新建 文本文档.txt

交通灯状态机的实现

module trafficLight(clk_system,reset,snCar, ewCar,
						  			snRed, snYellow, snGreen,
						  			ewRed, ewYellow, ewGreen);

		input	clk_system;
		input	reset;
		input	snCar;
		input	ewCar;
		output	snRed, snYellow, snGreen;
		output	ewRed, ewYellow, ewGreen;
		

		reg	snRed, snYellow, snGreen;
		reg	ewRed, ewYellow, ewGreen;
		reg[3:0]	state;
		reg[7:0]	counter;
		reg	enable;
	  
		
		initial
			begin
					snRed <= 0;
					snYellow <= 0;
					snGreen <= 0;
					ewRed <= 0;
					ewYellow <= 0;
					ewGreen <= 0;
					
					state <= 4'b0001;
					
					counter = 0;
					enable = 0;
					
			end					
		
		always@(posedge clk_system)
			if(reset)
				begin
					snRed <= 0;
					snYellow <= 0;
					snGreen <= 0;
					ewRed <= 0;
					ewYellow <= 0;
					ewGreen <= 0;
					
					state <= 4'b0001;
										
          counter <= 0;
          enable <= 0;
									
				end
			
			else
				case({snCar,ewCar})
					2'b01 : 
                  begin
                    ewGreen <= 1;
                    ewYellow <= 0;
                    ewRed <= 0;
                                
                    snGreen <= 0;
                    snYellow <= 0;
                    snRed <= 1;
                    
                    
                   	state <= 4'b0001;
										
					          counter <= 0;
					          enable <= 0;
					          
									
                  end
									
					2'b10 : 
                  begin
                    ewGreen <= 0;
                    ewYellow <= 0;
                    ewRed <= 1;
                                
                    snGreen <= 1;
                    snYellow <= 0;
                    snRed <= 0;
                    
                   	state <= 4'b0001;
										
					          counter <= 0;
					          enable <= 0;
					          	
                                        
									end
				  
          2'b00 : 
				          begin
				            state <= 4'b0001;
										
					          counter <= 0;
					          enable <= 0;
					        end
					
			2'b11 :
							begin
    		        	
    		        	case(state)
    		          4'b0001:begin
                          
                            if(counter >=50 )  
                              begin
                                state <= 4'b0010;
                                counter <= 0;
                                enable <= 0;
                              end    
                            
                            else  if(enable == 0)
      		                    begin
    		                        ewGreen   <= 1;
                                ewYellow  <= 0;
                                ewRed     <= 0;
                                    
                                snGreen   <= 0;
                                snYellow  <= 0;
                                snRed     <= 1;
                                                                                  
                                enable  <= 1;                              
                                counter <= counter + 1; 
                              end
                           
                            else  counter <= counter + 1;     
                           
                          end
                                
                                
    		          4'b0010:begin
                          
                            if(counter >=20 )  
                              begin
                                state   <= 4'b0100;
                                counter <= 0;
                                enable  <= 0;
                              end    
                            
                            else  if(enable == 0)
      		                    begin
    		                        ewGreen   <= 0;
                                ewYellow  <= 1;
                                ewRed     <= 0;
                                    
                                snGreen   <= 0;
                                snYellow  <= 0;
                                snRed     <= 1;
                                                                                  
                                enable  <= 1;                              
                                counter <= counter + 1; 
                              end
                           
                            else  counter <= counter + 1;     
                           
                          end
                                
                                
    		          4'b0100:begin
                          
                            if(counter >=50 )  
                              begin
                                state   <= 4'b1000;
                                counter <= 0;
                                enable  <= 0;
                              end    
                            
                            else  if(enable == 0)
      		                    begin
    		                        ewGreen   <= 0;
                                ewYellow  <= 0;
                                ewRed     <= 1;
                                    
                                snGreen   <= 1;
                                snYellow  <= 0;
                                snRed     <= 0;
                                                                                  
                                enable  <= 1;                              
                                counter <= counter + 1; 
                              end
                           
                            else  counter <= counter + 1;     
                           
                          end
                                
                                    
    		          4'b1000:begin
                          
                            if(counter >=20 )  
                              begin
                                state   <= 4'b0001;
                                counter <= 0;
                                enable  <= 0;
                              end    
                            
                            else  if(enable == 0)
      		                    begin
    		                        ewGreen   <= 0;
                                ewYellow  <= 0;
                                ewRed     <= 1;
                                    
                                snGreen   <= 0;
                                snYellow  <= 1;
                                snRed     <= 0;
                                                                                  
                                enable  <= 1;                              
                                counter <= counter + 1; 
                              end
                           
                            else  counter <= counter + 1;     
                           
                          end
                                
                                                                                        
    		        endcase
						            
				end
				
				endcase
    			
	
		
		

endmodule