VHDL写FPGA数码管静态显示单个数字

以下是一个简单的VHDL代码示例，用于在FPGA上实现静态显示单个数字的数码管：

entity num_display is
    port(
        clk : in std_logic;
        num : in integer range 0 to 9;
        seg : out std_logic_vector(6 downto 0);
        anode : out std_logic
    );
end entity num_display;

architecture Behavioral of num_display is
begin
    case num is
        when 0 =>
            seg <= "0000001"; -- 0
        when 1 =>
            seg <= "1001111"; -- 1
        when 2 =>
            seg <= "0010010"; -- 2
        when 3 =>
            seg <= "0000110"; -- 3
        when 4 =>
            seg <= "1001100"; -- 4
        when 5 =>
            seg <= "0100100"; -- 5
        when 6 =>
            seg <= "0100000"; -- 6
        when 7 =>
            seg <= "0001111"; -- 7
        when 8 =>
            seg <= "0000000"; -- 8
        when 9 =>
            seg <= "0000100"; -- 9
        when others =>
            seg <= "1111111"; -- error
    end case;

    anode <= '1';
end architecture Behavioral;

在这个示例中，我们用一个 `num` 输入来指定要显示的数字，然后使用一个 `case` 语句来为该数字设置相应的七段数码管输出 `seg`。如果输入数字不在 0 到 9 的范围内，则在 `case` 语句的 `others` 分支中输出错误信号。

最后，我们通过 `anode` 输出激活信号，使得该数字在数码管上静态显示。