light_produce.vhd

用VHDL语言编写

--产生交通灯信号
--
--端口说明
	--reset		: 复位信号reset = '1'时复位 
	--control	: 控制信号输入
	--sn_ew_rgy	: 交通灯输出

LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
USE IEEE.STD_LOGIC_UNSIGNED.ALL;

ENTITY light_produce IS
	PORT(
		reset		: IN	STD_LOGIC;
		control		: IN	STD_LOGIC;
		sn_ew_rgy	: OUT	STD_LOGIC_VECTOR(5 DOWNTO 0));
END light_produce;

ARCHITECTURE light_produce_run OF light_produce IS
	--control_mid = "00""01""10""11"
	SIGNAL control_mid : STD_LOGIC_VECTOR(2 DOWNTO 0);
BEGIN
	PROCESS (reset,control)
	BEGIN
		IF (reset = '1') THEN
		    control_mid <= "111";
		ELSIF (control'EVENT AND control = '1') THEN
		    IF (control_mid = "011") THEN
		    	control_mid <= "000";
		    ELSE
		    	control_mid <= control_mid+'1';
		    END IF;
		END IF;
	END PROCESS;
	
	sn_ew_rgy <= "100010" WHEN control_mid ="000" ELSE
				 "100001" WHEN control_mid ="001" ELSE
				 "010100" WHEN control_mid ="010" ELSE
				 "001100" WHEN control_mid ="011" ELSE
				 "100100" ;
END light_produce_run;