1 //1.常规时钟
2
3 //1) initial:
4
5 parameter clk_period = 10;
6
7 reg clk;
8
9 initial begin
10
11 clk = 1'b0;
12
13 forever
14
15 #(clk_period / 2) clk = ~clk;
16
17 end
18
19
20
21 //2) always:
22
23 parameter clk_period = 10;
24
25 reg clk;
26
27 initial
28
29 clk = 0;
30
31 always #(clk_period / 2) clk = ~clk;
32
33
34
35 //2.占空比可调时钟
36
37 //占空比：High_time / (High_time + Low_time)
38
39 parameter High_time = 5, Low_time = 10;
40
41 reg = clk;
42
43 always
44
45 begin
46
47 clk = 1;
48
49 # High_time;
50
51 clk = 0;
52
53 # Low_time;
54
55 end
56
57
58
59 //3.偏移相位时钟信号
60
61 //相位偏移：360 * pshift_time / (High_time + Low_time)
62
63 parameter High_time = 5, Low_time = 10， pshift_time = 2；
64
65 reg = clk;
66
67 always
68
69 begin
70
71 clk = 1;
72
73 # High_time;
74
75 clk = 0;
76
77 # Low_time;
78
79 end
80
81 assign #(pshift_time) clk_p = clk;
82
83
84
85 //4.固定数目时钟信号
86
87 parameter clk_cnt = 50, clk_period = 2;
88
89 reg clk;
90
91 initial
92
93 begin
94
95 clk = 0;
96
97 repeat(clk_cnt)
98
99 #(clk_period / 2) clk = ~clk;
100
101 end
102
103
104
105 //5.复位信号
106
107 //1)异步复位
108
109 parameter rst_repiod = 100;
110
111 reg rst_n;
112
113 initial
114
115 begin
116
117 rst_n = 0;
118
119 #rst_repiod;
120
121 rst_n = 1;
122
123 end
124
125
126
127 //2)同步复位
128
129 parameter rst_repiod = 100;
130
131 reg rst_n;
132
133 initial begin
134
135 rst_n = 1;
136
137 @(posedge clk)
138
139 rst_n = 0;
140
141 #rst_repiod;
142
143 rst_n = 1;
144
145 end
