/X FPGAs. When time constraints are
	     applied that directly feed the TDO pin they are
	     reported "0 items analyzed, 0 timing errors
	     detected." in the timing report.


Solution 1:

You can trace the delay to the IOB pin, but you can not determine the delay in t
he IOB. This can be done in the Timing Analyzer by using the path filters to sel
ect the appropriate source and destination. The destination is the net driving t
he buffer connected to TDO.



End of Record #4161