可调时钟

/**********************************************

工程名：可调时钟
模块名： clock

-----------------------------------------------
IO说明：
    clk:            50MHZ时钟
    key_in[3:0]:        四位独立按键
    seg_out[7:0]:        七段数码管段选
    seg_en[7:0]:        八个数码管位选
-----------------------------------------------
操作说明：
key[0] ：set键       调时/选位
key[1] ：inc键     增加 
key[2] ：sub键     减小
key[3] ：ok键      确认

1. 默认为计时状态，此时点下set键，进入调时状态
2. 此时秒位闪烁，此时点下 inc/sub键，即可调时
3：长按inc/sub键，进行快速调时，每秒加减10次
4：再点下set键,即可更换调时位
5：调完后按下ok键，恢复计时

------------------------------------------------

时间：2012年6月24日
作者：刘文武

***********************************************/
module clock(
    clk,    
    key_in,
    seg_out,
    seg_en
);


input clk; 
input [3:0] key_in;    
output [7:0] seg_out; 
output [7:0] seg_en;

//时间寄存器
reg [5:0] min,sec;    
reg [4:0] hour;

//a时    b分   c秒
//1十位      2个位
reg [31:0] a1,a2,b1,b2,c1,c2;


reg clk_1khz ;          //用于数码管扫描
reg clk_10hz;           //用于更新时间数据
reg clk_1_2hz;          //用于数码管闪烁

reg [7:0] seg_out ;     //数码管段选
reg [7:0] seg_en;       //数码管位选

reg state;              //状态位，计时为0，调时为1
reg [7:0]en_buf;        //en缓冲
reg [2:0] set_pos;      //调时位：{时,分,秒}
reg [3:0] key_buf;      //读键缓冲


//寄存器初始化
//----------------------------------------
initial
 begin
      count <= 24'b1 ;
      set_pos <=3'b001;
      en_buf <= 8'b1111_1110;
      seg_out <= 8'b1111_1111 ;
 end

//分频
//------------------------------------------
reg [24:0] count ;

always @ (posedge clk )
begin

 if( count == 25000000 ) count <= 1 ;    
 else count <= count + 1'b1;

if(count % 12500000 == 0 )   clk_1_2hz <= ~ clk_1_2hz;      //1_2HZ             
if(count % 2500000 == 0 )    clk_10hz <= ~ clk_10hz;        //10HZ
if(count % 25000 == 0 )      clk_1khz <= ~ clk_1khz;        //1kHZ
        
end


//数码管扫描
//------------------------------------------
always @ (posedge clk_1khz)
begin
 
// 计算时间位    
    a1<=hour/10;
    a2<=hour%10;
    b1<=min/10;
    b2<=min%10;
    c1<=sec/10; 
    c2<=sec%10;
//动态扫描
    seg_en<=en_buf;
    case (en_buf)
            //在调时状态下，该调试位为真，且1/2Hz时钟到来时，该数码管灭，实现闪烁效果
    8'b1111_1110 :   seg_out <= (state && set_pos[0]&& clk_1_2hz) ? 8'b1111_1111:zimu(a1);        
    8'b1111_1101 :   seg_out <= (state && set_pos[0] && clk_1_2hz) ? 8'b1111_1111: zimu(a2);
    8'b1111_1011 :   seg_out <= 8'b1011_1111;    //显示"-"
    8'b1111_0111 :   seg_out <= (state && set_pos[1] && clk_1_2hz) ? 8'b1111_1111:zimu(b1);
    8'b1110_1111 :   seg_out <= (state && set_pos[1] && clk_1_2hz) ? 8'b1111_1111:zimu(b2);
    8'b1101_1111 :   seg_out <= 8'b1011_1111;    //显示"-"
    8'b1011_1111 :   seg_out <= (state && set_pos[2] && clk_1_2hz) ? 8'b1111_1111:zimu(c1);
    8'b0111_1111 :   seg_out <= (state && set_pos[2] && clk_1_2hz) ? 8'b1111_1111:zimu(c2);
    default :    en_buf <=  8'b1111_1110;
    endcase
    //位选寄存器环形移位
    if(en_buf == 8'b0111_1111)    en_buf  <=  8'b1111_1110;
    else    en_buf  <= ~( ( ~en_buf ) << 1 );
            
end 


//按键消抖
//-----------------------------------------------
reg [19:0] key_count;

always @ (posedge clk)
begin
 if(key_in != 4'b1111)    //判断是否有键按下
 begin
    key_count <= key_count+1'b1;//当检测到有键按下，计数器加1
    key_buf <= 4'b1111;//此时延时尚未达到，所以输出为高

    if(key_count>=20'd1000000)
    begin
    key_count<=20'd1000001;//当达到延时200us（50MHZ）时，锁存key-count值
    key_buf <= key_in; //此时延时达到200us，输出为低
    end
 end
 else 
 begin
     key_buf <= 4'b1111; //当没有键按下时， 输出为高
     key_count <= 1'b0; //计数器清0
 end

end

//模式选择
//---------------------------------------------------
reg [3:0] count2;

always @ (posedge clk_10hz)
begin

        if(state == 0)
            begin
                //计时状态下，检测到set键按下，转为调时模式
                if(key_buf[0]==0) state <= 1'b1;
             
             
                if(count2==4'd9) 
                begin
                    count2<=4'b0;
                    //0.1s * 10 = 1s
                    timerun(sec,min,hour);
                end            
                else count2<=count2+1'b1;
            end
        else timeset(sec,min,hour,set_pos,key_buf);
    end


 //取字模函数
 //---------------------------------------------------

function [7:0] zimu;
    input [3:0]num;
    begin
    case(num)
        4'b0000:         zimu = 8'b1100_0000;    // "0"        
        4'b0001:         zimu = 8'b1111_1001;    // "1"
        4'b0010:         zimu = 8'b1010_0100;    // "2"
        4'b0011:         zimu = 8'b1011_0000;    // "3"
        4'b0100:         zimu = 8'b1001_1001;    // "4"
        4'b0101:         zimu = 8'b1001_0010;    // "5"
        4'b0110:         zimu = 8'b1000_0010;    // "6"
        4'b0111:         zimu = 8'b1111_1000;    // "7"
        4'b1000:         zimu = 8'b1000_0000;    // "8"
        4'b1001:         zimu = 8'b1001_0000;    // "9"
        default :        zimu = 8'bx;           //不确定
    endcase    
    end

endfunction

//计时任务
//------------------------------------------------
task timerun;
inout [5:0] sec,min;
inout [4:0] hour;
begin
if(sec==6'd59)
begin
    sec<=6'b0;
    if(min==6'd59)
    begin
        min<=6'b0;
        if(hour == 5'd23)
            hour<=5'b0;
        else
            hour<=hour+1'b1;
    end
    else
    min<=min+1'b1;
end
else
sec<=sec+1'b1;
end
endtask    


//调时任务
//------------------------------------------------
task timeset;

inout [5:0] sec,min;
inout [4:0] hour;
inout [2:0] set_pos;
input [3:0] key_buf;

begin

if(key_buf[0]==0)//按下set键，调试位左移，时<-分<-秒
    begin
        if(set_pos==3'b100) set_pos<=3'b001;
        else set_pos<=set_pos<<1;
    end
    else if (key_buf[1]==0)//按下inc键，调试位+
    begin
    
        case(set_pos)
        3'b100: begin if(sec==6'd59) sec<=6'd0; else sec<= sec+1'b1;        end    //秒+
        3'b010: begin if(min==6'd59) min<=6'd0; else min<= min+1'b1;        end    //分+
        3'b001: begin if(hour==5'd23) hour<=5'd0; else hour<= hour+1'b1;    end    //时+
        default:;
        endcase
    end
    else if (key_buf[2]==0)//按下sub键，调试位-
    begin
        case(set_pos)
        3'b100: begin if(sec==6'd00) sec<=6'd59; else sec<= sec-1'b1;        end    //秒-
        3'b010: begin if(min==6'd00) min<=6'd59; else min<= min-1'b1;        end    //分-
        3'b001: begin if(hour==5'd00) hour<=5'd23; else hour<= hour-1'b1;    end    //时-
        default:;
        endcase
    end
    else if (key_buf[3]==0)//按下ok键，退出调时模式
        state<= 1'b0;

end
endtask


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

endmodule