一. 状态机理论基础

状态机基本概念：

状态机类型：

一、二、三段式状态机各自的优缺点：

状态机质量指标

二.Verilog实现状态机例子

2.1FSM实现实现11010110序列输出

状态机设计

module FSM_gener(
	input					clk,
	input					rst_n,
	
	output reg				data_current
);
	//变量分配定义
	reg	[3:0] state_current;
	reg	[3:0] state_next;
	reg 	  data_next;


	localparam       			//使用格雷码，减少数据翻转，减小误码率和功耗
		IDEL  = 4'b0000,
		ONE   = 4'b0001,
		TWO   = 4'b0011,
		THREE = 4'b0010,
		FOUR  = 4'b0110,
		FIVE  = 4'b0111,
		SIX   = 4'b0101,
		SEVEN = 4'b0100,
		EIGHT  = 4'b1100;


	//第一段状态机,时序逻辑状态更新
	always@( posedge clk or negedge rst_n ) begin
		if( !rst_n )
			state_current <= IDEL;
		else
			state_current <= state_next;
	end
	
	//第二段状态机，组合逻辑状态判断跳转
	always@( * ) begin
		case( state_current )
			IDEL:begin
					state_next <= ONE;	
					data_next <= 1'b0;
				 end
			ONE:begin
					state_next <= TWO;
					data_next <= 1'b1;
				end
			TWO: begin
					state_next <= THREE;
					data_next <= 1'b1;
				 end
			THREE:begin
					state_next <= FOUR;
					data_next <= 1'b0;
				  end
			FOUR:begin
					state_next <= FIVE;
					data_next <= 1'b1;
				 end
			FIVE:begin
					state_next <= SIX;
					data_next <= 1'b0;
				 end
			SIX: begin
					state_next <= SEVEN;
					data_next <= 1'b1;
				 end
			SEVEN:begin
					state_next <= EIGHT;
					data_next <= 1'b1;
				  end
			EIGHT:begin
					state_next <= IDEL;
					data_next <= 1'b0;
				  end
			default:begin
						state_next <= IDEL;
						data_next <= 1'b0;
				    end
		endcase
	end
	
	//第三段状态机，时序逻辑数据输出
	always@( posedge clk or negedge rst_n ) begin
		if( !rst_n )
			data_current <= 1'b0;
		else
			data_current <= data_next;
	end

endmodule

仿真验证

`timescale 1ns/1ns
`define clock_period 20

module FSM_gener_tb();

	reg					clk;
	reg					rst_n;
	wire				data_current;

	FSM_gener FSM_gener0
	(
		.clk(clk),
		.rst_n(rst_n),
	    
		.data_current(data_current)
	);
	
	initial begin clk = 1'b1; end
	always#( `clock_period )    clk = ~clk;
	
	initial begin
		rst_n = 0;
		#( `clock_period*10  );
		rst_n = 1;		
		#( `clock_period*10 + 1'b1 );
		#( `clock_period*50 );
		$stop;
	end

endmodule

仿真结果如下所示，状态机循环输出11010110满足设计要求

2.2 连续字符串"aebf"检测

。。。待补充