常用testbench语法
- $finish 和 $stop ： $finish任务用于终止仿真并跳出仿真器；$stop任务则用于中止仿真。
- `timescale [time_unit] / [time_precision] ：time_unit指定计时和延时的测量单位，time_precision则是指定仿真器的精度。
- #n ：代表延时n个时间轴单位。
- initial ：initial 块执行一次。inital 块内是顺序执行的。一般来给信号赋初值。
- always ：always表示由事件激发反复执行。
操作步骤
仿真程序仍然用上次的一个分频计数程序：
module traffic(Clk_50M, Rst, Clk30, Clk_1Hz);
input Clk_50M, Rst;
output Clk30,Clk_1Hz;
//------------分频器------------------
reg Clk_1Hz;//分频器 50M分频
reg[31:0] Cnt_1Hz;//计数
always@(posedge Clk_50M or negedge Rst)
begin
if(!Rst)//Rst为0时 进行复位 置初值
begin
Cnt_1Hz <= 1;
Clk_1Hz <= 1;
end
else
begin
if(Cnt_1Hz >= 2)//为了显示波形这里25000000临时改为2
begin
Cnt_1Hz <= 1;//计数器置1
Clk_1Hz <= ~Clk_1Hz;
end
else
Cnt_1Hz <= Cnt_1Hz +1;//计数
end
end
//------------计数器------------------
reg[7:0] Cnt30;//计数器
reg Clk30;
always@(posedge Clk_1Hz or negedge Rst)
begin
if(!Rst)
begin
Cnt30 <= 0;
Clk30 <= 1;
end
else
begin
if(Cnt30 >= 30)
begin
Cnt30 <= 0;//计数到30清零
Clk30 <= ~Clk30;
end
else
Cnt30 <= Cnt30 + 1;
end
end
endmodule
这里的TestBench可以自己编写也可以使用软件自动生产的模版。
首先建立一个波形仿真文件：
然后，Edit——>Insert——>Insert Node or Bus：
选择 Run Functional Simulation：
此时工程文件下会产生simulation文件夹：
这时选择 Processing——>Start——>Start Test Bench Template Writer
simulation文件夹下的modelsim文件夹内会产生一个TestBench模板
traffic.vt文件内容：
// Copyright (C) 1991-2013 Altera Corporation
// Your use of Altera Corporation's design tools, logic functions
// and other software and tools, and its AMPP partner logic
// functions, and any output files from any of the foregoing
// (including device programming or simulation files), and any
// associated documentation or information are expressly subject
// to the terms and conditions of the Altera Program License
// Subscription Agreement, Altera MegaCore Function License
// Agreement, or other applicable license agreement, including,
// without limitation, that your use is for the sole purpose of
// programming logic devices manufactured by Altera and sold by
// Altera or its authorized distributors. Please refer to the
// applicable agreement for further details.
// *****************************************************************************
// This file contains a Verilog test bench template that is freely editable to
// suit user's needs .Comments are provided in each section to help the user
// fill out necessary details.
// *****************************************************************************
// Generated on "05/03/2023 19:08:39"
// Verilog Test Bench template for design : traffic
//
// Simulation tool : ModelSim-Altera (Verilog)
//
`timescale 1 ps/ 1 ps
module traffic_vlg_tst();
// constants
// general purpose registers
reg eachvec;
// test vector input registers
reg Clk_50M;
reg Rst;
// wires
wire Clk30;
wire Clk_1Hz;
// assign statements (if any)
traffic i1 (
// port map - connection between master ports and signals/registers
.Clk30(Clk30),
.Clk_1Hz(Clk_1Hz),
.Clk_50M(Clk_50M),
.Rst(Rst)
);
initial
begin
// code that executes only once
// insert code here --> begin
// --> end
$display("Running testbench");
end
always
// optional sensitivity list
// @(event1 or event2 or .... eventn)
begin
// code executes for every event on sensitivity list
// insert code here --> begin
@eachvec;
// --> end
end
endmodule
这时在工程内新建一个Verilog HDL File，将traffic.vt文件内容复制进去，保存为traffic_vlg_tst.v。
然后在该模版上进行修改：
// Copyright (C) 1991-2013 Altera Corporation
// Your use of Altera Corporation's design tools, logic functions
// and other software and tools, and its AMPP partner logic
// functions, and any output files from any of the foregoing
// (including device programming or simulation files), and any
// associated documentation or information are expressly subject
// to the terms and conditions of the Altera Program License
// Subscription Agreement, Altera MegaCore Function License
// Agreement, or other applicable license agreement, including,
// without limitation, that your use is for the sole purpose of
// programming logic devices manufactured by Altera and sold by
// Altera or its authorized distributors. Please refer to the
// applicable agreement for further details.
// *****************************************************************************
// This file contains a Verilog test bench template that is freely editable to
// suit user's needs .Comments are provided in each section to help the user
// fill out necessary details.
// *****************************************************************************
// Generated on "05/03/2023 15:40:48"
// Verilog Test Bench template for design : traffic
//
// Simulation tool : ModelSim-Altera (Verilog)
//
`timescale 1 ps/ 1 ps
module traffic_vlg_tst();
// constants
// general purpose registers
reg eachvec;
// test vector input registers
reg Clk_50M;
reg Rst;
// wires
wire Clk30;
wire Clk_1Hz;
// assign statements (if any)
traffic i1 (
// port map - connection between master ports and signals/registers
.Clk30(Clk30),
.Clk_1Hz(Clk_1Hz),
.Clk_50M(Clk_50M),
.Rst(Rst)
);
initial
begin
// code that executes only once
// insert code here --> begin
#0
Clk_50M = 0;
Rst = 0;
#100
Rst = 1;
#8000 $stop;
// --> end
$display("Running testbench");
end
always #5 Clk_50M <=~ Clk_50M;
// always
// // optional sensitivity list
// // @(event1 or event2 or .... eventn)
// begin
// // code executes for every event on sensitivity list
// // insert code here --> begin
// always #5 Clk_50M <=~ Clk_50M;
// @eachvec;
// // --> end
// end
endmodule
点击Assignments——>setting——>EDA Tool Settings——>Simulation
输入Test bench name，并在添加Test bench and simulation files中选中traffic_vlg_tst.v：
然后编译及运行
点击Processing——>Start Compilation，进行编译
编译完成后，点击Tools——>Run Simulation Tool——>RTL Simulation
然后可以看到仿真结果：
