vhdl按下按键后生成随机数并显示在数码管上

您可以使用以下代码实现：

library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;

entity random_number_generator is
    port (
        clk: in std_logic;
        reset: in std_logic;
        button: in std_logic;
        display: out std_logic_vector(3 downto 0)
    );
end entity random_number_generator;

architecture rtl of random_number_generator is
    signal counter: unsigned(3 downto 0) := (others => '0');
    signal seed: unsigned(3 downto 0) := (others => '0');
    signal random_number: unsigned(3 downto 0) := (others => '0');
begin
    process(clk, reset)
    begin
        if reset = '1' then
            counter <= (others => '0');
            seed <= (others => '0');
            random_number <= (others => '0');
            display <= (others => '0');
        elsif rising_edge(clk) then
            if button = '1' then
                seed <= seed + 1;
            end if;
            if counter = 0 then
                random_number <= seed;
                display <= std_logic_vector(to_unsigned(random_number, 4));
            else
                random_number <= random_number xor (random_number sll 1);
            end if;
            counter <= counter + 1;
        end if;
    end process;
end architecture rtl;

这个代码实现了一个随机数生成器，当按下按钮时，它会使用一个种子值生成一个随机数，并将其显示在数码管上。每次按下按钮，种子值都会增加1，以产生不同的随机数序列。