状态机按键消抖VHDl代码

状态机按键消抖是一种常用的技术，用于解决按键在物理上产生的抖动问题。下面是一个简单的状态机按键消抖的VHDL代码示例：

library ieee;
use ieee.std_logic_1164.all;

entity Debounce is
    port (
        clk : in std_logic;
        button : in std_logic;
        debounced_button : out std_logic
    );
end entity Debounce;

architecture Behavioral of Debounce is
    type state_type is (IDLE, PRESSED, RELEASED);
    signal current_state, next_state : state_type;
    signal button_stable : std_logic;
begin
    process (clk)
    begin
        if rising_edge(clk) then
            current_state <= next_state;
        end if;
    end process;

    process (current_state, button)
    begin
        case current_state is
            when IDLE =>
                if button = '0' then
                    next_state <= PRESSED;
                else
                    next_state <= IDLE;
                end if;
            when PRESSED =>
                if button = '1' then
                    next_state <= RELEASED;
                else
                    next_state <= PRESSED;
                end if;
            when RELEASED =>
                if button = '0' then
                    next_state <= PRESSED;
                else
                    next_state <= IDLE;
                end if;
        end case;
    end process;

    process (current_state)
    begin
        case current_state is
            when IDLE =>
                button_stable <= '0';
            when PRESSED =>
                button_stable <= '0';
            when RELEASED =>
                button_stable <= '1';
        end case;
    end process;

    debounced_button <= button_stable;
end architecture Behavioral;

上述代码中，使用了一个简单的三态状态机来实现按键消抖。状态机包含三个状态：IDLE（空闲）、PRESSED（按下）和RELEASED（释放）。根据当前状态和按键输入，确定下一个状态，并输出稳定的按键信号。