帮我编程，使用vhdl语言4×4键盘阵列控制八位数码管显示

好的，下面是一个使用VHDL语言实现4×4键盘阵列控制八位数码管显示的示例代码：

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;

entity keyboard_display is
    Port ( clk : in  STD_LOGIC;
           row : in  STD_LOGIC_VECTOR (3 downto 0);
           col : out STD_LOGIC_VECTOR (3 downto 0);
           data_out : out STD_LOGIC_VECTOR (7 downto 0);
           enable : out STD_LOGIC);
end keyboard_display;

architecture Behavioral of keyboard_display is

    signal key_pressed : STD_LOGIC_VECTOR(15 downto 0); -- 记录键盘按下的状态
    signal row_sel : STD_LOGIC_VECTOR(3 downto 0); -- 用于扫描行
    signal col_sel : STD_LOGIC_VECTOR(3 downto 0); -- 用于扫描列
    signal data_in : STD_LOGIC_VECTOR(15 downto 0); -- 用于存储键盘输入的值
    
    type state_type is (INIT, SCAN_ROW, SCAN_COL, DISPLAY); --定义状态类型
    signal state : state_type := INIT; -- 定义状态变量

begin

    -- 按键扫描过程
    process(clk)
    begin
        if rising_edge(clk) then
            case state is
                when INIT =>
                    key_pressed <= (others => '0');
                    row_sel <= "1110";
                    col_sel <= "0111";
                    state <= SCAN_ROW;
                when SCAN_ROW =>
                    row_sel <= row_sel(2 downto 0) & '0';
                    col_sel <= "0111";
                    state <= SCAN_COL;
                when SCAN_COL =>
                    if col = "0110" then
                        col_sel <= col_sel(2 downto 0) & '0';
                        state <= DISPLAY;
                    else
                        col_sel <= col_sel(2 downto 0) & '1';
                        state <= SCAN_ROW;
                    end if;
                when DISPLAY =>
                    data_in <= key_pressed;
                    state <= INIT;
            end case;
        end if;
    end process;
    
    -- 按键状态检测过程
    process(clk)
    begin
        if rising_edge(clk) then
            if row = row_sel and col = col_sel then
                key_pressed <= key_pressed(14 downto 0) & '1';
            else
                key_pressed <= key_pressed(14 downto 0) & '0';
            end if;
        end if;
    end process;
    
    -- 数码管显示过程
    process(clk)
    begin
        if rising_edge(clk) then
            if state = DISPLAY then
                case data_in(3 downto 0) is
                    when "0000" => data_out <= "00111111"; -- 显示0
                    when "0001" => data_out <= "00000110"; -- 显示1
                    when "0010" => data_out <= "01011011"; -- 显示2
                    when "0011" => data_out <= "01001111"; -- 显示3
                    when "0100" => data_out <= "01100110"; -- 显示4
                    when "0101" => data_out <= "01101101"; -- 显示5
                    when "0110" => data_out <= "01111101"; -- 显示6
                    when "0111" => data_out <= "00000111"; -- 显示7
                    when "1000" => data_out <= "01111111"; -- 显示8
                    when "1001" => data_out <= "01101111"; -- 显示9
                    when others => data_out <= "11111111"; -- 不显示
                end case;
                enable <= '0'; -- 开启显示
            else
                data_out <= "11111111"; -- 不显示
                enable <= '1'; -- 关闭显示
            end if;
        end if;
    end process;

end Behavioral;

这个代码实现了4×4键盘阵列的扫描和八位数码管的显示。你可以根据自己的需求进行修改和调试。