D触发器
代码语言：javascript复制LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
ENTITY dtrigger IS
PORT(d,clk:IN STD_LOGIC;
q,dq:OUT STD_LOGIC);
END dtrigger;
ARCHITECTURE dtrigger_behavior OF dtrigger IS
BEGIN
PROCESS(clk)
BEGIN
IF(clk'EVENT AND clk='1')THEN --上升沿触发
q<=d;
dq<=NOT d;
END IF;
END PROCESS;
END dtrigger_behavior;同步复位D触发器
代码语言：javascript复制LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
ENTITY dtrigger IS
PORT(d,clk,rst:IN STD_LOGIC;
q,dq:OUT STD_LOGIC);
END dtrigger;
ARCHITECTURE dtrigger_behavior OF dtrigger IS
BEGIN
PROCESS(clk)
BEGIN
IF(clk'EVENT AND clk='1')THEN
IF(rst='1')THEN --同步复位
q<='0';
dq<='1';
ELSE
q<=d;
dq<=NOT d;
END IF;
END IF;
END PROCESS;
END dtrigger_behavior;异步置位D触发器
代码语言：javascript复制LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
ENTITY dtrigger IS
PORT(d,clk,rst:IN STD_LOGIC;
q,dq:OUT STD_LOGIC);
END dtrigger;
ARCHITECTURE dtrigger_behavior OF dtrigger IS
BEGIN
PROCESS(clk)
BEGIN
IF(rst='1')THEN
q<='0';
dq<='1';
ELSIF(clk'EVENT AND clk='1')THEN
q<=d;
dq<= NOT d;
END IF;
END PROCESS;
END dtrigger_behavior;同步复位就是在时钟边沿来临的时候，复位信号才有作用。而异步复位则是复位信号一旦有效触发器就立即复位，而不是等待时钟边沿的来临。
D锁存器
代码语言：javascript复制LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
ENTITY dlock IS
PORT(clk,d:IN STD_LOGIC;
q:OUT STD_LOGIC);
END dlock;
ARCHITECTURE dlock_behavior OF dlock IS
BEGIN
PROCESS(clk)
BEGIN
IF(clk='1')THEN
q<=d;
END IF;
END PROCESS;
END dlock_behavior;
