LCD控制VHDL程序與仿真
1. FPGA驅動LCD顯示中文字符“年”程序
--文件名：lcd_driver.vhd。
--功能：FGAD驅動LCD顯示中文字符“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;?--狀態機時鐘信號，同時也是液晶時鐘信號，其周期應該滿足液晶數據的建立時間
????? reset:in std_logic;
???????? lcdda : out std_logic;???????? --寄存器選擇信號
???????? lcdrw : out std_logic;??????--液晶讀寫信號
???????? lcden : out std_logic;??????--液晶時鐘信號
???????? data : out std_logic_vector(7 downto 0));??--液晶數據信號
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"));--年字符數據存儲器??????????????????????????
??? signal clkk : std_logic;
begin

??? lcden <=? clk ; --液晶時鐘信號
lcdrw <= '0' ;? --寫數據

??? control:process(clk,reset,current_state)?????????????? --液晶驅動控制器
????????? 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中寫入“年”
??????? lcdda<='1';
??????? cnt1:=cnt1+1;
??????? data<=cgram(conv_integer(cnt1));???????
??????? if cnt1 = "111" then
?????? current_state<=set_ddram;?????? ?
??????? end if;
???? when set_ddram=>???? --從第一行的起始地址開始顯示
??????? data<="10000000";--80H
??????? current_state<=write_data;
????????????? when write_data=>???
??????? lcdda<='1';
??????? data<="00000000"; --寫入字符“年”
???? when others => null;
????end case;
??? end if;
????????? end process;
end Behavioral;