本练习的目的是使用计数器。
Part I 用T触发器实现16-bit的计数器
参照图 1所示的4-bit的同步计数器，实现一个16-bit 的计数器。
代码１６－ｂｉｔ ｃｏｕｎｔｅｒ
1 //top-level file
2 module part1(KEY0,SW,HEX3,HEX2,HEX1,HEX0);
3 input KEY0; //时钟脉冲
4 input [1:0]SW; //使能&复位
5 output [6:0]HEX3,HEX2,HEX1,HEX0; //输出显示
6 wire [15:0]q; //16-bit计数输出
7
8 counter_16(SW[1],KEY0,SW[0],q);
9
10 seg7_lut H0(q[3:0],HEX0);
11 seg7_lut H1(q[7:4],HEX1);
12 seg7_lut H2(q[11:8],HEX2);
13 seg7_lut H3(q[15:12],HEX3);
14
15 endmodule
1 //由T触发器构建的16-bit计数器
2 module counter_16(en,clk,clr,Q);
3 input en,clk,clr;
4 wire [15:0]q;
5 output [15:0]Q;
6 t_ff u0(en,clk,clr,q[0]);
7 t_ff u1(en&q[0],clk,clr,q[1]);
8 t_ff u2(en&q[0]&q[1],clk,clr,q[2]);
9 t_ff u3(en&q[0]&q[1]&q[2],clk,clr,q[3]);
10 t_ff u4(en&q[0]&q[1]&q[2]&q[3],clk,clr,q[4]);
11 t_ff u5(en&q[0]&q[1]&q[2]&q[3]&q[4],clk,clr,q[5]);
12 t_ff u6(en&q[0]&q[1]&q[2]&q[3]&q[4]&q[5],clk,clr,q[6]);
13 t_ff u7(en&q[0]&q[1]&q[2]&q[3]&q[4]&q[5]&q[6],clk,clr,q[7]);
14 t_ff u8(en&q[0]&q[1]&q[2]&q[3]&q[4]&q[5]&q[6]&q[7],clk,clr,q[8]);
15 t_ff u9(en&q[0]&q[1]&q[2]&q[3]&q[4]&q[5]&q[6]&q[7]&q[8],
16 clk,clr,q[9]);
17 t_ff u10(en&q[0]&q[1]&q[2]&q[3]&q[4]&q[5]&q[6]&q[7]&q[8]&q[9],
18 clk,clr,q[10]);
19 t_ff u11(en&q[0]&q[1]&q[2]&q[3]&q[4]&q[5]&q[6]&q[7]&q[8]&q[9]&q[10],
20 clk,clr,q[11]);
21 t_ff u12(en&q[0]&q[1]&q[2]&q[3]&q[4]&q[5]&q[6]&q[7]&q[8]&q[9]&q[10]&q[11],
22 clk,clr,q[12]);
23 t_ff u13(en&q[0]&q[1]&q[2]&q[3]&q[4]&q[5]&q[6]&q[7]&q[8]&q[9]&q[10]&q[11]&q[12],
24 clk,clr,q[13]);
25 t_ff u14(en&q[0]&q[1]&q[2]&q[3]&q[4]&q[5]&q[6]&q[7]&q[8]&q[9]&q[10]&q[11]&q[12]&q[13],
26 clk,clr,q[14]);
27 t_ff u15(en&q[0]&q[1]&q[2]&q[3]&q[4]&q[5]&q[6]&q[7]&q[8]&q[9]&q[10]&q[11]&q[12]&q[13]&q[14],
28 clk,clr,q[15]);
29
30 assign Q=q;
31
32 endmodule
1 //T flip flop
2 module t_ff(t,clk,rst_n,q);
3 input t,clk,rst_n;
4 outputreg q;
5
6 always @(posedge clk)
7 begin
8 if(!rst_n)
9 q<=0;
10 else
11 begin
12 if(t==1'b1)
13 q<=~q;
14 else
15 q<=q;
16 end
17 end
18
19 endmodule
图２ Ｆｍａｘ值
图３ 占用的ＬＥ数量
Part ＩＩ 用赋值语句实现１６-ｂｉｔ计数器
代码
1 //counter-16bit
2 module part2(clk,rst_n,q);
3 input clk,rst_n;
4 outputreg [15:0]q;
5
6 always @(posedge clk)
7 begin
8 if(!rst_n)
9 q<=1'b0;
10 else
11 begin
12 if(q==65535)
13 q<=0;
14 else
15 q<=q+1;
16 end
17 end
18
19 endmodule
图４ １６-ｂｉｔ计数器的ＲＴＬ视图
图５ Ｆｍａｘ值
图６ １６-ｂｉｔ计数器占用的ＬＥ
Part ＩＩＩ 用ＬＰＭ实现１６-ｂｉｔ计数器
代码
1 //Top-level file
2 module counter_lpm(en,clk,clr,q);
3 input en,clk,clr;
4 output [15:0]q;
5
6 megcounter counter_16bit(.clock(clk),.cnt_en(en),.sclr(clr),
7 .q(q)
8 );
9 endmodule
1 // synopsys translate_off
2 `timescale 1 ps /1 ps
3 // synopsys translate_on
4 module megcounter (
5 clock,
6 cnt_en,
7 sclr,
8 q);
9
10 input clock;
11 input cnt_en;
12 input sclr;
13 output [15:0] q;
14
15 wire [15:0] sub_wire0;
16 wire [15:0] q = sub_wire0[15:0];
17
18 lpm_counter lpm_counter_component (
19 .sclr (sclr),
20 .clock (clock),
21 .cnt_en (cnt_en),
22 .q (sub_wire0),
23 .aclr (1'b0),
24 .aload (1'b0),
25 .aset (1'b0),
26 .cin (1'b1),
27 .clk_en (1'b1),
28 .cout (),
29 .data ({16{1'b0}}),
30 .eq (),
31 .sload (1'b0),
32 .sset (1'b0),
33 .updown (1'b1));
34 defparam
35 lpm_counter_component.lpm_direction ="UP",
36 lpm_counter_component.lpm_port_updown ="PORT_UNUSED",
37 lpm_counter_component.lpm_type ="LPM_COUNTER",
38 lpm_counter_component.lpm_width =16;
39
40
41 endmodule
图７ 用ＬＰＭ实现１６-ｂｉｔ计数器所占用的ＬＥ
Part ＩＶ 循环显示０-９
在ＨＥＸ０上循环显示０-９，每秒刷新一次。
代码
1 //top-level file
2 module seg_number(
3 output [6:0]HEX0,
4 input CLOCK_50,
5 input [0:0]KEY
6 );
7
8 wire clk_1hz;
9 reg [3:0]cnt;
10
11 div u0(
12 .o_clk(clk_1hz),
13 .i_clk(CLOCK_50),
14 .rst_n(KEY)
15 );
16
17 always @(posedge clk_1hz ornegedge KEY)
18 begin
19 if(!KEY)
20 cnt<=4'b0;
21 else
22 begin
23 if(cnt==4'd9)
24 cnt<=4'b0;
25 else
26 cnt<=cnt+1'b1;
27 end
28 end
29
30 seg7_lut u1(
31 .oseg(HEX0),
32 .idig(cnt[3:0])
33 );
34 endmodule
35
36 //divider
37 module div(
38 outputreg o_clk,
39 input rst_n,
40 input i_clk
41 );
42
43 parameter N=50_000_000;
44 parameter M=24_999_999;
45
46 reg [25:0]cnt;
47
48 always @(posedge i_clk ornegedge rst_n)
49 begin
50 if(!rst_n)
51 cnt<=26'b0;
52 else
53 begin
54 if(cnt==N-1)
55 cnt<=26'b0;
56 else
57 cnt<=cnt+26'b1;
58 end
59 end
60 always @(posedge i_clk ornegedge rst_n)
61 begin
62 if(!rst_n)
63 o_clk<=0;
64 else
65 begin
66 if(cnt<=M)
67 o_clk<=1;
68 else
69 o_clk<=0;
70 end
71 end
72
73 endmodule
74
75 //seg7_lut
76 module seg7_lut (
77 outputreg [6:0] oseg,
78 input [3:0] idig
79 );
80 always @ (idig)
81 begin
82 case (idig)
83 4'h1: oseg = 7'b1111001; // ---t---
84 4'h2: oseg = 7'b0100100; // | |
85 4'h3: oseg = 7'b0110000; // lt rt
86 4'h4: oseg = 7'b0011001; // | |
87 4'h5: oseg = 7'b0010010; // ---m---
88 4'h6: oseg = 7'b0000010; // | |
89 4'h7: oseg = 7'b1111000; // lb rb
90 4'h8: oseg = 7'b0000000; // | |
91 4'h9: oseg = 7'b0011000; // ---b---
92 4'ha: oseg = 7'b0001000;
93 4'hb: oseg = 7'b0000011;
94 4'hc: oseg = 7'b1000110;
95 4'hd: oseg = 7'b0100001;
96 4'he: oseg = 7'b0000110;
97 4'hf: oseg = 7'b0001110;
98 default: oseg =7'b1000000;
99 endcase
100 end
101 endmodule
Part Ｖ 循环显示ＨＥＬＬＯ
在ＨＥＸ７－ＨＥＸ０上循环显示ＨＥＬＬＯ，如图８所示。
图８ ８个７ｓｅｇｍｅｎｔ上循环显示ＨＥＬＬＯ
代码
top-level file
1 //top-level file
2 module hello(HEX7,HEX6,HEX5,HEX4,
3 HEX3,HEX2,HEX1,HEX0,
4 CLOCK_50,KEY);
5 input CLOCK_50;
6 input [0:0]KEY;
7 output [6:0]HEX7,HEX6,HEX5,HEX4,HEX3,HEX2,
8 HEX1,HEX0;
9
10 wire clk_1hz;
11 reg [3:0]cnt;
12
13 div u0(.o_clk(clk_1hz),
14 .rst_n(KEY),
15 .i_clk(CLOCK_50)
16 );
17
18 always @(posedge clk_1hz ornegedge KEY)
19 begin
20 if(!KEY)
21 cnt<=4'b0;
22 else
23 begin
24 if(cnt==4'b0111)
25 cnt<=4'b0;
26 else
27 cnt<=cnt+1'b1;
28 end
29 end
30
31 seg7_h0 h0(.oseg(HEX0),
32 .idig(cnt)
33 );
34 seg7_h1 h1(.oseg(HEX1),
35 .idig(cnt)
36 );
37 seg7_h2 h2(.oseg(HEX2),
38 .idig(cnt)
39 );
40 seg7_h3 h3(.oseg(HEX3),
41 .idig(cnt)
42 );
43 seg7_h4 h4(.oseg(HEX4),
44 .idig(cnt)
45 );
46 seg7_h5 h5(.oseg(HEX5),
47 .idig(cnt)
48 );
49 seg7_h6 h6(.oseg(HEX6),
50 .idig(cnt)
51 );
52 seg7_h7 h7(.oseg(HEX7),
53 .idig(cnt)
54 );
55 endmodule
分频器
1 //divider
2 module div(
3 outputreg o_clk,
4 input rst_n,
5 input i_clk
6 );
7
8 parameter N=50_000_000;
9 parameter M=24_999_999;
10
11 reg [25:0]cnt;
12
13 always @(posedge i_clk ornegedge rst_n)
14 begin
15 if(!rst_n)
16 cnt<=26'b0;
17 else
18 begin
19 if(cnt==N-1)
20 cnt<=26'b0;
21 else
22 cnt<=cnt+26'b1;
23 end
24 end
25 always @(posedge i_clk ornegedge rst_n)
26 begin
27 if(!rst_n)
28 o_clk<=0;
29 else
30 begin
31 if(cnt<=M)
32 o_clk<=1;
33 else
34 o_clk<=0;
35 end
36 end
37
38 endmodule
译码0
1 //seg7_lut
2 module seg7_h0
3 (
4 outputreg [6:0] oseg,
5 input [3:0] idig
6 );
7 always @ (idig)
8 begin
9 case (idig)
10 4'h0: oseg = 7'b1000000; //O
11 //4'h1: oseg = 7'b1111001;
12 //4'h2: oseg = 7'b0100100;
13 //4'h3: oseg = 7'b0110000;
14 4'h4: oseg = 7'b0001001; //H
15 4'h5: oseg = 7'b0000110; //E
16 4'h6: oseg = 7'b1000111; //L
17 4'h7: oseg = 7'b1000111; //L
18
19 default: oseg =7'b1111111;
20 endcase
21 end
22 endmodule
译码1
1 //seg7_lut
2 module seg7_h1
3 (
4 outputreg [6:0] oseg,
5 input [3:0] idig
6 );
7 always @ (idig)
8 begin
9 case (idig)
10 4'h1: oseg = 7'b1000000; //O
11 //4'h4: oseg = 7'b1111001;
12 //4'h2: oseg = 7'b0100100;
13 //4'h3: oseg = 7'b0110000;
14 4'h5: oseg = 7'b0001001; //H
15 4'h6: oseg = 7'b0000110; //E
16 4'h7: oseg = 7'b1000111; //L
17 4'h0: oseg = 7'b1000111; //L
18
19 default: oseg =7'b1111111;
20 endcase
21 end
22 endmodule
共8个译码模块（略6）
解法2
1 module part5(CLOCK_50,HEX7,HEX6,HEX5,HEX4,HEX3,HEX2,HEX1,HEX0);
2 input CLOCK_50;
3 output reg [6:0] HEX7,HEX6,HEX5,HEX4,HEX3,HEX2,HEX1,HEX0;
4
5 parameter blank=7'b1_111_111,
6 H=7'b0_001_001,
7 E=7'b0_000_110,
8 L=7'b1_000_111,
9 O=7'b1_000_000;
10
11 wire clk_1hz;
12 wire [3:0] cnt;
13
14 div u0(CLOCK_50,clk_1hz,1'b1);
15 counter8 u1(clk_1hz,1'b1,cnt);
16
17 always @(cnt)
18 case(cnt)
19 4'd0:begin
20 HEX7=blank;
21 HEX6=blank;
22 HEX5=blank;
23 HEX4=H;
24 HEX3=E;
25 HEX2=L;
26 HEX1=L;
27 HEX0=O;
28 end
29 4'd1:begin
30 HEX0=blank;
31 HEX7=blank;
32 HEX6=blank;
33 HEX5=H;
34 HEX4=E;
35 HEX3=L;
36 HEX2=L;
37 HEX1=O;
38 end
39 4'd2:begin
40 HEX1=blank;
41 HEX0=blank;
42 HEX7=blank;
43 HEX6=H;
44 HEX5=E;
45 HEX4=L;
46 HEX3=L;
47 HEX2=O;
48 end
49 4'd3:begin
50 HEX2=blank;
51 HEX1=blank;
52 HEX0=blank;
53 HEX7=H;
54 HEX6=E;
55 HEX5=L;
56 HEX4=L;
57 HEX3=O;
58 end
59 4'd4:begin
60 HEX3=blank;
61 HEX2=blank;
62 HEX1=blank;
63 HEX0=H;
64 HEX7=E;
65 HEX6=L;
66 HEX5=L;
67 HEX4=O;
68 end
69 4'd5:begin
70 HEX4=blank;
71 HEX3=blank;
72 HEX2=blank;
73 HEX1=H;
74 HEX0=E;
75 HEX7=L;
76 HEX6=L;
77 HEX5=O;
78 end
79 4'd6:begin
80 HEX5=blank;
81 HEX4=blank;
82 HEX3=blank;
83 HEX2=H;
84 HEX1=E;
85 HEX0=L;
86 HEX7=L;
87 HEX6=O;
88 end
89 4'd7:begin
90 HEX6=blank;
91 HEX5=blank;
92 HEX4=blank;
93 HEX3=H;
94 HEX2=E;
95 HEX1=L;
96 HEX0=L;
97 HEX7=O;
98 end
99 endcase
100
101 endmodule
102
其实还可以利用字型码加1的方法。
Conclusion
Ｐａｒｔ１ 有助于理解计数器的具体实现，Ｐａｒｔ４是Ｐａｒｔ５的基础，单个７segment循环显示操作成功，多个
自然不难。：）
Reference
《Using library modules ｉｎ Verilog Designｓ 》
