minute.vhd

数字显示当前的小时、分钟、秒； 2、可以预置为12小时计时显示和24小时计时显示； 3、一个调节键

LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
USE IEEE.STD_LOGIC_UNSIGNED.ALL;
ENTITY MINUTE IS
PORT(CLK,RESET:IN STD_LOGIC;
     MIN1,MIN0:OUT STD_LOGIC_VECTOR(3 DOWNTO 0);
     COUT:OUT STD_LOGIC);
END MINUTE;
ARCHITECTURE MIN OF MINUTE IS
BEGIN 
PROCESS(CLK)
VARIABLE CNT1,CNT0:STD_LOGIC_VECTOR(3 DOWNTO 0);
BEGIN
IF RESET='1' THEN----当CKR为1时，高低位均为0
CNT1:="0000";
CNT0:="0000";
ELSIF CLK'EVENT AND CLK='1' THEN
IF CNT1="0101" AND CNT0="1000" THEN
COUT<='1';
CNT0:="1001";
ELSIF CNT0<"1001" THEN
CNT0:=CNT0+1;
ELSE
CNT0:="0000";
IF CNT1<"0101" THEN
CNT1:=CNT1+1;
ELSE
CNT1:="0000";
COUT<='0';
END IF;
END IF;
END IF;
MIN1<=CNT1;
MIN0<=CNT0;
END PROCESS;
END MIN;