VHDL硬件描述语言实现数字钟

--VHDL上机的一个作业，程序太长实验报告册上写不下了。于是就在博客上留一份吧。
LIBRARY IEEE;

USE IEEE.STD_LOGIC_1164.ALL;

USE IEEE.STD_LOGIC_UNSIGNED.ALL;



ENTITY CLOCK IS

PORT(CLK1S,SET,SWC,CLK1MS,RST:IN STD_LOGIC;

    S0,S1,M0,M1,H0,H1:OUT STD_LOGIC_VECTOR(3 DOWNTO 0);

    BEEP:OUT STD_LOGIC;

    PNS,PSS,PSM,PSH:OUT STD_LOGIC

);

END CLOCK;



ARCHITECTURE ONE OF CLOCK IS

SIGNAL CS,CM:STD_LOGIC;--,CM

SIGNAL CLKSI,CLKMI,CLKHI:STD_LOGIC;

SIGNAL NS,SS,SM,SH:STD_LOGIC;

BEGIN

PSS<=SS;

PSM<=SM;

PSH<=SH;

PNS<=NS;

PROCESS(SWC,RST)

VARIABLE STAT:STD_LOGIC_VECTOR(1 DOWNTO 0);

BEGIN

IF(RST='1')THEN

STAT:="00";

NS<='1';

SS<='0';

SM<='0';

SH<='0';

ELSIF(RISING_EDGE(SWC))THEN

STAT:=STAT+1;

CASE STAT IS

WHEN"00"=>

NS<='1';

SS<='0';

SM<='0';

SH<='0';

WHEN"01"=>

NS<='0';

SS<='1';

SM<='0';

SH<='0';

WHEN"10"=>

NS<='0';

SS<='0';

SM<='1';

SH<='0';

WHEN"11"=>

NS<='0';

SS<='0';

SM<='0';

SH<='1';

WHEN OTHERS=>

STAT:="00";

END CASE;

END IF;

END PROCESS;



CLKSI<=(CLK1S AND NS) OR (SS AND SET);

CLKMI<=CS OR (SM AND SET);

CLKHI<=CM OR (SH AND SET);



PROCESS(CLKSI,RST,SET,NS)

VARIABLE SS0,SS1:STD_LOGIC_VECTOR(3 DOWNTO 0);

BEGIN

IF(RST='1')THEN

SS0:="0000";

SS1:="0000";

CS<='0';

--CM<='0';

ELSIF(RISING_EDGE(CLKSI))THEN

SS0:=SS0+1;

IF(SS0="1010")THEN

SS0:="0000";

SS1:=SS1+1;

END IF;

IF(SS1="0110")THEN

SS1:="0000";

--SM0:=SM0+1;

CS<='1';

ELSE

CS<='0';

END IF;

END IF;

S0<=SS0;

S1<=SS1;

END PROCESS;



PROCESS(RST,CLKMI,SET)

VARIABLE SM0,SM1:STD_LOGIC_VECTOR(3 DOWNTO 0);

BEGIN

IF(RST='1')THEN

SM0:="0000";

SM1:="0000";

CM<='0';

ELSIF(RISING_EDGE(CLKMI))THEN

SM0:=SM0+1;

IF(SM0="1010")THEN

SM0:="0000";

SM1:=SM1+1;

END IF;

IF(SM1="0110")THEN

SM1:="0000";

CM<='1';

ELSE

CM<='0';

END IF;

END IF;

M0<=SM0;

M1<=SM1;

END PROCESS;



PROCESS(RST,CLKHI,SET)

VARIABLE SH0,SH1:STD_LOGIC_VECTOR(3 DOWNTO 0);

BEGIN

IF(RST='1')THEN

SH0:="0000";

SH1:="0000";

ELSIF(RISING_EDGE(CLKHI))THEN

SH0:=SH0+1;

IF(SH0="1010")THEN

SH0:="0000";

SH1:=SH1+1;

END IF;

IF(SH1="0010" AND SH0="0100")THEN

SH1:="0000";

SH0:="0000";

END IF;

END IF;

H0<=SH0;

H1<=SH1;

END PROCESS;



PROCESS(CM,CS)

BEGIN

IF(CM='1' AND CS='1')THEN

BEEP<=CLK1MS;

ELSE

BEEP<='0';

END IF;

END PROCESS;

END ONE;