各种触发器的VHDL程序.doc

题目：写出带异步复位边沿（下降沿）JK触发器的VHDL程序：
LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
ENTITY jk1 is
PORT (clk,R,S : IN STD_LOGIC;
j,k: IN STD_LOGIC;
q,qn : OUT STD_LOGIC);
END jk1;
ARCHITECTURE one OF jk1 IS
SIGNAL q_s : STD_LOGIC;
BEGIN
PROCESS (R,S,clk,j,k)
BEGIN
IF (R='1' AND S='0') THEN q_s<='0';
ELSIF(R='0' AND S='1') THEN q_s<='1';
ELSIF clk'EVENT AND clk='0' THEN
IF (J='0' AND k='0') THEN
q_s<= q_s;
ELSIF (J='0' AND k='1')THEN
q_s<='0';
ELSIF (J='1' AND k='0')THEN
q_s<='1';
ELSIF (J='1' AND k='1') THEN
q_s<=NOT q_s;
END IF;
END IF;
END PROCESS;
q<=q_s;
qn<=not q_s;
END one;

基本RS触发器
entity rsff is
port(r,s:in std_logic;
q,qb:out std_logic);
end rsff;
architecture rtl of rsff is
signal q_temp,qb_temp:std_logic;
begin
process(r,s)
begin
if(s='1' and r='0')then
q_temp<='1';
qb_temp<='0';
elsif(s='0' and r='1')then
q_temp<='0';
qb_temp<='1';
else
q_temp<=q_temp;
qb_temp<=qb_temp;
end if;
end process;
q<=q_temp;
qb<=qb_temp;
end rtl;

. 同步RS触发器
library ieee;
use ieee.std_logic_1164.all;
entity synrsff is
port(clk,r,s:in std_logic;
q,qb:out std_logic);
end synrsff;
architecture rtl of synrsff is
signal q_temp,qb_temp:std_logic;
begin
process(clk,r,s)
begin
if(clk='1')then
if(s='1' and r='0')then
q_temp<='1';
qb_temp<='0';
elsif(s='0' and r='1')then
q_temp<='0';
qb_temp<='1';
else
q_temp<=q_temp;
qb_temp<=qb_temp;
end if;
else
q_temp<=q_temp;
qb_temp<=qb_temp;
end if;
end process;
q<=q_temp;
qb<=qb_temp;
end rtl;

. 同步D触发器
library ieee;
use ieee.std_logic_1164.all;
entity synd is
port(clk,d:in std_logic;
q,qb:out std_logic);
end synd;
architecture rtl of synd is
signal q_temp,qb_temp:std_logic;
begin
process(clk)
begin
if(clk='1')then
q_temp<=d;
qb_temp<=not d;
else
q_temp<=q_temp;
qb_temp<=qb_temp;
end if;
end process;
q<=q_temp;
qb<=qb_temp;
end rtl;

带异步置位复位边沿（上升沿）D触发器
library ieee;
use ieee.std_logic_1164.all;
entity adff is
port(clk,d,r,s:in std_logic;
q,qb:out std_logic);
end adff;
architecture rtl of adff is
signal q_temp,qb_temp:std_logic;
begin
process(clk,r,s)
begin
if(r='0' and s='1')then
q_temp<='1';
qb_temp<='0';
elsif(r='1' and s='0')then
q_temp<='0';
qb_temp<='1';
elsif(clk'event and clk='1')then
q_temp<=d;
qb_temp<=not d;
end if;
end process;
q<=q_temp;
qb<=qb_temp;
end rtl;