keyin.vhd

采用MaxPlusII写的一个小时钟程序

LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
USE IEEE.STD_LOGIC_ARITH.ALL;

ENTITY keyin IS
	PORT(reset_sw,start_stop_sw,keyclk,clk:IN STD_ULOGIC;
		 res,stst:OUT STD_ULOGIC);
END keyin;

ARCHITECTURE rtl OF keyin IS
	SIGNAL res0,res1,stst0,stst1:STD_LOGIC;
BEGIN
	PROCESS(keyclk)
		BEGIN 	
			IF (keyclk 'EVENT AND keyclk='0') THEN
				res1<=res0;
				res0<=reset_sw;
				stst1<=stst0;
				stst0<=start_stop_sw;
			END IF;
	END PROCESS;
	PROCESS(res0,res1,stst0,stst1)
		BEGIN
			res<=keyclk AND res0 AND (NOT res1);
			stst<=keyclk AND stst0 AND (NOT stst1);
	END PROCESS;
END rtl;