lcd显示.txt

本程序是用VHDL语言编写液晶驱动程序,实现在液晶上显示"年"字的功能.

--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;