【流水灯】— 黑金程序+按位拼接方法

方法一：

黑金使用 计数器 来控制4个LED灯

计数器分别去表示1s、2s、3s、4s这几个时间，然后实现流水灯

//================================================================================
//  Revision History:
//  Date          By            Revision    Change Description
//--------------------------------------------------------------------------------
//  2017/7/19     meisq          1.0         Original
//*******************************************************************************/

`timescale 1ns / 1ps
module led_test
(
    input           clk,           // system clock 50Mhz on board
    input           rst_n,         // reset ,low active
    output          led1,          // led on core board
    output reg[3:0] led            // LED,use for control the LED signal on expansion board
);

assign led1 = led[0];

//define the time counter
reg [31:0]      timer;

// cycle counter:from 0 to 4 sec
always@(posedge clk or negedge rst_n)
begin
    if (rst_n == 1'b0)
        timer <= 32'd0;                     //when the reset signal valid,time counter clearing
    else if (timer == 32'd199_999_999)      //4 seconds count(50M*4-1=199999999)
        timer <= 32'd0;                     //count done,clearing the time counter
    else
        timer <= timer + 32'd1;             //timer counter = timer counter + 1
end

// LED control
always@(posedge clk or negedge rst_n)
begin
    if (rst_n == 1'b0)
        led <= 4'b0000;                     //when the reset signal active
    else if (timer == 32'd49_999_999)       //time counter count to 1st sec,LED1 lighten
        led <= 4'b0001;
    else if (timer == 32'd99_999_999)       //time counter count to 2nd sec,LED2 lighten
        led <= 4'b0010;
    else if (timer == 32'd149_999_999)      //time counter count to 3rd sec,LED3 lighten
        led <= 4'b0100;
    else if (timer == 32'd199_999_999)      //time counter count to 4th sec,LED4 lighten
        led <= 4'b1000;
end
endmodule

 方法二：

// ----------------------------

// 功能：流水灯

// 细节：每个灯每隔1秒闪一次。不需要按键控制，上电就开始跑

// ----------------------------

module liu_led
(

input Clk,
input Rst_n,
input  key_flag,

output reg [3:0]LED

);


reg     [25:0]    count;

always@(posedge Clk or negedge Rst_n)begin
if(Rst_n == 1'b0)
    count <= 26'b0;
    else if(count == 26'd49_999_999)
        count <= 25'b0;
//    else if(key_flag == 1'b1)
//        count <= 25'b0;
        else 
            count <= count + 25'd1;
            
end


always@(posedge Clk or negedge Rst_n)begin
if(Rst_n == 1'b0)
    LED <= 4'b1110; // 高电平灯灭
//    else if(key_flag == 1'b1)
else if(count == 26'd49_999_999)
        LED <= {LED[2:0],LED[3]}; //高3位和低4位拼接
        else 
            LED <= LED;

end


endmodule