序列檢測101

設計一個101序列檢測器。要畫出狀態轉移圖，寫verilog，並仿真測試。

 使用Moore狀態機進行序列檢測，狀態轉移圖如下：

 

 

---

module seq_101(
                clk,
                rst_n,
                data_in,
                data_out
                );
    input clk;
    input rst_n;
    input data_in;
    output reg data_out;
    
    localparam IDLE=4'b0001,s1=4'b0010,s2=4'b0100,s3=4'b1000;
    //state change
    reg [3:0]current_state;
    reg [3:0]next_state;
    always@(posedge clk or negedge rst_n)
        if(!rst_n)
            current_state<=IDLE;
        else
            current_state<=next_state;
    //next_state generate
    always@(*)begin
            case(current_state)
                IDLE:begin
                    if(data_in==1)
                        next_state=s1;
                    else
                        next_state=IDLE;
                end
                s1:begin
                    if(data_in==0)
                        next_state=s2;
                    else
                        next_state=s1;
                end
                s2:begin
                    if(data_in==1)
                        next_state=s3;
                    else
                        next_state=IDLE;
                end
                s3:begin
                    if(data_in==1)
                        next_state=s1;
                    else
                        next_state=IDLE;
                end
                default:next_state=IDLE;
                
            endcase
    end
    //
    always@(posedge clk or negedge rst_n)
    begin
        if(!rst_n)
            data_out<=0;
        else if(current_state==s3)
            data_out<=1;
        else
            data_out<=0;
    end
endmodule 

`timescale 1ns/1ns
module tb;
    reg clk;
    reg rst_n;
    reg data_in;
    wire data_out;
    reg [19:0]data_init;
    integer i;
    seq_101 seq_101(
                .clk(clk),
                .rst_n(rst_n),
                .data_in(data_in),
                .data_out(data_out)
                );
    initial clk=0;
    always #10 clk=~clk;
    
    initial begin
        rst_n=0;
        data_init=20'b1010_0101_0111_0010_1010;
        #200;
        rst_n=1;
        for (i=0;i<20;i=i+1)
            #20 data_in=data_init[i];
    end
endmodule