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AR# 16904

6.1i XST - "WARNING:Xst:1887 - Unable to fit FSM <FSM_0> in BRAM"


Keywords: FSM, block, RAM, BRAM, MAP, XST

Urgency: Standard

General Description:
When the new XST feature "Map FSM to BRAM" is set, the following messages occur:

"WARNING:Xst:1887 - Unable to fit FSM <FSM_0> in BRAM
Selecting encoding for FSM_0 ..."

"EXCEPTION:Xdm:Block.c:1141:$Id: Block.c,v 1.14 2003/05/16 20:22:40 jdl Exp $ - Xdm_Exception: :DuplicateObjectFound object='In0' (XDM_PIN), parent='/top/RTL/top/currentState' (XDM_BLOCK)
FATAL_ERROR:Xst:Port_Main.h:127:1.13 - This application has discovered an exceptional condition from which it cannot recover. Process will terminate. To resolve this error, please consult the Answers Database and other online resources at http://support.xilinx.com. If you need further assistance, please open a Webcase by clicking on the "WebCase" link at http://support.xilinx.com."


You can use this new feature by turning off the "Generate RTL Schematic" as follows:

1. Right-click on the "Synthesize" process.
2. Select "Properties..."
3. Select the "Synthesis Options" tab.
4. Change "Generate RTL Schematic" to "No".
5. Select "OK".

This problem has been fixed in the latest 6.1i Service Pack, available at:
The first service pack containing the fix is 6.1i Service Pack 1.
AR# 16904
Date Created 03/20/2003
Last Updated 03/05/2006
Status Archive
Type General Article