这是评论而不是答案,因为我还没有资格发表评论,所以我将其作为答案。
我认为您在 FSM 概念中存在一些问题。同样如评论中所说, data_in 是 std_logic 而不是向量。您一次输入一位串行输入,因此请相应地编写流程。您可以编写代码来检测序列 BDA、BAA、BAD,即序列“011100”、“010000”和“010011”。我会写一个简单的 FSM 代码,这样你就可以清除你的概念,然后你可以尝试。
library ieee;
use IEEE.std_logic_1164.all;
entity mealy is
port (clk : in std_logic;
reset : in std_logic;
input : in std_logic;
output : out std_logic
);
end mealy;
architecture behavioral of mealy is
type state_type is (s0,s1,s2,s3); --type of state machine.
signal current_s,next_s: state_type; --current and next state declaration.
begin
process (clk,reset)
begin
if (reset='1') then
current_s <= s0; --default state on reset.
elsif (rising_edge(clk)) then
current_s <= next_s; --state change.
end if;
end process;
--state machine process.
process (current_s,input)
begin
case current_s is
when s0 => --when current state is "s0"
if(input ='0') then
output <= '0';
next_s <= s1;
else
output <= '1';
next_s <= s2;
end if;
when s1 =>; --when current state is "s1"
if(input ='0') then
output <= '0';
next_s <= s3;
else
output <= '0';
next_s <= s1;
end if;
when s2 => --when current state is "s2"
if(input ='0') then
output <= '1';
next_s <= s2;
else
output <= '0';
next_s <= s3;
end if;
when s3 => --when current state is "s3"
if(input ='0') then
output <= '1';
next_s <= s3;
else
output <= '1';
next_s <= s0;
end if;
end case;
end process;
end behavioral;