controller.vhd

CPLD控制交通灯程序

LIBRARY ieee;
USE ieee.std_logic_1164.all;
USE ieee.std_logic_unsigned.all;
ENTITY controller IS
	PORT
	(
		clock	: IN	STD_LOGIC;
		reset	: IN	STD_LOGIC;
		hold	: IN	STD_LOGIC;
		flash   : OUT	STD_LOGIC;
		numa,numb	: OUT	INTEGER RANGE 0 TO 25;
		reda,greena,yellowa: OUT STD_LOGIC;
		redb,greenb,yellowb: OUT STD_LOGIC
	);
END controller;

ARCHITECTURE a OF controller IS
SIGNAL countnum	: INTEGER RANGE 0 TO 50;
BEGIN
	PROCESS (clock)
	BEGIN
		IF reset = '0' THEN
			countnum <= 0;
		ELSIF rising_edge(clock) THEN
			IF hold = '0' THEN				
				flash <= '1';
			ELSE
				flash <= '0';
				IF countnum = 49 THEN
					countnum <= 0;
				ELSE
					countnum <= countnum+1;
				END IF;		
			END IF;
		END IF;
	END PROCESS;

	PROCESS (clock)
	BEGIN
	IF rising_edge(clock) THEN	
		IF hold = '0' THEN
			reda <= '1';
			redb <= '1';
			greena <= '0';
			greenb <= '0';
			yellowa <= '0';
			yellowb <= '0';
		ELSE
			IF countnum <= 19 THEN
				numa <= 20-countnum;
				reda <= '0';
				greena <= '1';
				yellowa <= '0';	
			ELSIF countnum <=24 THEN
				numa <= 25-countnum;	
				reda <= '0';
				greena <= '0';
				yellowa <= '1';	
			ELSE
				numa <= 50-countnum;	
				reda <= '1';
				greena <= '0';
				yellowa <= '0';
			END  IF;	
			IF countnum <=24 THEN
				numb <= 25-countnum;	
				redb <= '1';
				greenb <= '0';
				yellowb <= '0';	
			ELSIF countnum <=44 THEN
				numb <= 45-countnum;	
				redb <= '0';
				greenb <= '1';
				yellowb <= '0';	
			ELSE
				numb <= 50-countnum;	
				redb <= '0';
				greenb <= '0';
				yellowb <= '1';	
			END IF;
		END IF;
	END IF;																			
	END PROCESS;
END a;