lab05 -- SOS信号之一
本实验要做一个sos信号发生器，如上图所示，由2个模块构成，其中sos_module.v用来产生sos信号，对应莫尔斯电码就是. . . _ _ _ . . .，其中点（短音）用100ms的高电平表示，杠（长音）用300ms的高电平表示，空格用50ms的间隔表示。control_module.v作为控制模块，用来产生一个使能信号sos_en_sig。最后，实验的演示验证部分，由于DE2不带蜂鸣器，暂用LEDG8代替。（当然，用蜂鸣器的效果要明显些）。
代码
sos_module.v
1 /**
2 * File name: sos_module.v
3 *
4 */
5
6 module sos_module
7 (
8 clk, rst_n, pin_out, sos_en
9 );
10
11 input clk;
12 input rst_n;
13 input sos_en;
14 output pin_out;
15
16 parameter T1MS = 16'd50000 - 1;
17
18 reg [15:0] count;
19
20 always @(posedge clk or negedge rst_n)
21 if (!rst_n)
22 count <= 16'd0;
23 else if (iscount && count == T1MS)
24 count <= 16'd0;
25 else if (iscount)
26 count <= count + 1'b1;
27 else if (!iscount)
28 count <= 16'd0;
29
30 reg [9:0] count_ms;
31
32 always @(posedge clk or negedge rst_n)
33 if (!rst_n)
34 count_ms <= 10'd0;
35 else if (iscount && count == T1MS)
36 count_ms <= count_ms + 1'b1;
37 else if (!iscount)
38 count_ms <= 10'd0;
39
40 reg iscount;
41 reg rpin_out;
42 reg [4:0] i;
43
44 always @(posedge clk or negedge rst_n)
45 if (!rst_n)
46 begin
47 iscount <= 1'b0;
48 rpin_out <= 1'b0;
49 i <= 5'd0;
50 end
51 else
52 case(i)
53 5'd0:
54 if (sos_en)
55 i <= 5'd1;
56
57 5'd1, 5'd3, 5'd5, //short
58 5'd13, 5'd15, 5'd17:
59 if (count_ms == 10'd100)
60 begin
61 iscount <= 1'b0;
62 rpin_out <= 1'b0;
63 i <= i + 1'b1;
64 end
65 else
66 begin
67 iscount <= 1'b1;
68 rpin_out <= 1'b1;
69 end
70
71 5'd7, 5'd9, 5'd11: //long
72 if (count_ms == 10'd300)
73 begin
74 iscount <= 1'b0;
75 rpin_out <= 1'b0;
76 i <= i + 1'b1;
77 end
78 else
79 begin
80 iscount <= 1'b1;
81 rpin_out <= 1'b1;
82 end
83
84 5'd2, 5'd4, 5'd6, //interval
85 5'd8, 5'd10, 5'd12,
86 5'd14, 5'd16, 5'd18:
87 if (count_ms == 10'd50)
88 begin
89 iscount <= 1'b0;
90 i <= i + 1'b1;
91 end
92 else
93 iscount <= 1'b1;
94
95 5'd19: //end
96 begin
97 rpin_out <= 1'b0;
98 i <= 5'd0;
99 end
100 endcase
101
102 assign pin_out = rpin_out;
103
104 endmodule
105
106
107
control_module.v
1 /**
2 * File name : control_module.v
3 *
4 */
5
6 module control_module
7 (
8 clk, rst_n, sos_en
9 );
10
11 input clk;
12 input rst_n;
13 output sos_en;
14
15 parameter T3S = 28'd150_000_000 - 1;
16
17 reg isen;
18 reg [27:0] count;
19
20 always @(posedge clk or negedge rst_n)
21 if (!rst_n)
22 begin
23 isen <= 1'b0;
24 count <= 28'd0;
25 end
26 else if (count <= T3S)
27 begin
28 isen <= 1'b1;
29 count <= 26'd0;
30 end
31 else
32 begin
33 isen <= 1'b0;
34 count <= count + 1'b1;
35 end
36
37 assign sos_en = isen;
38
39 endmodule
40
41
sos_generator_module.v
1 /**
2 * File name: sos_generator_module.v
3 *-----------------------------------
4 * pins: KEY0-rst_n, LEDG8-pin_out
5 *-----------------------------------
6 * yf.x
7 * 7-15-2011
8 *
9 */
10
11 module sos_generator_module
12 (
13 CLOCK_50, KEY, LEDG
14 );
15
16 input CLOCK_50;
17 input [0:0] KEY;
18 output [8:8] LEDG;
19
20 wire sos_en;
21
22 control_module U1
23 (
24 .clk (CLOCK_50),
25 .rst_n (KEY),
26 .sos_en (sos_en)
27 );
28
29 wire pin_out_wire;
30
31 sos_module U2
32 (
33 .clk (CLOCK_50),
34 .rst_n (KEY),
35 .sos_en (sos_en),
36 .pin_out (pin_out_wire)
37 );
38
39 assign LEDG = pin_out_wire;
40
41 endmodule
RTL图
小结
控制模块每隔3秒就产生一个使能信号，促使功能模块发出sos信号。至于代码，做到这里，已经能感觉到akuei2的风格，即建模的“仿顺序操作”的思想。