nexys4ddr数码管动态扫描Verilog例程

题目：实现数码管动态扫描功能，将十六个开关的值以十六进制的方式在4个数码管上同时显示出来。

`timescale 1ns / 1ps

module top(
    clk, sw, seg, an
    );
       //FPGA时钟
     input [15:0] sw;       // 16位拨动开关，其中SW[0]可用于作为复位信号rst
      input  clk;      
     output [7:0] seg;      // 8段数码管驱动，低电平有效
     output [7:0] an;       // 8段数码管片选信号，低电平有效
     wire [31:0] data;      //待显示内容
     wire clk1000Hz, clk100Hz, clk10Hz, clk1Hz;//1000/100/10/1Hz的时钟
      FrequencyDivider U_FRQNCYDVD(clk, clk1000Hz, clk100Hz, clk10Hz, clk1Hz);//分频器
     SevenSegDisp U_DISP(clk1000Hz, sw,seg, an);

module FrequencyDivider (clk, clk1000Hz, clk100Hz, clk10Hz, clk1Hz);//分频器
    input  clk;              // 系统时钟
    output reg  clk1000Hz;  // 分频后的时钟1000Hz
    output reg  clk100Hz;   //分频后的时钟100Hz
    output reg  clk10Hz;    //分频后的时钟10Hz
    output reg  clk1Hz;     // 分频后的时钟1Hz
    parameter      N1000 = 50_000;          // 1000Hz的时钟,N=fclk/fclk_N
    parameter      N100 = 50_000_0;          // 1000Hz的时钟,N=fclk/fclk_N
    parameter      N10 = 50_000_00;          // 1000Hz的时钟,N=fclk/fclk_N
    parameter      N1 = 50_000_000;         // 1Hz的时钟,N=fclk/fclk_N
    reg [31:0]      counter1000, counter100, counter10, counter1;  /* 计数器变量，通过计数实现分频。
                                                当计数器从0计数到(N/2-1)时，
                                                输出时钟翻转，计数器清零 */
    always @(posedge clk)  begin              // 时钟上升沿
        if(counter1000==N1000) begin
            clk1000Hz <= ~clk1000Hz;
            counter1000 <= 32'h0;
        end            
        else 
            counter1000 <= counter1000 + 1;
    end
    
    always @(posedge clk)  begin              // 时钟上升沿
        if(counter100==N100) begin
            clk100Hz <= ~clk100Hz;
            counter100 <= 32'h0;
        end            
        else 
            counter100 <= counter100 + 1;
    end
    
    always @(posedge clk)  begin              // 时钟上升沿
        if(counter10==N10) begin
            clk10Hz <= ~clk10Hz;
            counter10 <= 32'h0;
        end            
        else 
            counter10 <= counter10 + 1;
    end
    
    always @(posedge clk)  begin              // 时钟上升沿
        if(counter1==N1) begin
            clk1Hz <= ~clk1Hz;
            counter1 <= 32'h0;
        end            
        else 
            counter1 <= counter1 + 1;
    end
endmodule

`timescale 20ms / 1ms
module SevenSegDisp(clk,sw,seg,an);
    input clk;
    input [15:0] sw;       // 16位拨动开关
    output [7:0] seg;      // 7段数码管驱动，低电平有效
    output [7:0] an;       // 7段数码管片选信号，低电平有效
   
    reg [1:0] q; 
    wire [3:0] data;
    initial
    begin
    q=2'b00; 
    end
//    Counter8 U_CNT(clk,q); 
    always @(posedge clk )  begin
          q<=q+1;
          if (q==2'b11) q= 2'b00;
          else  q =  q;
          end   
             
    Mem U_MEM (q,sw,data);
    Decoder3_8 U_D38(q, an);   //片选 
    SevenSegDecoder U_SSD1(data,seg);  //8段码
    

endmodule

`timescale 20ms / 1ms

module Mem (num,sw,data);
    input [1:0] num;
    input [15:0] sw;
    output [3:0] data;
    reg [3:0] mem [3:0];
//    initial
//    begin
//       assign sw=16'h0000;
//    end
     assign data = mem[num];
    always @(*) begin
        mem[0] = sw[3:0];
        mem[1] = sw[7:4];
        mem[2] = sw[11:8];
        mem[3] = sw[15:12];
    end
   
endmodule

`timescale 20ms / 1ms

module Decoder3_8(num, sel);
    input  [1: 0] num;       // 数码管编号：0~7
    output reg [7:0] sel;       // 7段数码管片选信号，低电平有效

    always @(num) begin
        case(num)
            3'd0: sel = #10000000 8'b11111110;
            3'd1: sel = #10000000 8'b11111101;
            3'd2: sel =  #10000000 8'b11111011;
            3'd3: sel =  #10000000 8'b11110111; 
            default: sel = 8'b11111111;
        endcase
    end

endmodule

module SevenSegDecoder(
    data, segments    
);
    input [3:0]  data;
    output [7:0]  segments;
    
    assign segments = {dp, cg, cf, ce, cd, cc, cb, ca};
    
    reg dp, cg, cf, ce, cd, cc, cb, ca;
    always @(data) begin
            case(data)
                4'h0: {ca, cb, cc, cd, ce, cf, cg, dp} = 8'b0000_0011;
                4'h1: {ca, cb, cc, cd, ce, cf, cg, dp} = 8'b1001_1111;
                4'h2: {ca, cb, cc, cd, ce, cf, cg, dp} = 8'b0010_0101;
                4'h3: {ca, cb, cc, cd, ce, cf, cg, dp} = 8'b0000_1101;
                4'h4: {ca, cb, cc, cd, ce, cf, cg, dp} = 8'b1001_1001;
                4'h5: {ca, cb, cc, cd, ce, cf, cg, dp} = 8'b0100_1001;
                4'h6: {ca, cb, cc, cd, ce, cf, cg, dp} = 8'b0100_0001;
                4'h7: {ca, cb, cc, cd, ce, cf, cg, dp} = 8'b0001_1111;
                4'h8: {ca, cb, cc, cd, ce, cf, cg, dp} = 8'b0000_0001;
                4'h9: {ca, cb, cc, cd, ce, cf, cg, dp} = 8'b0001_1001;
                4'ha: {ca, cb, cc, cd, ce, cf, cg, dp} = 8'b0001_0001;
                4'hb: {ca, cb, cc, cd, ce, cf, cg, dp} = 8'b1100_0001;
                4'hc: {ca, cb, cc, cd, ce, cf, cg, dp} = 8'b1110_0101;
                4'hd: {ca, cb, cc, cd, ce, cf, cg, dp} = 8'b1000_0101;
                4'he: {ca, cb, cc, cd, ce, cf, cg, dp} = 8'b0110_0001;
                4'hf: {ca, cb, cc, cd, ce, cf, cg, dp} = 8'b0111_0001;
                default: {ca, cb, cc, cd, ce, cf, cg, dp} = 8'b1111_1111;
            endcase
        end

endmodule

set_property -dict { PACKAGE_PIN E3    IOSTANDARD LVCMOS33 } [get_ports { clk }]; #IO_L12P_T1_MRCC_35 Sch=clk100mhz
#create_clock -add -name sys_clk_pin -period 10.00 -waveform {0 5} [get_ports {CLK}];

set_property -dict { PACKAGE_PIN J15   IOSTANDARD LVCMOS33 } [get_ports { sw[0] }]; 
set_property -dict { PACKAGE_PIN L16   IOSTANDARD LVCMOS33 } [get_ports { sw[1] }]; #IO_L3N_T0_DQS_EMCCLK_14 Sch=sw[1]
set_property -dict { PACKAGE_PIN M13   IOSTANDARD LVCMOS33 } [get_ports { sw[2] }]; #IO_L6N_T0_D08_VREF_14 Sch=sw[2]
set_property -dict { PACKAGE_PIN R15   IOSTANDARD LVCMOS33 } [get_ports { sw[3] }]; #IO_L13N_T2_MRCC_14 Sch=sw[3]
set_property -dict { PACKAGE_PIN R17   IOSTANDARD LVCMOS33 } [get_ports { sw[4] }]; #IO_L12N_T1_MRCC_14 Sch=sw[4]
set_property -dict { PACKAGE_PIN T18   IOSTANDARD LVCMOS33 } [get_ports { sw[5] }]; #IO_L7N_T1_D10_14 Sch=sw[5]
set_property -dict { PACKAGE_PIN U18   IOSTANDARD LVCMOS33 } [get_ports { sw[6] }]; #IO_L17N_T2_A13_D29_14 Sch=sw[6]
set_property -dict { PACKAGE_PIN R13   IOSTANDARD LVCMOS33 } [get_ports { sw[7] }]; #IO_L5N_T0_D07_14 Sch=sw[7]
set_property -dict { PACKAGE_PIN T8    IOSTANDARD LVCMOS18 } [get_ports { sw[8] }]; #IO_L24N_T3_34 Sch=sw[8]
set_property -dict { PACKAGE_PIN U8    IOSTANDARD LVCMOS18 } [get_ports { sw[9] }]; #IO_25_34 Sch=sw[9]
set_property -dict { PACKAGE_PIN R16   IOSTANDARD LVCMOS33 } [get_ports { sw[10] }]; #IO_L15P_T2_DQS_RDWR_B_14 Sch=sw[10]
set_property -dict { PACKAGE_PIN T13   IOSTANDARD LVCMOS33 } [get_ports { sw[11] }]; #IO_L23P_T3_A03_D19_14 Sch=sw[11]
set_property -dict { PACKAGE_PIN H6    IOSTANDARD LVCMOS33 } [get_ports { sw[12] }]; #IO_L24P_T3_35 Sch=sw[12]
set_property -dict { PACKAGE_PIN U12   IOSTANDARD LVCMOS33 } [get_ports { sw[13] }]; #IO_L20P_T3_A08_D24_14 Sch=sw[13]
set_property -dict { PACKAGE_PIN U11   IOSTANDARD LVCMOS33 } [get_ports { sw[14] }]; #IO_L19N_T3_A09_D25_VREF_14 Sch=sw[14]
set_property -dict { PACKAGE_PIN V10   IOSTANDARD LVCMOS33 } [get_ports { sw[15] }]; #IO_L21P_T3_DQS_14 Sch=sw[15]

##7 segment display

set_property -dict { PACKAGE_PIN T10   IOSTANDARD LVCMOS33 } [get_ports { seg[0] }]; #ca
set_property -dict { PACKAGE_PIN R10   IOSTANDARD LVCMOS33 } [get_ports { seg[1] }]; #cb
set_property -dict { PACKAGE_PIN K16   IOSTANDARD LVCMOS33 } [get_ports { seg[2] }]; #cc
set_property -dict { PACKAGE_PIN K13   IOSTANDARD LVCMOS33 } [get_ports { seg[3] }]; #cd
set_property -dict { PACKAGE_PIN P15   IOSTANDARD LVCMOS33 } [get_ports { seg[4] }]; #ce
set_property -dict { PACKAGE_PIN T11   IOSTANDARD LVCMOS33 } [get_ports { seg[5] }]; #cf
set_property -dict { PACKAGE_PIN L18   IOSTANDARD LVCMOS33 } [get_ports { seg[6] }]; #cg
set_property -dict { PACKAGE_PIN H15   IOSTANDARD LVCMOS33 } [get_ports { seg[7] }]; #dp

set_property -dict { PACKAGE_PIN J17   IOSTANDARD LVCMOS33 } [get_ports { an[0] }]; #an[0]
set_property -dict { PACKAGE_PIN J18   IOSTANDARD LVCMOS33 } [get_ports { an[1] }]; #an[1]
set_property -dict { PACKAGE_PIN T9    IOSTANDARD LVCMOS33 } [get_ports { an[2] }]; #an[2]
set_property -dict { PACKAGE_PIN J14   IOSTANDARD LVCMOS33 } [get_ports { an[3] }]; #an[3]
set_property -dict { PACKAGE_PIN P14   IOSTANDARD LVCMOS33 } [get_ports { an[4] }]; #an[4]
set_property -dict { PACKAGE_PIN T14   IOSTANDARD LVCMOS33 } [get_ports { an[5] }]; #an[5]
set_property -dict { PACKAGE_PIN K2    IOSTANDARD LVCMOS33 } [get_ports { an[6] }]; #an[6]
set_property -dict { PACKAGE_PIN U13   IOSTANDARD LVCMOS33 } [get_ports { an[7] }]; #an[7]