2.txt

交通灯状态机的实现

`timescale 1ns / 1ps
////////////////////////////////////////////////////////////////////////////////
// Company: 
// Engineer:
//
// Create Date:    11:32:59 11/02/06
// Design Name:    
// Module Name:    trafficLight2
// Project Name:   
// Target Device:  
// Tool versions:  
// Description:
//
// Dependencies:
// 
// Revision:
// Revision 0.01 - File Created
// Additional Comments:
// 
////////////////////////////////////////////////////////////////////////////////
module trafficLight2(clk, snCar, ewCar,snRed, snYellow, snGreen,ewRed, ewYellow, ewGreen);
 input clk,snCar,ewCar;
 output snRed, snYellow, snGreen,ewRed, ewYellow, ewGreen;
 reg[5:0] state;
 reg  snRed,snYellow,snGreen,ewRed, ewYellow, ewGreen;
 reg[7:0] count;

 //设定count的初始值
 initial begin
 				count = 8'b0;
			end	 

 //设定状态值
 parameter ewgreen =6'b000001, 
			  ewwait	 =6'b000010,
			  ewyellow=6'b000100,
			  sngreen =6'b001000,
			  snwait	 =6'b010000,
			  snyellow=6'b100000;

 always @(posedge clk)				  	
 case(state)	
	 ewgreen: begin
	  					ewGreen <= 1;
						snRed   <= 1;
						snYellow<= 0;
						snGreen <= 0;
						ewRed   <= 0;
						ewYellow<= 0;
	  					 if(count <8'b11000100)
							begin
								count <= count+1;
							   if (count==8'b11000100)
								 	begin
								   	state <= ewwait;
										count <= 0;
								  	end
							end
				 end
	 ewwait: begin
							if (!snCar) 
								begin
	  								ewGreen <= 1;
									snRed   <= 1;
									snYellow<= 0;
									snGreen <= 0;
									ewRed   <= 0;
									ewYellow<= 0;
								end 
							else state <= ewyellow ;
							
				 end
	 ewyellow: begin 
	 						ewYellow <= 1;
							snRed    <= 1;
			  				snYellow <= 0;
							snGreen  <= 0;
							ewRed    <= 0;
							ewGreen  <= 0;
							if(count <8'b00000100)
								begin
									count <= count+1;
							   	if (count==8'b00000100)
								   	begin 
											state <= sngreen;
											count <= 0;
										end
								end
				 end
	 sngreen: begin
	  						snGreen <= 1;
							ewRed   <= 1;
			  				snRed   <= 0;
							snYellow<= 0;
							ewYellow<= 0;
							ewGreen <= 0;
	  					 	if(count <8'b11000100)
								begin
									count <= count+1;
							   	if (count==8'b11000100)
								   	begin 
											state <= snwait;
											count <= 0;
										end
								end
				  end
	 snwait:begin
							if (!ewCar) 
								begin
									snGreen <= 1;
									ewRed   <= 1;
									snRed   <= 0;
									snYellow<= 0;
									ewYellow<= 0;
									ewGreen <= 0;
								end 
							else state <= snyellow ;
				end
	 snyellow: begin 
	 					snYellow <= 1;
						ewRed <= 1;
						snRed<=0;
						snGreen<=0;
						ewYellow<=0;
						ewGreen<=0;
						if(count <8'b00000100)
							begin
								count <= count+1;
							  	if (count==8'b00000100)
									begin
								  		state <= ewgreen;
										count <= 0;
									end
							end
				  end
	default: state <= ewyellow;
	endcase		  	
endmodule