34--跑表

module paobiao(
input clk,
input clr,
input pause,
output reg [3:0]msh,msl,sh,sl,mh,ml
);

reg cn1,cn2;//cn1爲百分秒向秒的進位，cn2爲秒向分的進位
//百分秒進位
always @(posedge clk or negedge clr)begin
    if(!clr)begin
        {msh,msl}<=8'd0;
        cn1<=0;
    end
    else if(!pause)begin
        if(msl==4'd9)begin
            msl<=4'd0;
            if(msh==4'd9)begin
                msh<=4'd0;
                cn1<=1'b1;
            end
            else msh<=msh+1'b1;
        end
        else begin
             msl<=msl+1'b1;
             cn1<=1'b0;
             end
    end
    else {msh,msl}<={msh,msl};
end
//秒進位
always @(posedge cn1 or negedge clr)
begin
   if(!clr)begin
    cn2<=1'b0;
    {sh,sl}<=8'b0;
    end 
    else if(sl==9)begin
            sl<=4'd0;
        if(sh==4'd5)begin
            sh<=4'd0;
            cn2<=1'b1;
        end
        else sh<=sh+1'b1;
        end
    else begin 
        sl<=sl+1'b1;   
        cn2<=1'b0;
    end 

    end
//分計數，滿60自動清零
always @(posedge cn2 or negedge clr)begin
    if(!clr)begin
        {mh,ml}<=8'd0;
    end
    else if(ml==9)begin
        ml<=4'd0;
        if(mh==4'd5)
            mh<=4'd0;
        else mh<=mh+1'b1;
    end
    else ml<=ml+1'b1;
end
endmodule

`timescale 1ns/1ns 
module tb_paobiao();
reg clk;
reg clr;
reg pause;
wire[3:0]msh,msl,sh,sl,mh,ml;
paobiao u1(.clk(clk),.clr(clr),.pause(pause),.msh(msh),.msl(msl),.sh(sh),.sl(sl),.mh(mh),.ml(ml));
initial begin
clk<=1'b0;
clr<=1'b0;
pause<=1'b0;
#50 clr<=1'b1;
#1000 pause<=1'b1;
#100 pause<=1'b0;
end
always #5 clk<=~clk;


endmodule