4x4的矩阵键盘

1. 做矩阵键盘的预备条件：按键消抖。
2. 矩阵键盘的大体思路：
   如果会独立按键的话，相对来说只是多了一个行遍历，检测是出具体行数就对应出了坐标，即特定按键。
   独立按键原理图：
   初始每个键位都输出逻辑“1”，那个按键被按下去，该按键对应的接口输出逻辑“0”。松开又为“1”。
   矩阵键盘不过是原来一行现在变成了多行，处理办法就是从上到下依次给行接口置零，如果检测到有按键按下则重头开始遍历。具体可以采用状态机实现。
   矩阵键盘原理图：
   状态机
   
   按键消抖代码略

module  RowcontrollerAndValueout(
    input   clk,
    input   rst_n,
    inout   [3:0]list,
    output  reg [3:0]row,
    output  reg [15:0]  value
);

listpress       uut_listpress(//该模块为按键消抖处理
    .clk(clk),
    .rst_n(rst_n),
    .list(list),
    .press(press)//此接口引出的是处理后的list按键
);


wire[3:0] press;        //列按键按下键值，高电平有效

//状态机采样键值 
reg[3:0] nstate,cstate;
parameter K_IDLE = 4'd0;    //空闲状态，等待
parameter K_H1OL = 4'd1;    //key_h[0]拉低
parameter K_H2OL = 4'd2;    //key_h[1]拉低
parameter K_H3OL = 4'd3;    //key_h[2]拉低
parameter K_H4OL = 4'd4;    //key_h[3]拉低
parameter K_CHCK = 4'd5;    
    //状态切换
always @(posedge clk or negedge rst_n)
    if(!rst_n) cstate <= K_IDLE;
    else cstate <= nstate;

always @(cstate or press or list)
    case(cstate)    
        K_IDLE: if(press != 4'b0000) nstate <= K_H1OL;
                else nstate <= K_IDLE;
        K_H1OL: nstate <= K_H2OL;
        K_H2OL: if(list != 4'b1111) nstate <= K_IDLE;
                else nstate <= K_H3OL;
        K_H3OL: if(list != 4'b1111) nstate <= K_IDLE;
                else nstate <= K_H4OL;
        K_H4OL: if(list != 4'b1111) nstate <= K_IDLE;
                else nstate <= K_CHCK;
        K_CHCK: nstate <= K_IDLE;
        default: ;
    endcase

//-------------------------------------
//采样键值  
reg[3:0] new_value; //新采样数据
reg new_rdy;    //新采样数据有效

always @(posedge clk or negedge rst_n)
    if(!rst_n) begin
        row <= 4'b0000;
        new_value <= 4'd0;
        new_rdy <= 1'b0;
    end
    else begin
        case(cstate)    
            K_IDLE: begin
                row <= 4'b0000;
                new_value <= 4'd0;
                new_rdy <= 1'b0;        
            end
            K_H1OL: begin
                row <= 4'b1110;
                new_value <= 4'd0;
                new_rdy <= 1'b0;    
            end
            K_H2OL: begin
                case(list) 
                    4'b1110: begin
                            row <= 4'b0000;
                            new_value <= 4'd0;
                            new_rdy <= 1'b1;        
                        end         
                    4'b1101: begin
                            row <= 4'b0000;
                            new_value <= 4'd1;
                            new_rdy <= 1'b1;        
                        end         
                    4'b1011: begin
                            row <= 4'b0000;
                            new_value <= 4'd2;
                            new_rdy <= 1'b1;        
                        end                 
                    4'b0111: begin
                            row <= 4'b0000;
                            new_value <= 4'd3;
                            new_rdy <= 1'b1;        
                        end
                    default: begin
                            row <= 4'b1101;
                            new_value <= 4'd0;
                            new_rdy <= 1'b0;        
                        end
                endcase
            end
            K_H3OL: begin
                case(list) 
                    4'b1110: begin
                            row <= 4'b0000;
                            new_value <= 4'd4;
                            new_rdy <= 1'b1;        
                        end         
                    4'b1101: begin
                            row <= 4'b0000;
                            new_value <= 4'd5;
                            new_rdy <= 1'b1;        
                        end         
                    4'b1011: begin
                            row <= 4'b0000;
                            new_value <= 4'd6;
                            new_rdy <= 1'b1;        
                        end                 
                    4'b0111: begin
                            row <= 4'b0000;
                            new_value <= 4'd7;
                            new_rdy <= 1'b1;        
                        end
                    default: begin
                            row <= 4'b1011;
                            new_value <= 4'd0;
                            new_rdy <= 1'b0;        
                        end
                endcase
            end
            K_H4OL: begin
                case(list) 
                    4'b1110: begin
                            row <= 4'b0000;
                            new_value <= 4'd8;
                            new_rdy <= 1'b1;        
                        end         
                    4'b1101: begin
                            row <= 4'b0000;
                            new_value <= 4'd9;
                            new_rdy <= 1'b1;        
                        end         
                    4'b1011: begin
                            row <= 4'b0000;
                            new_value <= 4'd10;
                            new_rdy <= 1'b1;        
                        end                 
                    4'b0111: begin
                            row <= 4'b0000;
                            new_value <= 4'd11;
                            new_rdy <= 1'b1;        
                        end
                    default: begin
                            row <= 4'b0111;
                            new_value <= 4'd0;
                            new_rdy <= 1'b0;        
                        end
                endcase
            end
            K_CHCK: begin       
                case(list) 
                    4'b1110: begin
                            row <= 4'b0000;
                            new_value <= 4'd12;
                            new_rdy <= 1'b1;        
                        end         
                    4'b1101: begin
                            row <= 4'b0000;
                            new_value <= 4'd13;
                            new_rdy <= 1'b1;        
                        end         
                    4'b1011: begin
                            row <= 4'b0000;
                            new_value <= 4'd14;
                            new_rdy <= 1'b1;        
                        end                 
                    4'b0111: begin
                            row <= 4'b0000;
                            new_value <= 4'd15;
                            new_rdy <= 1'b1;        
                        end
                    default: begin
                            row <= 4'b0000;
                            new_value <= 4'd0;
                            new_rdy <= 1'b0;        
                        end
                endcase
            end
            default: ;
        endcase 
    end

//-------------------------------------
//产生最新键值

always @(posedge clk or negedge rst_n)
    if(!rst_n) value <= 16'h0000;
    else if(new_rdy) value <= {value[11:0],new_value}; 


endmodule