adcint.vhd

adcint,是adc0809的采样控制器设计!

LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
ENTITY ADCINT IS
PORT (D:IN STD_LOGIC_VECTOR(7 DOWNTO 0);
	CLK,EOC:IN STD_LOGIC;
	ALE,START,OE,ADDA,LOCK0:OUT STD_LOGIC;
	Q:OUT STD_LOGIC_VECTOR(7 DOWNTO 0));
END ADCINT;
ARCHITECTURE behav OF ADCINT IS
TYPE states IS (st0,st1,st2,st3,st4);
SIGNAL current_state,next_state:states:=st0;
SIGNAL REGL :STD_LOGIC_VECTOR(7 DOWNTO 0);
SIGNAL LOCK :STD_LOGIC;
BEGIN
      ADDA<='1';
Q<=REGL;LOCK0<=LOCK;
COM1:PROCESS(current_state,EOC) BEGIN
CASE current_state IS
WHEN st0=> next_state<=st1; 
WHEN st1=> next_state<=st2; 
WHEN st2=> IF(EOC='1')THEN next_state<=st3;
ELSE next_state<=st2;
END IF;
WHEN st3=> next_state<=st4;
WHEN st4=> next_state<=st0;
WHEN OTHERS=>next_state<=st0;
END CASE;
END PROCESS COM1;
COM2:PROCESS(current_state) BEGIN
CASE current_state IS
WHEN st0=>ALE<='0';START<='0';LOCK<='0';OE<='0';
WHEN st1=>ALE<='1';START<='1';LOCK<='0';OE<='0';
WHEN st2=>ALE<='0';START<='0';LOCK<='0';OE<='0';
WHEN st3=>ALE<='0';START<='0';LOCK<='0';OE<='1';
WHEN st4=>ALE<='0';START<='0';LOCK<='1';OE<='1';
WHEN OTHERS=>ALE<='0';START<='0';LOCK<='0';
END CASE;
END PROCESS COM2;
REG:PROCESS(CLK)
         BEGIN
         IF(CLK'EVENT AND CLK='1')THEN current_state<=next_state;
      END IF;
END PROCESS REG;
LATCH1:PROCESS(LOCK)
 BEGIN
           IF LOCK='1' AND LOCK'EVENT THEN REGL<=D;
         END IF;
        END PROCESS LATCH1;
END behav;