Answers Database


M1.5i/2.1i: UCF priority


Record #5747

Product Family: Software

Product Line: FPGA Implementation

Product Part: Timing Analyzer

Product Version: 1.5i

Problem Title:
M1.5i/2.1i: UCF priority


Problem Description:
URGENCY: standard

GENERAL DESCRIPTION:
Can you place higher priorities on certain constraints in the ucf file?


Solution 1:

On path constraints, like FROM:TO or FROM:THRU:TO, the keyword 'Priority' is used on a constraint, w hich is covering the same path that another constraint is covering, like:
    TIMESPEC TS_01= FROM A TO B 10ns;
    TIMESPEC TS_02= FROM A TO B 20ns PRIORITY 1;

And there are priority among different constraints. The following shows which constraints have the highest priority down to the lowerest priority.

  Hightest	1. Timing Ignore (TIG)
		     2.  FROM:THRU:TO specs
		     3.  FROM:TO specs
  Lowest       4.  PERIOD specs




Solution 2:

2.1i priority among constraints is as follows:

Highest    1.  FROM:THRU:TO specs
		2.  FROM:TO specs
		3.  Specific OFFSET constraints (specific data IOB)
		4.  Group  OFFSET constraints (time group of dat IOB)
		5.  Global OFFSET constraints (for all data IOBs)
Lowest	  6.  ALLPATHS constraints (like PERIOD)





End of Record #5747 - Last Modified: 07/13/99 15:21

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