FPGA矩阵键盘的扫描方法

module keyscan(kbrow,seg7_out,scan,clk,start,kbcol);
output [3:0]kbrow;                      //列扫描信号
output [6:0] seg7_out;
output [7:0] scan;
input clk,start;
input [3:0] kbcol;
reg [3:0] kbrow;
reg [6:0] seg7_out;
reg [7:0] scan;
reg [1:0] count;
reg [1:0] sta;
reg [6:0] seg7;
reg [4:0] dat;
regfn;      //按键标志位，判断是否有键被按下

initialscan<='b10000000;              //只使用一个数码管显示

always@(posedgeclk)                  //循环扫描计数器
begin
if(start==0)
  begin seg7<='b0000000;end
else
  begin
   count<=count+1;
   case(count)                      //循环列扫描
    2'b00: beginkbrow<='b0001;sta<='b00;end
    2'b01: beginkbrow<='b0010;sta<='b01;end
    2'b10: beginkbrow<='b0100;sta<='b10;end
    2'b11: beginkbrow<='b1000;sta<='b11;end
   endcase
   case(sta)                       //行扫描译码
    2'b00:begin
          case(kbcol)
          4'b0001: beginseg7<='b1111001;dat<='b00011;end
          4'b0010: beginseg7<='b1101101;dat<='b00010;end
          4'b0100: beginseg7<='b0110000;dat<='b00001;end
          4'b1000: beginseg7<='b1111110;dat<='b00000;end
          default: beginseg7<='b0000000;dat<='b11111;end
          endcase
          end
   2'b01:begin
         case(kbcol)
         4'b0001: beginseg7<='b1110000;dat<='b00111;end
         4'b0010: beginseg7<='b1011111;dat<='b00110;end
         4'b0100: beginseg7<='b1011011;dat<='b00101;end
         4'b1000: beginseg7<='b0110011;dat<='b00100;end
         default: beginseg7<='b0000000;dat<='b11111;end
         endcase
         end
   2'b10:begin
         case(kbcol)
         4'b0001: beginseg7<='b0011111;dat<='b01011;end
         4'b0010: beginseg7<='b1110111;dat<='b01010;end
         4'b0100: beginseg7<='b1111011;dat<='b01001;end
         4'b1000: beginseg7<='b1111111;dat<='b01000;end
         default: beginseg7<='b0000000;dat<='b11111;end
         endcase
         end
   2'b11:begin
         case(kbcol)
         4'b0001: beginseg7<='b1000111;dat<='b01111;end
         4'b0010: beginseg7<='b1001111;dat<='b01110;end
         4'b0100: beginseg7<='b0111101;dat<='b01101;end
         4'b1000: beginseg7<='b1001110;dat<='b01100;end
         default: beginseg7<='b0000000;dat<='b11111;end
         endcase
         end
    default:seg7<='b0000000;
   endcase                
  end
end
always
  beginfn<=~(dat[0]&dat[1]&dat[2]&dat[3]&dat[4]);end//产生按键标志位，用于存储按键信息
always@(posedgefn)     //按键信息存储
  begin seg7_out<=seg7;end

endmodule