module passed_lock(
				clk,
				resetb,
				
				cmd,
				
				alarmed,
				passed,
				password,
				main_state,
				try_count
);
input			clk;			//輸入時鐘信號
input			resetb;		//輸入復位信號
input 	[4:0]	cmd;		//輸入命令信號0
output			alarmed;		//輸出警報信號led
output			passed;		//輸出通過信號led
output  [2:0]   main_state;//lcd
output  [1:0]   try_count;
output  [15:0]  password;
wire			clk;
wire			resetb;
wire	[4:0]	cmd;
reg				alarmed;
reg				passed;
//輸入與輸出的聲明部分，其中，clk為輸入的時鐘信號，resetb為密碼舒服的輸入信號，cmd為輸入命令，需注意的時，cmd并不是總在表示密碼，也表示密碼的間隔，如當輸入4位密碼后需要一個確認“enter”信號，當密碼輸入錯誤時，需要取消“cancel”信號，這些信號之間在設計中通過有限狀態(tài)轉(zhuǎn)換機實現(xiàn)。

parameter		PASSWORD=16'd1234;//盛放密碼的參數(shù)
reg		[15:0]	password;//輸入數(shù)值盛放寄存器

//輸入的數(shù)字編碼 0~9，enter，cancel
reg			    one=5'b10001,
				two=5'b10010,
				three=5'b10011,
				four=5'b10100,
				five=5'b10101,
				six=5'b10110,
				seven=5'b10111,
				eight=5'b11000,
				nine=5'b11001,
				zero=5'b10000,
				
				enter=5'b11010,
				cancel=5'b11011;
reg			cmd_t;//檢驗是否有按鍵按下

reg			[2:0]	main_state;//主狀態(tài)
reg			[2:0]	next_state;//下一個狀態(tài)


//主有限狀態(tài)轉(zhuǎn)換機的三個狀態(tài)：waits、pass、alarm
parameter		    waits=3'b001,
					pass=3'b010,
					alarm=3'b100;

reg		[2:0]	sub_state;
reg		[2:0]	next_sub_state;

 //主有限狀態(tài)轉(zhuǎn)換機的三個狀態(tài)：first、second、third、fourth、finish。
parameter		    first=3'b000,
					second=3'b001,
					third=3'b010,
					fourth=3'b011,
					finish=3'b100;
//通過計時寄存器
reg		[7:0]	pass_count;
//警報計時寄存器
reg		[10:0]	alarm_count;
//嘗試次數(shù)寄存器
reg		[1:0]	try_count;

//輸入狀態(tài)寄存器：error和correct
reg			error;
reg			correct;
//以上為中間狀態(tài)的一些寄存器和一些所用到的參數(shù)
//主機狀態(tài)機部分

always@(main_state or correct or error)
begin
	case(main_state)
		waits:
			if(correct==1) //由waits轉(zhuǎn)換到pass的條件
				next_state=pass;
			else if(error==1&&try_count==2)
				next_state=alarm; //由waits轉(zhuǎn)換到alarm的條件
			else
				next_state=waits;
		pass:
			if(pass_count[7]==1)//由pass轉(zhuǎn)換到waits的條件
				next_state=waits;
			else
				next_state=pass;
		alarm:
			if(alarm_count[10]==1)// 由alarm轉(zhuǎn)換到waits的條件
				next_state=waits;
			else
				next_state=alarm;
		default://默認狀態(tài)：waits
			next_state=waits;
		endcase
	end


//狀態(tài)轉(zhuǎn)換
always@(posedge clk or negedge resetb)
begin
	if(!resetb)
		main_state<=waits;
	else
		main_state<=next_state;
end

//輸出控制部分
always@(posedge clk or negedge resetb)
begin
	if(!resetb)//復位時，開鎖輸出與警報輸出都為零
		begin
			passed<=0;
			alarmed<=0;
		end
	else if(main_state==pass)//當主機狀態(tài)為pass時，開鎖
		begin
			passed<=1;
			alarmed<=0;
		end
	else if(main_state==alarm)//當主機狀態(tài)為alarm時，警報
		begin
			passed<=0;
			alarmed<=1;
		end
	else//其它狀態(tài)復位
		begin
			passed<=0;
			alarmed<=0;
		end
end

//alarm一段時間后，自動進入waits狀態(tài)
//alarm定時器
always@(posedge clk or negedge resetb)
begin
	if(!resetb)
		alarm_count<=0;
	else if(main_state==alarm)//alarm狀態(tài)計時器alarm定時器加1
		alarm_count<=alarm_count+1;
	else
		alarm_count<=0;
end

//鎖pass以后計數(shù)開始，當規(guī)定的時間到達后自動上鎖，并進入waits狀態(tài)
//pass定時器
always@(posedge clk or negedge resetb)
	begin
		if(!resetb)
			pass_count<=0;
		else if(main_state==pass) //pass狀態(tài)計時器pass定時器加1
			pass_count<=pass_count+1;
		else
			pass_count<=0;
	end
	
//從狀態(tài)機，用于輸入4位密碼


always@(posedge clk or negedge resetb)
begin 
	if(!resetb)
		cmd_t<=0;
	else 
		cmd_t<=-cmd[4];
end

always@(posedge clk or negedge resetb)
begin
	if(!resetb)
		sub_state<=first;
	else
		sub_state<=next_sub_state;
end

always@(cmd or cmd_t or sub_state)
//always@(cmd or sub_state)
begin
	if(cmd_t==0&&cmd[4]==1)
		case(cmd)
			cancel://密碼輸入錯誤時，重復上一個狀態(tài)
			begin
				if(sub_state==first)// 第1個密碼輸入錯誤
					next_sub_state=first;
				else
					case(sub_state)
					second: // 第2個密碼輸入錯誤
						next_sub_state=first;
					third: // 第3個密碼輸入錯誤
						next_sub_state=second;
					fourth: // 第4個密碼輸入錯誤
						next_sub_state=third;
					finish:
						next_sub_state=fourth;
					endcase
			end
			enter://4個密碼輸完時，進行確認
				next_sub_state=first;
			//以下4個命令位無效的命令，狀態(tài)保持不變
			5'b11100:
				next_sub_state=next_sub_state;
			5'b11101:
				next_sub_state=next_sub_state;
			5'b11110:
				next_sub_state=next_sub_state;
			5'b11111:
				next_sub_state=next_sub_state;
				
			//default為輸入了某位密碼，輸入完自動將狀態(tài)轉(zhuǎn)入下一位
			default:
				case(sub_state)
				first:
					next_sub_state=second;
				second:
					next_sub_state=third;
				third:
					next_sub_state=fourth;
				fourth:
					next_sub_state=finish;
//當輸入完4位密碼以后狀態(tài)保持不變，等待輸入enter命
//令
				finish:
					next_sub_state=finish;	
				endcase
			endcase
		else
			next_sub_state=sub_state;
end

//比較密碼，產(chǎn)生正確或者錯誤信息
always@(posedge clk or negedge resetb)
begin
	if(!resetb)
		begin
			correct<=0;
			error<=0;
		end
	else if(cmd_t ==0&&cmd==enter)
		if(password==PASSWORD)//密碼正確時
			begin
				correct<=1;
				error<=0;
			end
		else//密碼錯誤時
			begin
				error<=1;
				correct<=0;
			end
		else
			begin
				correct<=0;
				error<=0;
			end
end

//記錄密碼
always@(posedge clk or negedge resetb)
begin
	if(!resetb)
		password<=0;
	else if(cmd_t==0&&cmd[4]==1)
		case(sub_state)
		first:
			password[15:12]<=cmd[3:0];
		second:
			password[11:8]<=cmd[3:0];
		third:
			password[7:4]<=cmd[3:0];
		fourth:
			password[3:0]<=cmd[3:0];
		default:
			password<=password;
		endcase
	else
		password<=password;
end

//記錄錯誤次數(shù)
always@(posedge clk or negedge resetb)
begin
if(!resetb)
		try_count<=0;
	else if(error==1)
		try_count<=try_count+1;
	else if(main_state==pass||main_state==alarm)
		try_count<=0;
	end
endmodule