module demo_sound4(
input clock,
output [7:0]key_code,
input k_tr
);



reg  [15:0]tmp;
wire  [15:0]tmpa;
reg   tr;
reg   [15:0]step;
wire  [15:0]step_r;
reg   [7:0]TT;
reg[5:0]st;
reg go_end;

always @(negedge k_tr or posedge clock) begin
if (!k_tr) begin
   step=0;
   st=0;
   tr=0;
end
else
if (step<step_r) begin
  case (st)
  0: st=st+1;
  1: begin tr=0; st=st+1;end
  2: begin tr=1;st=st+1;end
  3: if(go_end) st=st+1;
  4: begin st=0;step=step+1;end
  endcase
end
end

///////////////////////////////////////////
wire  [7:0]key_code1=(
(TT[3:0]==1)?8'h2b:(//1
(TT[3:0]==2)?8'h34:(//2
(TT[3:0]==3)?8'h33:(//3
(TT[3:0]==4)?8'h3b:(//4
(TT[3:0]==5)?8'h42:(//5
(TT[3:0]==6)?8'h4b:(//6
(TT[3:0]==7)?8'h4c:(//7
(TT[3:0]==10)?8'h52:(//1
(TT[3:0]==15)?8'hf0:8'hf0//OFF
))))))))
);

assign key_code=(tmp<(tmpa-1))?key_code1:8'hf0;

assign tmpa[15:0]=(
(TT[7:4]==15)?16'h10:(
(TT[7:4]==8)? 16'h20:(
(TT[7:4]==9)? 16'h30:(
(TT[7:4]==1)? 16'h40:(
(TT[7:4]==3)? 16'h60:(
(TT[7:4]==2)? 16'h80:(
(TT[7:4]==4)? 16'h100:(
(TT[7:4]==5)? 16'hc0:0

)))))))
);


always @(negedge tr or posedge clock)begin
if(!tr) begin tmp=0;go_end=0 ;end
 else if (tmp>tmpa)go_end=1; 
 else tmp=tmp+1;
end


always @(step) begin
case (step)
0:TT=8'h11;
1:TT=8'h91;
2:TT=8'hf1;
3:TT=8'h31;
4:TT=8'h84;
5:TT=8'h15;
6:TT=8'h15;
7:TT=8'h31;
8:TT=8'h83;
9:TT=8'h34;
10:TT=8'h84;
11:TT=8'h35;
12:TT=8'h85;
13:TT=8'h31;

14:TT=8'h81;

15:TT=8'h11;
16:TT=8'h11;

17:TT=8'h31;
18:TT=8'h81;
19:TT=8'h11;
20:TT=8'h11;
21:TT=8'h11;
22:TT=8'h31;

23:TT=8'h1f;
24:TT=8'h1f;
25:TT=8'h81;

26:TT=8'h81;
27:TT=8'h81;
28:TT=8'h81;
29:TT=8'h81;

30:TT=8'h35;
31:TT=8'h85;

32:TT=8'h85;
33:TT=8'h85;
34:TT=8'h85;
35:TT=8'h85;

36:TT=8'h31;
37:TT=8'h81;
38:TT=8'h31;

39:TT=8'h84;
40:TT=8'h15;
41:TT=8'h15;
42:TT=8'h21;
43:TT=8'h1f;
endcase
end

assign step_r=43;

endmodule