ztja.vhd

在maxplusII上用VHDL语言编程实现的数字基带信号的同步提取

library IEEE;
use IEEE.std_logic_1164.all;
USE IEEE.STD_LOGIC_ARITH.ALL;
USE IEEE.STD_LOGIC_UNSIGNED.ALL;

entity ztja is
	port (
		reset : in std_logic;
        en : in std_logic;
        keyin : in std_logic_vector (31 downto 0);
		keyvalue : in std_logic_vector (3 downto 0);
		keyout1 : out std_logic;
        keyout2 : out std_logic;
        keyout3 : out std_logic;
        keyout4 : out std_logic;
        z,clr : out std_logic );
end entity;
architecture ztja_arch of ztja is
type mystate is (s0,s1,s2,s3,s4);
signal m_state:mystate;
signal a: std_logic_vector (31 downto 0);
signal b: std_logic_vector (31 downto 0);
begin

process(en,m_state,reset)
begin

if reset='0' then
b<=X"00000001";
m_state<=s0;
elsif (en'event and en='1')then
a<=keyin;
	case m_state is
      when s0=>clr<='0';
	         if(keyvalue="1010") then         
				m_state<=s2;
               else
                m_state<=s0; 
                end if;
    when s2=>if(b=keyin) then
                  clr<='1';
                    m_state<=s3;
				else
                   clr<='1';
                  m_state<=s0;
                  end if;
    when s3=>--if (keyvalue="1101") then
               -- m_state<=s4;
                 --else m_state<=s0;
--end if;
                --elsif(keyvalue="1110")then
                --m_state<=s1;
               --else  m_state<=s0;
             --end if;


           case keyvalue is
            when "1101"=>m_state<=s4;
            when "1110"=>m_state<=s1;
            when others=>m_state<=s0;
            end case;
    when s4=>if keyvalue="1111" then
                m_state<=s0;
              end if;
	when s1=>clr<='0';
          b<=keyin;
		if keyvalue="1011" then
            clr<='1';
          m_state<=s0;
         
		--end if;
		end if;
	end case;
end if;
end process;


keyout1<='1'when m_state=s0
else '0';

keyout2<='1'when m_state=s3

else '0';
keyout3<='1'when m_state=s4

else '0';
keyout4<='1'when m_state=s1

else '0';

z<='1'when m_state=s4
else '0';
end ztja_arch;