利用蜂鸣器弹奏每秒的歌曲：
LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
USE IEEE.STD_LOGIC_UNSIGNED.ALL;
ENTITY beep1 IS
PORT(
CLK:IN STD_LOGIC;
-- DIGIT:BUFFER STD_LOGIC_VECTOR(6 DOWNTO 0);
SPEAKER :OUT STD_LOGIC);
END ENTITY;
ARCHITECTURE SONG OF beep1 IS
SIGNAL DRIVER,ORIGIN:STD_LOGIC_VECTOR(12 DOWNTO 0);
SIGNAL COUNTER:INTEGER RANGE 0 TO 140;
SIGNAL COUNTER1:INTEGER RANGE 0 TO 3;
SIGNAL COUNTER2:INTEGER RANGE 1 TO 10000000;
SIGNAL DIGIT :STD_LOGIC_VECTOR(6 DOWNTO 0);
SIGNAL COUNT :STD_LOGIC_VECTOR(1 DOWNTO 0);
SIGNAL CARRIER,CLK_4MHZ,CLK_4HZ:STD_LOGIC;
BEGIN
PROCESS(CLK)
BEGIN
IF CLK'EVENT AND CLK='1' THEN
IF COUNTER1=1 THEN CLK_4MHZ<='1';
COUNTER1<=2;
ELSIF COUNTER1=3 THEN CLK_4MHZ<='0';
COUNTER1<=0;
ELSE COUNTER1<=COUNTER1+1;
END IF;
IF COUNTER2=5000000 THEN CLK_4HZ<='1';
COUNTER2<=5000001;
ELSIF COUNTER2=10000000 THEN CLK_4HZ<='0';
COUNTER2<=1;
ELSE COUNTER2<=COUNTER2+1;
END IF;
END IF;
END PROCESS;
PROCESS(CLK_4MHZ)
BEGIN
IF CLK_4MHZ'EVENT AND CLK_4MHZ='1' THEN
IF DRIVER="1111111111111"THEN
CARRIER<='1';
DRIVER<=ORIGIN;
ELSE
DRIVER<=DRIVER+1;
CARRIER<='0';
END IF;
END IF;
END PROCESS;
PROCESS(CARRIER)
BEGIN
IF CARRIER'EVENT AND CARRIER='1' THEN
COUNT<=COUNT+1;
IF COUNT="00"THEN
SPEAKER<='1';
ELSE
SPEAKER<='0';
END IF;
END IF;
END PROCESS;
PROCESS(CLK_4HZ)
BEGIN
IF CLK_4HZ'EVENT AND CLK_4HZ='1' THEN
IF COUNTER=140 THEN
COUNTER<=0;
ELSE COUNTER<=COUNTER+1;
END IF;
END IF;
CASE COUNTER IS
WHEN 0 =>DIGIT<="0000011"; WHEN 1 =>DIGIT<="0000011";
WHEN 2 =>DIGIT<="0000011"; WHEN 3 =>DIGIT<="0000011";
WHEN 4 =>DIGIT<="0000101"; WHEN 5 =>DIGIT<="0000101";
WHEN 6 =>DIGIT<="0000101"; WHEN 7 =>DIGIT<="0000110";
WHEN 8 =>DIGIT<="0001000"; WHEN 9 =>DIGIT<="0001000";
WHEN 10 =>DIGIT<="0001000"; WHEN 11 =>DIGIT<="0010000";
WHEN 12 =>DIGIT<="0000110"; WHEN 13 =>DIGIT<="0001000";
WHEN 14 =>DIGIT<="0000101"; WHEN 15 =>DIGIT<="0000101";
WHEN 16 =>DIGIT<="0101000"; WHEN 17 =>DIGIT<="0101000";
WHEN 18 =>DIGIT<="0101000"; WHEN 19 =>DIGIT<="1000000";
WHEN 20 =>DIGIT<="0110000"; WHEN 21 =>DIGIT<="0101000";
WHEN 22 =>DIGIT<="0011000"; WHEN 23 =>DIGIT<="0101000";
WHEN 24 =>DIGIT<="0010000"; WHEN 25 =>DIGIT<="0010000";
WHEN 26 =>DIGIT<="0010000"; WHEN 27 =>DIGIT<="0010000";
WHEN 28 =>DIGIT<="0010000"; WHEN 29 =>DIGIT<="0010000";
WHEN 30 =>DIGIT<="0000011"; WHEN 31 =>DIGIT<="0000000";
WHEN 32 =>DIGIT<="0010000"; WHEN 33 =>DIGIT<="0010000";
WHEN 34 =>DIGIT<="0010000"; WHEN 35 =>DIGIT<="0011000";
WHEN 36 =>DIGIT<="0000111"; WHEN 37 =>DIGIT<="0000111";
WHEN 38 =>DIGIT<="0000110"; WHEN 39 =>DIGIT<="0000110";
WHEN 40 =>DIGIT<="0000101"; WHEN 41 =>DIGIT<="0000101";
WHEN 42 =>DIGIT<="0000101"; WHEN 43 =>DIGIT<="0000110";
WHEN 44 =>DIGIT<="0001000"; WHEN 45 =>DIGIT<="0001000";
WHEN 46 =>DIGIT<="0010000"; WHEN 47 =>DIGIT<="0010000";
WHEN 48 =>DIGIT<="0000011"; WHEN 49 =>DIGIT<="0000011";
WHEN 50 =>DIGIT<="0001000"; WHEN 51 =>DIGIT<="0001000";
WHEN 52 =>DIGIT<="0000110"; WHEN 53 =>DIGIT<="0000101";
WHEN 54 =>DIGIT<="0000110"; WHEN 55 =>DIGIT<="0001000";
WHEN 56 =>DIGIT<="0000101"; WHEN 57 =>DIGIT<="0000101";
WHEN 58 =>DIGIT<="0000101"; WHEN 59 =>DIGIT<="0000101";
WHEN 60 =>DIGIT<="0000101"; WHEN 61 =>DIGIT<="0000101";
WHEN 62 =>DIGIT<="0000101"; WHEN 63 =>DIGIT<="0000101";
WHEN 64 =>DIGIT<="0011000"; WHEN 65 =>DIGIT<="0011000";
WHEN 66 =>DIGIT<="0011000"; WHEN 67 =>DIGIT<="0101000";
WHEN 68 =>DIGIT<="0000111"; WHEN 69 =>DIGIT<="0000111";
WHEN 70 =>DIGIT<="0010000"; WHEN 71 =>DIGIT<="0010000";
WHEN 72 =>DIGIT<="0000110"; WHEN 73 =>DIGIT<="0001000";
WHEN 74 =>DIGIT<="0000101"; WHEN 75 =>DIGIT<="0000101";
WHEN 76 =>DIGIT<="0000101"; WHEN 77 =>DIGIT<="0000101";
WHEN 78 =>DIGIT<="0000101"; WHEN 79 =>DIGIT<="0000101";
WHEN 80 =>DIGIT<="0000011"; WHEN 81 =>DIGIT<="0000101";
WHEN 82 =>DIGIT<="0000011"; WHEN 83 =>DIGIT<="0000011";
WHEN 84 =>DIGIT<="0000101"; WHEN 85 =>DIGIT<="0000110";
WHEN 86 =>DIGIT<="0000111"; WHEN 87 =>DIGIT<="0010000";
WHEN 88 =>DIGIT<="0000110"; WHEN 89 =>DIGIT<="0000110";
WHEN 90 =>DIGIT<="0000110"; WHEN 91 =>DIGIT<="0000110";
WHEN 92 =>DIGIT<="0000110"; WHEN 93 =>DIGIT<="0000110";
WHEN 94 =>DIGIT<="0000101"; WHEN 95 =>DIGIT<="0000110";
WHEN 96 =>DIGIT<="0001000"; WHEN 97 =>DIGIT<="0001000";
WHEN 98 =>DIGIT<="0001000"; WHEN 99 =>DIGIT<="0010000";
WHEN 100=>DIGIT<="0101000"; WHEN 101=>DIGIT<="0101000";
WHEN 102=>DIGIT<="0101000"; WHEN 103=>DIGIT<="0011000";
WHEN 104=>DIGIT<="0010000"; WHEN 105=>DIGIT<="0010000";
WHEN 106=>DIGIT<="0011000"; WHEN 107=>DIGIT<="0010000";
WHEN 108=>DIGIT<="0001000"; WHEN 109=>DIGIT<="0001000";
WHEN 110=>DIGIT<="0000110"; WHEN 111=>DIGIT<="0000101";
WHEN 112=>DIGIT<="0000011"; WHEN 113=>DIGIT<="0000011";
WHEN 114=>DIGIT<="0000011"; WHEN 115=>DIGIT<="0000011";
WHEN 116=>DIGIT<="0001000"; WHEN 117=>DIGIT<="0001000";
WHEN 118=>DIGIT<="0000110"; WHEN 119=>DIGIT<="0001000";
WHEN 120=>DIGIT<="0000110"; WHEN 121=>DIGIT<="0000011";
WHEN 122=>DIGIT<="0000011"; WHEN 123=>DIGIT<="0010000";
WHEN 124=>DIGIT<="0000011"; WHEN 125=>DIGIT<="0000101";
WHEN 126=>DIGIT<="0000110"; WHEN 127=>DIGIT<="0001000";
WHEN 128=>DIGIT<="0000101"; WHEN 129=>DIGIT<="0000101";
WHEN 130=>DIGIT<="0000101"; WHEN 131=>DIGIT<="0000101";
WHEN 132=>DIGIT<="0000101"; WHEN 133=>DIGIT<="0000101";
WHEN 134=>DIGIT<="0000101"; WHEN 135=>DIGIT<="0000101";
WHEN 136=>DIGIT<="0000000"; WHEN 137=>DIGIT<="0000000";
WHEN 138=>DIGIT<="0000000"; WHEN 139=>DIGIT<="0000000";
WHEN OTHERS=>DIGIT<="0000000";
END CASE;
CASE DIGIT IS
WHEN "0000011"=>ORIGIN<="0100001001100";
WHEN "0000101"=>ORIGIN<="0110000010001";
WHEN "0000110"=>ORIGIN<="0111000111110";
WHEN "0000111"=>ORIGIN<="1000000101101";
WHEN "0001000"=>ORIGIN<="1000100010001";
WHEN "0010000"=>ORIGIN<="1001010110010";
WHEN "0011000"=>ORIGIN<="1010000100101";
WHEN "0101000"=>ORIGIN<="1011000001000";
WHEN "0110000"=>ORIGIN<="1011100011110";
WHEN "1000000"=>ORIGIN<="1100010001000";
WHEN OTHERS=>ORIGIN<="1111111111111";
END CASE;
END PROCESS;
END SONG;
