www.pudn.com > traffic_control2.rar > traffic_control.vhd, change:2013-03-31,size:1276b

LIBRARY IEEE; 
USE IEEE.STD_LOGIC_1164.ALL; 
ENTITY traffic_control IS 
    PORT ( 
			clk			:IN STD_LOGIC; 
			c1,c2,c3	:OUT STD_LOGIC; 
			w1,w2,w3	:IN STD_LOGIC; 
			r1,r2		:OUT STD_LOGIC; 
			y1,y2		:OUT STD_LOGIC; 
			g1,g2		:OUT STD_LOGIC; 
			reset		:IN STD_LOGIC); 
	END traffic_control; 
 
	ARCHITECTURE a OF traffic_control IS 
	  TYPE STATE_SPACE IS (S0,S1,S2,S3); 
	  SIGNAL state:STATE_SPACE; 
	BEGIN 
	  PROCESS(reset,clk) 
	  BEGIN  
	    IF reset='1'THEN  
			state<=S0; 
		ELSIF (clk 'EVENT AND clk='1')THEN 
			CASE state IS  
				WHEN S0=> 
							IF w1='1'THEN 
								state<=S1;	 
							END IF; 
                WHEN S1=> 
							IF w2='1'THEN 
								state<=S2;	 
							END IF; 
				WHEN S2=> 
							IF w3='1'THEN 
								state<=S3;	 
							END IF; 
				WHEN S3=> 
							IF w2='1'THEN 
								state<=S0;	 
							END IF; 
			END CASE; 
		END IF; 
	  END PROCESS; 
	  c1<='1'  WHEN state=S0 ELSE '0'; 
	  c2<='1'  WHEN state=S1 OR state=S3 ELSE '0'; 
	  c3<='1'  WHEN state=S2 ELSE '0'; 
	  r1<='1'  WHEN state=S1 OR state=S0 ELSE '0'; 
	  y1<='1'  WHEN state=S3 ELSE '0'; 
	  g1<='1'  WHEN state=S2 ELSE '0'; 
	  r2<='1'  WHEN state=S2 OR state=S3 ELSE '0'; 
	  y2<='1'  WHEN state=S1 ELSE '0'; 
	  g2<='1'  WHEN state=S0 ELSE '0'; 
	 END a;