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AR# 10370

6.3i Modular Design - "ERROR:NgdBuild 604 (or 605) - No driver was found for logical net 'netname' for this modular design..." (Verilog)

Description

Keywords: translate, initial, ports, undefined, direction

Urgency: Standard

General Description:
During the modular design initial flow for my Verilog design, the following errors occur:

"ERROR:NgdBuild:605 - No load was found for logical net 'N_top2b' in this modular design. Ports with an undefined direction were found connected to the net. Please assign a direction to these ports."

"ERROR:NgdBuild:604 - No driver was found for logical net 'N_mod_c_out' for this modular design. Ports with an undefined direction were found connected to the net. Please assign a direction to these ports."

Solution

In modular design, when you instantiate a module in a design's top-level, the direction of the module ports must be declared.

If the direction of the ports is not declared in the top-level, NGDBuild cannot determine whether the ports are "input to" or "output from" the module.

For example:

Top ( ...);
input ...;
output ...;

// module_a instantiation and port map
module_a instance_a ( ...);

endmodule //End of top- level

//Declaration of module_a in top-level Verilog
module_a (...);
input ...;
output ...;
endmodule //End of module_a declaration
AR# 10370
Date Created 10/23/2000
Last Updated 02/06/2007
Status Archive
Type General Article