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AR# 53350

ISE Simulator: ERROR:HDLCompiler:1654 - Instantiating <(null)> from unknown module <****>

Description

This article explains the cause of errors similar to the below and how to work around them.

Starting static elaboration
ERROR:HDLCompiler:1654 - "C:/Users/ppopescu/Desktop/hydra_PP/mixed_verilog_vhdl_example/sources/encapsulated_mixed_code.v" Line 20: Instantiating <(null)> from unknown module <dff_vhdl>
ERROR:Simulator:778 - Static elaboration of top level Verilog design unit(s) in library work failed 


Solution

This error is normally generated when a VHDL module has not been instantiated properly in the top level Verilog/VHDL file. 


As an example refer to the code below: 

module example(
    input clk,
    input in,
    output out
    );

 

wire q1d2;

 
dff_vhdl
   (
   .clock(clk),
   .data_in(q1d2),
   .data_out(out)
   );

endmodule

 

You can clearly see that the instance dff_vhdl is not properly declared. 

The instance name is missing. 

This will generate an Error similar to the following:

Starting static elaboration
ERROR:HDLCompiler:1654 - "C:/Users/ppopescu/Desktop/hydra_PP/mixed_verilog_vhdl_example/sources/encapsulated_mixed_code.v" Line 20: Instantiating <(null)> from unknown module <dff_vhdl>
ERROR:Simulator:778 - Static elaboration of top level Verilog design unit(s) in library work failed 

You need to correct the code as below and it will run correctly.

module example(
    input clk,
    input in,
    output out
    );
  
wire q1d2;
  
dff_vhdl dff_vhdl_instance   (
   .clock(clk),
   .data_in(q1d2),
   .data_out(out)
   );

endmodule
AR# 53350
Date Created 12/05/2012
Last Updated 07/25/2014
Status Active
Type General Article
Tools
  • ISE Design Suite - 14