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1.首先创建一个文件夹，名为 verilator-demo

mkdir verilator-demo

2.接着设计一个电路，名为 ledmodule.v

module ledmodule(
	output reg led,
	input clk,
	input rst
);

reg [2:0] counter = 3'd0;

always @(posedge clk) begin
	counter <= (counter + 1'd1);
	if(counter >= 3'd2) begin
		led <= 1'd1;
	end else begin
		led <= 1'd0;
	end
	if(rst) begin
		counter <= 3'd0;
		led <= 1'd0;
	end
end

endmodule

3.然后编写测试床，这是 cpp 文件，如下：

#include <stdlib.h>
#include <iostream>
#include <verilated.h>
#include <verilated_vcd_c.h>
#include "obj_dir/Vledmodule.h"

#define MAX_TIME 60
vluint64_t sim_time = 0;

int main(int argc, char **argv, char **env) {
	Vledmodule *dut = new Vledmodule;
	Verilated::traceEverOn(true);
	VerilatedVcdC *m_trace = new VerilatedVcdC;
	dut->trace(m_trace, 5);
	m_trace->open("waveform.vcd");

	while(sim_time < MAX_TIME) {
		dut->clk ^= 1;
		dut->rst = 0;
		dut->eval();
		m_trace->dump(sim_time);
		sim_time++;
	}

	m_trace->close();
	delete dut;
	exit(EXIT_SUCCESS);
}

4接着运行如下命令，生成可执行文件，运行可执行文件产生波形

verilator --cc ledmodule.v 
verilator -Wall --trace --exe --build -cc ledmodule.cpp ledmodule.v
./obj_dir/Vledmodule

5.使用 gtkwave 打开波形

gtkwave waveform.vcd

6.最后得到的波形如下图