说明一下  我用的是Actel的A3PO30板  晶振是48M的    程序解释得很详细

这个是LCD1602的显示程序   主要是动态机的应用  能够实现动态机保持时间的变化

module yejin(clk,
             reset,
             lcd_rs,
             lcd_rw,
             lcd_e,
             lcd_d);

input clk,reset;
output lcd_rs;
output lcd_rw;
output lcd_e;
output [7:0]lcd_d;

reg lcd_rs,lcd_e;
reg [7:0]lcd_d;

assign lcd_rw=0;

reg [19:0]delay_count;
reg [19:0]num_count;

parameter state1=24'b0000_0000_0000_0000_0000_0001;
parameter state2=24'b0000_0000_0000_0000_0000_0010;
parameter state3=24'b0000_0000_0000_0000_0000_0100;
parameter state4=24'b0000_0000_0000_0000_0000_1000;
parameter state5=24'b0000_0000_0000_0000_0001_0000;
parameter state6=24'b0000_0000_0000_0000_0010_0000;
parameter state7=24'b0000_0000_0000_0000_0100_0000;
parameter state8=24'b0000_0000_0000_0000_1000_0000;
parameter state9=24'b0000_0000_0000_0001_0000_0000;
parameter state10=24'b0000_0000_0000_0010_0000_0000;
parameter state11=24'b0000_0000_0000_0100_0000_0000;
parameter state12=24'b0000_0000_0000_1000_0000_0000;
parameter state13=24'b0000_0000_0001_0000_0000_0000;
parameter state14=24'b0000_0000_0010_0000_0000_0000;
parameter state15=24'b0000_0000_0100_0000_0000_0000;
parameter state16=24'b0000_0000_1000_0000_0000_0000;
parameter state17=24'b0000_0001_0000_0000_0000_0000;
parameter state18=24'b0000_0010_0000_0000_0000_0000;
parameter state19=24'b0000_0100_0000_0000_0000_0000;
parameter state20=24'b0000_1000_0000_0000_0000_0000;
parameter state21=24'b0001_0000_0000_0000_0000_0000;
parameter state22=24'b0010_0000_0000_0000_0000_0000;
parameter state23=24'b0100_0000_0000_0000_0000_0000;


reg [23:0]state;
reg state_change;

always@(posedge clk or negedge reset)
begin
  if(!reset)
    begin
      state_change<=1'b0;
      delay_count<=1'b1;
    end
  else
    if(delay_count==num_count-1)
      begin
        state_change<=1'b1;
        delay_count<=1'b1;
      end
    else
      begin
        state_change<=1'b0;
        delay_count<=delay_count+1'b1;
      end
end

always@(posedge state_change or negedge reset)
begin
  if(!reset)
    begin
      state<=state1;
      num_count<=20'd750000;  //大概15ms
    end
  else
    begin
      case(state)
        state1:
          begin
                 state<=state2;
                 num_count<=20'd4;   //大概80ns
                 lcd_rs<=1'b0;
                 lcd_e<=1'b0;
                 lcd_d<=8'b0011_1000;
          end
        state2:
          begin
                 state<=state3;
                 num_count<=20'd12;  ////大概240ns
                 lcd_e<=1'b1;
          end
        state3:
          begin
                 state<=state4;
                 num_count<=20'd5000;  //大概10us
                 lcd_e<=1'b0;
          end

        state4:
          begin
                 state<=state5;
                 num_count<=20'd4;
                 lcd_d<=8'b0000_1100;
          end
        state5:
          begin
                 state<=state6;
                 num_count<=20'd12;
                 lcd_e<=1'b1;
          end
        state6:
          begin
                 state<=state7;
                 num_count<=20'd5000;
                 lcd_e<=1'b0;
          end
        state7:
          begin
                 state<=state8;
                 num_count<=20'd4;
                 lcd_d<=8'b0000_0110;
          end
        state8:begin
                 state<=state9;
                 num_count<=20'd12;
                 lcd_e<=1'b1;
               end
        state9:begin
                 state<=state10;
                 num_count<=20'd5000;
                 lcd_e<=1'b0;
               end
        state10:begin
                 state<=state11;
                 num_count<=20'd4;
                 lcd_d<=8'b0000_0001;
               end
        state11:begin
                 state<=state12;
                 num_count<=20'd12;
                 lcd_e<=1'b1;
               end
        state12:begin
                 state<=state13;
                 num_count<=20'd5000;
                 lcd_e<=1'b0;
               end
        state13:begin
                  state<=state14;
                  num_count<=20'd2000;
                end
        state14:begin
                  state<=state15;
                  num_count<=20'd4;
                  lcd_rs<=1'b0;
                  lcd_e<=1'b0;
                  lcd_d<=8'b10000000;
                end
        state15:begin
                  state<=state16;
                  num_count<=20'd12;
                  lcd_e<=1'b1;
                end
        state16:begin
                  state<=state17;
                  num_count<=20'd5000;
                  lcd_e<=1'b0;
                end
        state17:begin
                  state<=state18;
                  num_count<=20'd4;
                  lcd_rs<=1'b1;
                  lcd_d<=8'b0100_0001;
                end
        state18:begin
                  state<=state19;
                  num_count<=20'd12;
                  lcd_e<=1'b1;
                end
        state19:begin
                  state<=state20;
                  num_count<=20'd5000;
                  lcd_e<=1'b0;
                end
        state20:begin
                  state<=state21;
                  num_count<=20'd4;
                  lcd_d<=8'b0100_1011;
                end
        state21:begin
                  state<=state22;
                  num_count<=20'd12;
                  lcd_e<=1'b1;
                end
        state22:begin
                  state<=state23;
                  num_count<=20'd5000;
                  lcd_e<=1'b0;
                end
        state23:begin
                  state<=state14;
                  num_count<=20'd800;
                end
        default:begin
                  state<=state1;
                  num_count<=20'd800;
                end
      endcase
    end
end
endmodule