設計一計數器計數0~999

設計一計數器計數0~999_4A037052_蘇偉諺

即三位數BCD計數器

=========================程式碼=======================

module cnt10(clk,reset,q,cin);

        input   clk,reset;

        output  [3:0] q;

        output cin;

        reg     [3:0] q;

        reg cin;

        wire    eq;

        assign  eq=(q==4'd9);

        always@(posedge clk or posedge reset)

                if(reset) begin

                        q=0;

                        cin=0;

                end

                else if(q==4'd9) begin

                                cin= #1 1;

                                q= #1 0;

                        end

                        else begin

                                q= #1 q+1'b1;

                                cin= #1 0;

                        end

endmodule

module cnt999(clk,reset,digit1,digit2,digit3);

        input clk,reset;

        output [3:0] digit1;

        output [3:0] digit2;

        output [3:0] digit3;

        wire cin1,cin2,cin3;

        cnt10   U1(clk,reset,digit1,cin1);

        cnt10   U2(cin1,reset,digit2,cin2);

        cnt10   U3(cin2,reset,digit3,cin3);

endmodule

======================測試平台======================

`timescale 1ns/100ps

`include "cnt10.v"

module  testcnt10;

        reg     clk,reset;

        wire    [3:0] g,i,k;

cnt999  U1(clk,reset,g,i,k);

initial clk=0;

always #10 clk=~clk;

initial begin

        #0      reset=1;

        #10     reset=0;

        #1000010        $finish;

        end

initial begin

         $dumpfile("testcnt10.vcd");

         $dumpvars;

         end

endmodule

=====================GTKWAVE之波形圖=================