--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;