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AR# 37853

ISE 12.2 Maplib - KEEPER constraint is not applied to the ports.


Below is a test case to check the use of KEEPER:

module test 

input clk, 
input en, 
inout [7:0] data, 
output [7:0] data1 

reg [7:0] cnt = 0; 
always @(posedge clk) 
cnt <= cnt + 1'b1; 

assign data = (data[0])?cnt: 8'bz; 
assign data1 = (en)?cnt:8'bz; 

An issue has been found where some 3-state ports did not have the KEEPER constraints applied.


This is a known issue which has been fixed in ISE 13.1.

To work around this issue, set XIL_MAP_NO_TRIM_REDUNDANT_KEEPER and rerun Map.

AR# 37853
Date 07/30/2014
Status Active
Type General Article
  • ISE Design Suite - 12.2
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