Question

Implement a 4x1 multipexer using behavioral modeling in verilog, also write its test bench.

Answer 1

Answer:-------------
4x1 multipexer using behavioral modeling in verilog:-------------------

module mux4X1( in,sel,out);
input [3:0]in;
input [1:0]sel;
output reg out;

always @(*)
   begin
       case(sel)
           2'b00: out=in[0];
           2'b01: out=in[1];
           2'b10: out=in[2];
           2'b11: out=in[3];
           default: out=1'b0;
       endcase
   end
endmodule

Test bench:-------
module mux4X1;

reg[3:0] in;
reg[1:0] sel;
wire out;

integer i;

mux4X1 my_mux( sel, in, out );

initial
begin
#1 $monitor("in = %b", in, " | sel = ", sel, " | out = ", out );

for( i = 0; i <= 15; i = i + 1)
begin
in = i;
sel = 0; #1;
sel = 1; #1;
sel = 2; #1;
sel = 3; #1;
$display("-----------------------------------------");
end

end
endmodule