用VHDL编写的LCD1602显示程序

好的，以下是一个简单的用VHDL编写的LCD1602显示程序，你可以参考一下：

library ieee;
use ieee.std_logic_1164.all;

entity lcd1602 is
    port (
        clk     : in std_logic;
        rst     : in std_logic;
        rs      : out std_logic;
        rw      : out std_logic;
        en      : out std_logic;
        data    : out std_logic_vector(7 downto 0);
        e       : out std_logic_vector(1 downto 0)
    );
end entity;

architecture rtl of lcd1602 is
    signal count : integer range 0 to 100000 := 0;
    signal i     : integer range 0 to 15 := 0;

    type states is (idle, init, write_cmd, write_data);
    signal state : states := idle;

    signal cmd   : std_logic_vector(7 downto 0) := "00000001";
    signal text  : std_logic_vector(7 downto 0) := "01010101";

begin
    process(clk, rst)
    begin
        if rst = '1' then
            state <= idle;
            count <= 0;
            i <= 0;
            rs <= '0';
            rw <= '0';
            en <= '0';
            data <= (others => '0');
            e <= "00";
        elsif rising_edge(clk) then
            case state is
                when idle =>
                    count <= 0;
                    i <= 0;
                    rs <= '0';
                    rw <= '0';
                    en <= '0';
                    data <= (others => '0');
                    e <= "00";
                    if count = 100000 then
                        state <= init;
                    else
                        count <= count + 1;
                    end if;

                when init =>
                    rs <= '0';
                    rw <= '0';
                    en <= '1';
                    data <= "00111000";
                    e <= "01";
                    if i = 15 then
                        state <= write_cmd;
                        i <= 0;
                    else
                        i <= i + 1;
                    end if;

                when write_cmd =>
                    rs <= '0';
                    rw <= '0';
                    en <= '1';
                    data <= cmd;
                    e <= "01";
                    state <= write_data;

                when write_data =>
                    rs <= '1';
                    rw <= '0';
                    en <= '1';
                    data <= text;
                    e <= "01";
                    state <= idle;
            end case;
        end if;
    end process;
end architecture;

这个程序实现了一个简单的状态机，用于初始化LCD1602，并向它发送指令和数据。你可以根据自己的需求修改代码，并根据需要添加其他的状态和功能。