原创 液晶lcd1602的vhdl源代码

利用FPGA驱动LCD显示中文字符"年"的VHDL程序。
--文件名        ：lcd1602.vhd。
--功能          ：   FGAD驱动LCD显示中文字符"年"。

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;
entity LCD1602 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;  
          LCD_RS : out std_logic; --寄存器选择信号
          LCD_RW : out std_logic; --液晶读写信号
          LCD_EN : out std_logic; --液晶时钟信号
    LED     : out std_logic;
          LCD_Data : out std_logic_vector(7 downto 0));   --液晶数据信号
end LCD1602;
architecture Behavioral of LCD1602 is
   type state is (set_dlnf,set_cursor,set_dcb,set_cgram,write_cgram,set_ddram,write_LCD_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;
   signal Count    : std_logic_vector(20 downto 0);
   signal Clk_Out : std_logic;
   signal LCD_Clk : std_logic;
begin
   LCD_EN <=   Clk_Out ;   --液晶时钟信号
   LED <= Clk_Out;
   LCD_RW <= '0' ;    --写数据
clock :
process(Clk,Reset)
   begin
     if(Reset = '0')then
       Count <= (others => '0');
     elsif(rising_edge(clk))then
       Count <= Count + 1;
       if(Count = 0)then
Clk_Out <= not Clk_Out;
       end if;
     end if;
     LCD_Clk <= Clk_Out;
end process;
control:
process(LCD_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');
       LCD_RS<='0';
     elsif rising_edge(LCD_Clk)then
       Current_State <= Current_State ;
       LCD_RS <= '0';
     case Current_State is
       when set_dlnf=>              
    LCD_Data<="00111100";--3cH
    Current_State<=set_cursor;
       when set_cursor=>
    LCD_Data<="00000110";--06H
    Current_State<=set_dcb;
       when set_dcb=>
    LCD_Data<="00001111";--0fH
    Current_State<=set_cgram;
       when set_cgram=>
    LCD_Data<="01000000";--40H
    Current_State<=write_cgram;
       when write_cgram=>         --向CGRAM中写入"年"
    LCD_RS<='1';
    cnt1:=cnt1+1;
    LCD_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
    LCD_Data<="10000000";--80H
    Current_State<=write_LCD_Data;
       when write_LCD_Data=>  
    LCD_RS<='1';
    LCD_Data<="00000000"; --写入字符"年"
       when others => null;
     end case;
   end if;
end process;
end Behavioral;

源自：http://hi.baidu.com/woodeasyyang/blog/item/48979cce05aacc0092457ea2.html