--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;