LCD控制VHDL程序与仿真
1. FPGA驱动LCD显示中文字符“年”程序
--文件名：lcd_driver.vhd。
--功能：FGAD驱动LCD显示中文字符“年”。
--最后修改日期：2004.3.24。
library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;
entity lcd_driver is
    Port ( clk : in std_logic; --状态机时钟信号，同时也是液晶时钟信号，其周期应该满足液晶数据的建立时间
      reset:in std_logic;
         lcdda : out std_logic;         --寄存器选择信号
         lcdrw : out std_logic;      --液晶读写信号
         lcden : out std_logic;      --液晶时钟信号
         data : out std_logic_vector(7 downto 0));  --液晶数据信号
end lcd_driver;

architecture Behavioral of lcd_driver is
type state is (set_dlnf,set_cursor,set_dcb,set _cgram,write _cgram,set_ddram,write_data);
    signal current_state:state;
    type ram2 is array(0 to 7) of std_logic_vector(7 downto 0);
constant cgram:ram2:=(("00001000"),("00001111"),("00010010"),
("00001111"),("00001010"),("00011111"),("00000010"),("00000010"));--年字符数据存储器                          
    signal clkk : std_logic;
begin

    lcden <=  clk ; --液晶时钟信号
lcdrw <= '0' ;  --写数据

    control:process(clk,reset,current_state)               --液晶驱动控制器
          variable cnt1: std_logic_vector(2 downto 0);
     begin
   if reset='0'then
         current_state<=set_dlnf;
      cnt1:=(others => '1');
      lcdda<='0';
       elsif rising_edge(clk)then
      current_state <= current_state ;
      lcdda <= '0';
      case current_state is
       when set_dlnf=>              
        data<="00111100";--3cH
        current_state<=set_cursor;
               when set_cursor=>
        data<="00000110";--06H
        current_state<=set_dcb;
               when set_dcb=>
        data<="00001111";--0fH
        current_state<=set_ cgram;
      when set_ cgram=>
        data<="01000000";--40H
        current_state<=write_ cgram;
      when write_ cgram=> --向CGRAM中写入“年”
        lcdda<='1';
        cnt1:=cnt1+1;
        data<=cgram(conv_integer(cnt1));       
        if cnt1 = "111" then
       current_state<=set_ddram;        
        end if;
     when set_ddram=>     --从第一行的起始地址开始显示
        data<="10000000";--80H
        current_state<=write_data;
              when write_data=>   
        lcdda<='1';
        data<="00000000"; --写入字符“年”
     when others => null;
    end case;
    end if;
          end process;
end Behavioral;