vhdl4x4矩阵键盘扫描

下面是一个简单的 VHDL 代码，用于扫描 4x4 矩阵键盘：

entity matrix_keyboard is
    port (
        ROW : in std_logic_vector(3 downto 0);
        COL : out std_logic_vector(3 downto 0);
        KEY : out std_logic_vector(15 downto 0)
    );
end matrix_keyboard;

architecture Behavioral of matrix_keyboard is

    signal ROW_temp : std_logic_vector(3 downto 0);
    signal KEY_temp : std_logic_vector(15 downto 0);

begin

    ROW_temp <= ROW;

    process (ROW_temp)
    begin
        case ROW_temp is
            when "1110" =>
                KEY_temp <= "1111111111111110";
            when "1101" =>
                KEY_temp <= "1111111111101111";
            when "1011" =>
                KEY_temp <= "1111111111011111";
            when "0111" =>
                KEY_temp <= "1111111110111111";
            when others =>
                KEY_temp <= "1111111111111111";
        end case;
    end process;

    COL <= not ((KEY_temp and ROW) or (not KEY_temp and not ROW));
    KEY <= KEY_temp;

end Behavioral;

在这个代码中，ROW 是输入，COL 和 KEY 是输出。ROW 是一个 4 位向量，用于选择要扫描的行。COL 是一个 4 位向量，用于输出列的状态。KEY 是一个 16 位向量，用于输出每个键的状态。