beep的控制程序

　　参照艾米电子的程序进行改写的

//date : 2014,5,4 

module for_beep (
                              clock ,
                              reset ,
                              out_beep
                              );
input  clock ,reset ;
output  reg out_beep ; 

reg [:]    state ;
reg [:]     clk1 ;
reg [:]   cnt0 ;
reg [:]   delay_cnt1;                      

parameter   du  =   ,
                    re  =   ,
                    mi =   ,
                    fa =    ,
                    so =   ,
                    la  =   ,
                    xi  =   ,
                    do1 =   ; 

always @ (posedge clock  or negedge reset )
        begin
                if (!reset )
                        begin
                                clk1              <=    'd0 ;
                                state            <=    'd0 ;
                                cnt0             <=  'd0 ;
                                delay_cnt1  <=  'd0 ;
                                out_beep     <=   'd0 ;
                        end
                else  if(clk1 == 'd8)
                        begin
                                case (state)
                                        'd0    :    begin
                                                                delay_cnt1  <= delay_cnt1 + 'd1;
                                                                if(delay_cnt1 == 'h1ff_ffff)
                                                                                state          <=  'd1 ;

                                                                if(cnt0 != du)
                                                                            cnt0 <= cnt0 + 'd1 ;
                                                                else
                                                                        begin
                                                                            cnt0 <= 'd0 ;
                                                                            out_beep <= ~out_beep ;
                                                                        end
                                                        end
                                        'd1    :    begin
                                                                delay_cnt1  <= delay_cnt1 + 'd1;
                                                                if(delay_cnt1 == 'h1ff_ffff)
                                                                                state          <=  'd2 ;

                                                                if(cnt0 != re)
                                                                            cnt0 <= cnt0 + 'd1 ;
                                                                else
                                                                        begin
                                                                            cnt0 <= 'd0 ;
                                                                            out_beep <= ~out_beep ;
                                                                        end
                                                        end
                                        'd2    :    begin
                                                                delay_cnt1  <= delay_cnt1 + 'd1;
                                                                if(delay_cnt1 == 'h1ff_ffff)
                                                                                state          <=  'd3 ;

                                                                if(cnt0 != mi)
                                                                            cnt0 <= cnt0 + 'd1 ;
                                                                else
                                                                        begin
                                                                            cnt0 <= 'd0 ;
                                                                            out_beep <= ~out_beep ;
                                                                        end
                                                        end
                                        'd3    :    begin
                                                                delay_cnt1  <= delay_cnt1 + 'd1;
                                                                if(delay_cnt1 == 'h1ff_ffff)
                                                                                state          <=  'd4 ;

                                                                if(cnt0 != fa)
                                                                            cnt0 <= cnt0 + 'd1 ;
                                                                else
                                                                        begin
                                                                            cnt0 <= 'd0 ;
                                                                            out_beep <= ~out_beep ;
                                                                        end
                                                        end
                                        'd4    :    begin
                                                                delay_cnt1  <= delay_cnt1 + 'd1;
                                                                if(delay_cnt1 == 'h1ff_ffff)
                                                                                state          <=  'd5 ;

                                                                if(cnt0 != so)
                                                                            cnt0 <= cnt0 + 'd1 ;
                                                                else
                                                                        begin
                                                                            cnt0 <= 'd0 ;
                                                                            out_beep <= ~out_beep ;
                                                                        end
                                                        end
                                        'd5    :    begin
                                                                delay_cnt1  <= delay_cnt1 + 'd1;
                                                                if(delay_cnt1 == 'h1ff_ffff)
                                                                                state          <=  'd6 ;

                                                                if(cnt0 != la)
                                                                            cnt0 <= cnt0 + 'd1 ;
                                                                else
                                                                        begin
                                                                            cnt0 <= 'd0 ;
                                                                            out_beep <= ~out_beep ;
                                                                        end
                                                        end
                                        'd6    :    begin
                                                                delay_cnt1  <= delay_cnt1 + 'd1;
                                                                if(delay_cnt1 == 'h1ff_ffff)
                                                                                state          <=  'd7 ;

                                                                if(cnt0 != xi)
                                                                            cnt0 <= cnt0 + 'd1 ;
                                                                else
                                                                        begin
                                                                            cnt0 <= 'd0 ;
                                                                            out_beep <= ~out_beep ;
                                                                        end
                                                        end
                                        'd7    :    begin
                                                                delay_cnt1  <= delay_cnt1 + 'd1;
                                                                if(delay_cnt1 == 'h1ff_ffff)
                                                                                state          <=  'd0 ;

                                                                if(cnt0 != do1)
                                                                            cnt0 <= cnt0 + 'd1 ;
                                                                else
                                                                        begin
                                                                            cnt0 <= 'd0 ;
                                                                            out_beep <= ~out_beep ;
                                                                        end
                                                        end 

                                endcase
                        end
                 else  if(clk1 < 'd9 )  clk1 <= clk1 + 4'd1 ;
                 else                           clk1 <= 'd0  ;
        end 

endmodule