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AR# 20295

10.1 Floorplanner - When using DISTRIBUTED (LUT) RAM in design, "Write RPM to UCF" function fails


When I am making one small design where I use Xilinx coregenlib DISTRIBUTED RAM core of any dimension, implement the design, open post-PAR Floorplanner, and try to create RPM through File->Write RPM to UCF with "Automatically Generate RPM in NGC Format" option checked, the following error occurs:  


"ERROR:NgdBuild:753 - Line 4 in 'D:/basheer/Exp1/dpram_rpm/dram_rpm.ucf': 

Could not find instance(s) 'INST/BU37' in the design. To suppress this error specify the correct instance name or remove the constraint." 


How can I solve this problem?


In the UCF file, Floorplanner is writing out constraints for instances that do not exist in the EDIF. 


For Example: 

INST "BU6" RLOC = "X0Y0" ; 

INST "BU6/RAM64X1S1" RLOC = "X2Y0" ; 

INST "BU6/RAM64X1S0" RLOC = "X3Y0" ; 

....... ....... 


The instance "BU6" is in the netlist, but not in the lower-level instances ("RAM64X1S1" and "RAM64X1S0"). The NGD file contains these instances, but not the EDIF.  


To work around this issue, simply remove the "BU*/RAM64S*" constraints from the UCF and run the NGDBuild command line. This will constrain the position of the RAM. However, it might ignore the RPM of the distributed RAM itself.

AR# 20295
Date Created 09/03/2007
Last Updated 05/16/2014
Status Archive
Type General Article