Answers Database
Timespec constraints: UCF/NCF PERIOD constraints are not written correctly in the PCF file
Record #7197
Product Family: Software
Product Line: Other
Product Part: UCF File
Problem Title:
Timespec constraints: UCF/NCF PERIOD constraints are not written correctly in the PCF file
Problem Description:
Urgency: Standard
Problem Description:
In M1.5i, when the following timing constraints are entered in the UCF or NCF file, they
are not written correctly into the PCF file.
NET clka TNM_NET = A;
NET clkb TNM_NET = B;
TIMESPEC TS1 = PERIOD A 100 Mhz;
TIMESPEC TS2 = PERIOD B TS1/2;
These timespecs would become the following in the PCF file in M1.5i:
TS1 = PERIOD A 10 ns;
TS2 = PERIOD B TS1/2;
Note that TS2 should have been 50 Mhz(20ns), however it's getting written
as 5 nS.
In 2.1i, the correct Timespecs are written in the PCF file:
TS1 = PERIOD A 10 ns;
TS2 = PERIOD B TS1 * 2;
Solution 1:
Due to the changes in 2.1i, the existing m1.5i timespecs will give you
the wrong behavior in 2.1i. The users only need to make appropriate
changes in the UCF file to compenstate this problem.
This problem only exists when the Keyword PERIOD is used. A FROM-TO
spec in terms of frequency has always been handled properly, and base specs
in terms of delays do not cause problems.
End of Record #7197 - Last Modified: 08/04/99 11:33 |
