一、實驗任務

使用開發(fā)板上的四個按鍵控制四個LED燈。按下不同的按鍵時，四個LED燈顯示不同效果。本實驗是在EP4CE6F17C8開發(fā)板上實現(xiàn)，仿真請用modelsim Altera

二、系統(tǒng)框圖

三、代碼實現(xiàn)

module key_led (
    input clk,                      //時鐘周期
    input rst_n,                    //復位信號
    input [3:0] key ,               //4個按鍵，提供4個位寬
    output reg [3:0] key_led        //4個led燈，提供4個位寬
);
reg [1:0] state;                    //兩位寬的狀態(tài)寄存器，存儲4個狀態(tài)
reg [25:0] cnt_1s;                  //存儲1s的寄存器


parameter MAX_1s = 26'd49_999_999;//1s的時鐘周期


//1s計數(shù)器
always @(negedge rst_n or posedge clk) begin
    if (!rst_n) begin
        cnt_1s <= 26'd0;
    end
    else if (cnt_1s == MAX_1s) begin
        cnt_1s <= 26'd0;
    end
    else begin
        cnt_1s <= cnt_1s + 26'd1;
    end
end

//狀態(tài)每隔1s進行跳轉(zhuǎn)
always @(negedge rst_n or posedge clk) begin
    if (!rst_n) begin
        state <= 2'd0;
    end
    else if (cnt_1s == MAX_1s) begin            //每隔1s進入下一個狀態(tài)
        state <= state + 2'd1;
    end
    else begin
        state <= state;
    end
end

//不同按鍵不同led燈閃爍方式
always @(negedge rst_n or posedge clk) begin
    if (!rst_n) begin
        key_led <= 4'b0000;
    end
    else if (key[0] == 0) begin            //key0鍵按下,從右往左流水燈
        case (state)
            2'd0: key_led <= 4'b0001;
            2'd1: key_led <= 4'b0010;
            2'd2: key_led <= 4'b0100;
            2'd3: key_led <= 4'b1000;
            default: key_led <= key_led ;
        endcase
    end
     else if (key[1] == 0) begin            //key1鍵按下，從左往右流水燈
        case (state)
            2'd0: key_led <= 4'b1000;
            2'd1: key_led <= 4'b0100;
            2'd2: key_led <= 4'b0010;
            2'd3: key_led <= 4'b0001;
            default: key_led <= key_led ;
        endcase
    end
     else if (key[2] == 0) begin            //key2鍵按下，led燈閃爍
        case (state)
            2'd0: key_led <= 4'b1111;
            2'd1: key_led <= 4'b0000;
            2'd2: key_led <= 4'b1111;
            2'd3: key_led <= 4'b0000;
            default: key_led <= key_led ;
        endcase
    end
     else if (key[3] == 0) begin            //key3鍵按下，燈常亮
        case (state)
            2'd0: key_led <= 4'b1111;
            2'd1: key_led <= 4'b1111;
            2'd2: key_led <= 4'b1111;
            2'd3: key_led <= 4'b1111;
            default: key_led <= key_led ;
        endcase
    end
    else begin
        state <= state;
    end
end



endmodule

仿真代碼：

`timescale 1ns/1ns
module key_led_tb (
);
    reg clk;
    reg rst_n;
    reg [3:0] key;
    wire [3:0] key_led;

    parameter MAX_1s = 9;
    parameter CYCLE = 20;

    always #(CYCLE/2) clk <= ~clk;

    initial begin
        clk = 1'b0;
        rst_n = 1'b0;
        #(CYCLE);
        rst_n = 1'b1;
        key = 4'b1111;
        #(4*(MAX_1s + 1)*CYCLE);  //4個state的時間
        key = 4'b1110;
        #(4*(MAX_1s + 1)*CYCLE);  
        key = 4'b1101;
        #(4*(MAX_1s + 1)*CYCLE);  
        key = 4'b1011;
        #(4*(MAX_1s + 1)*CYCLE);  
        key = 4'b0111;
        $stop;
    end


    key_led  #(.MAX_1s(MAX_1s))u_key_led(
        .clk(clk),
        .rst_n(rst_n),
        .key(key),
        .key_led(key_led)
    );


    
endmodule

四、引腳分配

五、總結(jié)

注意：該實驗并未進行按鍵消抖，需一直按著按鍵才能讓該按鍵所操控的led變化功能實現(xiàn)。文章來源地址http://www.zghlxwxcb.cn/news/detail-737855.html

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