Using defparam

Parameter values can be changed in any module instance in the design with keyword defparam. Hierarchical name of the module instance can be used to override parameter values.

//Define a module hello-world

module hello-world;

parameter id-num = 0; //define a module identification number = 0

initial //display the module identification number

Sdisplay("Disp1aying hello-world id number = %dM, id-num);

Endmodule

//define top-level module

module top;

//change parameter values in the instantiated modules

//Use defparam statement

defparam wl.id-num = 1, w2.id-num = 2;

//instantiate two hello-world modules

hello-world wl0;

hello-world w2 ( ) ;

endmodule

Module hello-world was defined with a default id-num = 0. Though, when module instances wl  and w2 of the type hello-world are created, their id-num values are modified with defparam statement.

If we simulate above design, we would get the below output:

Displaying hello-world id number = 1

Displaying hello-world id number = 2

Multiple defparam  statements  can  appear  in  a  module.  Any parameter  can  be  overridden  with  the defparam statement.