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AR# 1521

syn2xnf : ERROR 220: Can't open file '__ffgen__.xnf'

Description

While running syn2xnf or xmake on a Synopsys generated design the
following error may occur :

syn2xnf : ERROR 220: Can't open file '__ffgen__.xnf'

Upon further investigation into the .sxnf file you
may find lines similar to :

SYM,MY_reg<0>,__FFGEN__,LIBVER=2.0.0

Solution

1

One possible cause of this is an incorrect .synopsys_dc.setup
file.

1. Verify you have the proper search paths in the the proper
order in the file. The search path order should be the
project directory, followed by the Xilinx library directory
followed by the Synopsys library directory.

2. Verify you have the correct libraries by comparing with
the output of synlibs.

synlibs (-dc or -fc) <part>
where -dc is for Design Compiler and
-fc is for FPGA Compiler

Example : synlibs -fc 4005e-3

3. Verify you have all the necessary environment parameters
by comparing with one of the example setup files located
in : $DS410/examples/synopsys directory.

2

A second possible cause of this error is descibing a
register in the HDL code which the targeting architecture
can not support.

For example, if you describe a flip-flop that has both
an asynchronous set and an asynchronous reset in an XC4000
design, Synopsys will create an __ffgen__ because there
is no corresponding primative to infer. The XC4000 family
registers have an asynchronous set or reset but not both
at the same time on the same register.

If this is the case, the HDL code needs to be modified
to accomodate the targeting architecture.
AR# 1521
Date Created 11/14/1996
Last Updated 11/08/2004
Status Archive
Type General Article