自动售饮料机的verilog实现

自动售饮料机的verilog实现。

每瓶饮料2.5元，可投入0.5与1.0两种硬币，具有找零功能。

说明：此处只是功能的简单实现，没有过多考虑实际售饮料机功能的完整性，可根据需要在此基础上进行修改，、。

代码：

  1 module drink_seller(rst_n,
  2                             clk,
  3                             buy,
  4                             money,
  5                             drink,
  6                             change
  7                                  );
  8 input rst_n;
  9 input clk;
 10 input buy;
 11 input [1:0] money;
 12 
 13 output drink;
 14 output [1:0] change;
 15 
 16 parameter IDLE = 6'b000001;  //空闲状态
 17 parameter S0 = 6'b000010;     //投币0.5元
 18 parameter S1 = 6'b000100;     //投币0.5元
 19 parameter S2 = 6'b001000;    //投币1.0元
 20 parameter S3 = 6'b010000;    //投币1.5元
 21 parameter S4 = 6'b100000;    //投币2.0元
 22 
 23 reg [5:0] cur_state;
 24 reg [5:0] nxt_state;
 25 
 26 reg drink;
 27 reg [1:0] change;
 28 
 29 //状态寄存，时序逻辑
 30 always@(posedge clk)
 31     if(!rst_n)
 32         cur_state <= 6'b0;
 33     else
 34         cur_state <= nxt_state;
 35 
 36 //状态转换，组合逻辑        
 37 always@(*)
 38     if(!rst_n)
 39         //nxt_state = 6'b0;
 40         nxt_state = IDLE;
 41     else
 42         begin
 43             case(cur_state)
 44             IDLE : if(buy)
 45                         nxt_state = S0;
 46                      else
 47                        nxt_state = IDLE;
 48             S0 : case(money)   //开始投币
 49                          2'b00 :    nxt_state = S0;
 50                          2'b01 :    nxt_state = S1;
 51                          2'b10 :    nxt_state = S2;
 52                          2'b11 :    nxt_state = S3;         
 53                      endcase
 54             S1 : case(money)   //已投币0.5
 55                          2'b00 :    nxt_state = S1;
 56                          2'b01 :    nxt_state = S2;
 57                          2'b10 :    nxt_state = S3;
 58                          2'b11 :    nxt_state = S4;         
 59                      endcase    
 60             S2 : case(money)    //已投币1.0
 61                          2'b00 :    nxt_state = S2;
 62                          2'b01 :    nxt_state = S3;
 63                          2'b10 :    nxt_state = S4;
 64                          2'b11 :    nxt_state = IDLE;         
 65                      endcase
 66             S3 : case(money)    //已投币1.5
 67                          2'b00 :    nxt_state = S3;
 68                          2'b01 :    nxt_state = S4;
 69                          2'b10 :    nxt_state = IDLE;
 70                          2'b11 :    nxt_state = IDLE;         
 71                      endcase
 72             S4 : case(money)    //已投币2.0
 73                          2'b00 :    nxt_state = S4;
 74                          2'b01 :    nxt_state = IDLE;
 75                          2'b10 :    nxt_state = IDLE;
 76                          2'b11 :    nxt_state = IDLE;
 77                      endcase
 78             endcase
 79         end
 80         
 81 //输出控制，组合逻辑        
 82 always@(*)
 83     if(!rst_n)
 84         begin
 85             drink = 1'b0;
 86             change = 2'b00;
 87         end
 88     else begin
 89             case(cur_state)
 90             IDLE,S0,S1: 
 91                         begin 
 92                             drink = 1'b0;
 93                             change = 2'b00;
 94                         end
 95             S2 : case(money)
 96                         2'b11 :    
 97                              begin 
 98                                 drink = 1'b1;
 99                                 change = 2'b00;
100                             end
101                          default : 
102                             begin 
103                                 drink = 1'b0;
104                                 change = 2'b00;
105                             end
106                      endcase
107             S3 : case(money)
108                          2'b10 :    
109                             begin 
110                                 drink = 1'b1;
111                                 change = 2'b00;
112                             end
113                          2'b11 :    
114                             begin 
115                                 drink = 1'b1;
116                                 change = 2'b01;
117                             end
118                         default : 
119                             begin 
120                                 drink = 1'b0;
121                                 change = 2'b00;
122                             end                     
123                      endcase
124             S4 : case(money)
125                          2'b01 :    
126                             begin 
127                                 drink = 1'b1;
128                                 change = 2'b00;
129                             end
130                          2'b10 :    
131                             begin 
132                                 drink = 1'b1;
133                                 change = 2'b01;
134                             end
135                          2'b11 :    
136                             begin 
137                                 drink = 1'b1;
138                                 change = 2'b11;
139                             end
140                         default : 
141                             begin 
142                                 drink = 1'b0;
143                                 change = 2'b00;
144                             end                     
145                      endcase
146             endcase
147         end
148 
149 endmodule

testbench：

 1 module drink_seller_tb;
 2 
 3     // Inputs
 4     reg rst_n;
 5     reg clk;
 6     reg buy;
 7     reg [1:0] money;
 8 
 9     // Outputs
10     wire drink;
11     wire [1:0] change;
12 
13     // Instantiate the Unit Under Test (UUT)
14     drink_seller uut (
15         .rst_n(rst_n), 
16         .clk(clk), 
17         .buy(buy),
18         .money(money), 
19         .drink(drink), 
20         .change(change)
21     );
22     
23     parameter CLK_PERIOD = 10;
24 
25     initial begin
26         rst_n = 0;
27         clk = 1;
28         buy = 0;
29         money = 0;
30 
31         #100;
32         rst_n = 1;
33         # CLK_PERIOD buy = 1;
34         # CLK_PERIOD buy = 0;
35         
36         # 100 buy = 1;
37         # CLK_PERIOD buy = 0;
38         
39         # 100 buy = 1;        
40     
41     end    
42         
43     always #(CLK_PERIOD/2) clk = ~clk;
44     
45     always@(posedge clk)
46     if(!rst_n)
47       money = 2'b00;
48      else
49       money = 2'b01;
50 
51 endmodule