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AR# 25030

LogiCORE SPI-4.2 (POS-PHY L4) Lite v4.2 - PAR timing error can be seen on OFFSET constraint

Description

When running PAR for Spartan3A, the following OFFSET timing constraints in the UCF may not meet timing specifications because the VALID number is not correct for frequency of 105 Mhz. The correct number should be 4.00 ns instead of 3.00 ns.  

 

OFFSET = IN -1.00 ns VALID 3.00 ns BEFORE RDClk_P TIMEGRP RD_DDR_R ; 

OFFSET = IN -5.50 ns VALID 3.00 ns BEFORE RDClk_P TIMEGRP RD_DDR_F ; 

OFFSET = IN -1.00 ns VALID 3.00 ns BEFORE RDClk_P TIMEGRP RC_DDR_R ; 

OFFSET = IN -5.50 ns VALID 3.00 ns BEFORE RDClk_P TIMEGRP RC_DDR_F ;

Solution

Changing the OFFSET timing constraints in the UCF file can resolve this issue: 

 

OFFSET = IN -1.00 ns VALID 4.00 ns BEFORE RDClk_P TIMEGRP RD_DDR_R ;  

OFFSET = IN -5.50 ns VALID 4.00 ns BEFORE RDClk_P TIMEGRP RD_DDR_F ;  

OFFSET = IN -1.00 ns VALID 4.00 ns BEFORE RDClk_P TIMEGRP RC_DDR_R ;  

OFFSET = IN -5.50 ns VALID 4.00 ns BEFORE RDClk_P TIMEGRP RC_DDR_F ;

AR# 25030
Date Created 09/04/2007
Last Updated 05/21/2014
Status Archive
Type General Article