状态机问题

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唐顺之

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发表于 2013-8-18 16:12 | 只看该作者回帖奖励

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1.源代码如下不能生成状态转移图
module fsm(

clk,

reset,

A,

K1,

K2,

state
         );

input clk,reset,A;
output K1,K2;
//output[1:0] state;
reg K1,K2;
reg [1:0] state;

parameter  Idle = 2'b00,

Start= 2'b01,

Stop = 2'b10,

Clear= 2'b11;

always @(posedge clk)
begin
if(!reset)
begin
   state<=Idle;
   K2<=0;
   K1<=0;
end
else
begin
   case(state)
   Idle:
   begin
      if(A)
      begin
         state<=Start;
         K1<=0;
      end
      else
      begin
         state<=Idle;
         K2<=0;
         K1<=0;
      end
   end
   Start:
   begin
      if(!A)
      begin
         state<=Stop;
      end
      else
      begin
         state<=Start;
      end
   end
   Stop:
   begin
      if(A)
      begin
         state<=Clear;
         K2<=1;
      end
      else
      begin
         state<=Stop;
         K2<=0;
         K1<=0;
      end
   end
   Clear:
   begin
      if(!A)
      begin
         state<=Idle;
         K2<=0;
         K1<=1;
      end
      else
      begin
         state<=Clear;
         K2<=0;
         K1<=0;
      end
   end
   default:
   begin
      state<=Idle;
      K2<=0;
      K1<=0;
   end
endcase
end
end
endmodule

2.源代码如下能生成状态转移图
module fsm(

clk,

reset,

A,

K1,

K2
         );

input clk,reset,A;
output K1,K2;

reg K1,K2;
reg [1:0] state;

parameter  Idle = 2'b00,

Start= 2'b01,

Stop = 2'b10,

Clear= 2'b11;

always @(posedge clk)
begin
if(!reset)
begin
   state<=Idle;
   K2<=0;
   K1<=0;
end
else
begin
   case(state)
   Idle:
   begin
      if(A)
      begin
         state<=Start;
         K1<=0;
      end
      else
      begin
         state<=Idle;
         K2<=0;
         K1<=0;
      end
   end
   Start:
   begin
      if(!A)
      begin
         state<=Stop;
      end
      else
      begin
         state<=Start;
      end
   end
   Stop:
   begin
      if(A)
      begin
         state<=Clear;
         K2<=1;
      end
      else
      begin
         state<=Stop;
         K2<=0;
         K1<=0;
      end
   end
   Clear:
   begin
      if(!A)
      begin
         state<=Idle;
         K2<=0;
         K1<=1;
      end
      else
      begin
         state<=Clear;
         K2<=0;
         K1<=0;
      end
   end
   default:
   begin
      state<=Idle;
      K2<=0;
      K1<=0;
   end
endcase
end
end
endmodule

请问各位大神这是什么原因