dfre2.vhd

设计一个五路呼叫器,具体设计要求如下: 1．五个按键模拟五个呼叫源 2．当有一个按键按下时

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

ENTITY DFRE2 IS
	PORT(iclk : IN STD_LOGIC;
		 oclk : OUT STD_LOGIC);
END DFRE2;

ARCHITECTURE run OF DFRE2 IS
	BEGIN
	PROCESS (iclk)
	VARIABLE fre: STD_LOGIC_VECTOR(25 DOWNTO 0);
	VARIABLE OC : STD_LOGIC; 
	BEGIN
	IF iclk'EVENT AND iclk = '1'
	THEN IF fre = "01011111010111100001000000"
		THEN fre := "00000000000000000000000000";
			  OC := NOT OC;
		ELSE fre := fre + '1';
		END IF;
	END IF;
	oclk <= OC;
	END PROCESS;
END run;