lcddisplay.vhd

Xilinx sparten3E Lcd显示程序

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-- Company: 
-- Engineer: 
-- 
-- Create Date:    18:30:12 11/26/2007 
-- Design Name: 
-- Module Name:    Lcddisplay - Behavioral 
-- Project Name: 
-- Target Devices: 
-- Tool versions: 
-- Description: 
--
-- Dependencies: 
--
-- Revision: 
-- Revision 0.01 - File Created
-- Additional Comments: 
--
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library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;

---- Uncomment the following library declaration if instantiating
---- any Xilinx primitives in this code.
--library UNISIM;
--use UNISIM.VComponents.all;

entity Lcddisplay is
    Port ( lcd_e : inout  STD_LOGIC;
           lcd_rw : inout  STD_LOGIC;
           lcd_rs : inout  STD_LOGIC;
           sf_d : inout  STD_LOGIC_VECTOR (3 downto 0);
			  clk : in STD_LOGIC);
end Lcddisplay;

architecture Behavioral of Lcddisplay is
signal state : std_logic_vector(1 downto 0) := "00";
Type data is array (0 to 7, 0 to 1) of std_logic_vector(3 downto 0);
constant words : data := (("0010","1000"),--Function set
								  ("0000","0110"),--Entry mode set
								  ("0000","1100"),--Display on/off
								  ("1000","0000"),--Set DDram address
								  ("0100","0110"),--F
								  ("0101","0000"),--P
								  ("0100","0111"),--G
								  ("0100","0001") --A
								  );
signal index : integer range 0 to 8 :=0;
signal count0 : integer range 0 to 750000 := 0;
signal sflag : std_logic := '0';
signal flag : integer range 0 to 15 := 0;
begin

process(clk)
begin
if rising_edge(clk) then
	if(state = "00") then --初始化 
		if(flag = 0) then
			if count0 = 750000 then
				flag <= 1;
				sf_d <= "0011";
				lcd_e <= '1';
				count0 <= 0;
			else
				count0 <= count0+1;
			end if;
		elsif flag = 1 then
			if count0 = 12 then
				flag <= 2;
				lcd_e <= '0';
				count0 <= 0;
			else
				count0 <= count0+1;
			end if;
		elsif flag = 2 then
			if count0 = 205000 then
				flag <= 3;
				sf_d <= "0011";
				lcd_e <= '1';
				count0 <= 0;
			else
				count0 <= count0+1;
			end if;
		elsif flag = 3 then
			if count0 = 12 then
				flag <= 4;
				lcd_e <= '0';
				count0 <= 0;
			else
				count0 <= count0+1;
			end if;
		elsif flag = 4 then
			if count0 = 5000 then
				flag <= 5;
				sf_d <= "0011";
				lcd_e <= '1';
				count0 <= 0;
			else
				count0 <= count0+1;
			end if;	
		elsif flag = 5 then
			if count0 = 12 then
				flag <= 6;
				lcd_e <= '0';
				count0 <= 0;
			else
				count0 <= count0+1;
			end if;	
		elsif flag = 6 then
			if count0 = 2000 then
				flag <= 7;
				sf_d <= "0010";
				lcd_e <= '1';
				count0 <= 0;
			else
				count0 <= count0+1;
			end if;	
		elsif flag = 7 then
			if count0 = 12 then
				flag <= 8;
				lcd_e <= '0';
				count0 <= 0;
			else
				count0 <= count0+1;
			end if;	
		else
			if count0 = 2000 then
				flag <= 0;
				count0 <= 0;
				state <= "01";
				lcd_rs <= '0';
				lcd_rw <= '0';
				sf_d <= words(index,0);
			else
				count0 <= count0+1;
			end if;				
		end if;
		
	elsif state = "01" then	--配置显示
		if flag = 0 then	   --延时40ns
			if count0 = 2 then
				flag <= 1;
				count0 <= 0;
				lcd_e <= '1';
			else
				count0 <= count0+1;
			end if;
		elsif flag = 1 then  --延时230ns
			if count0 = 12 then
				flag <= 2;
				lcd_e <= '0';
				count0 <= 0;
			else
				count0 <= count0+1;
				end if;
		elsif flag = 2 then --延时20ns
			if count0 = 1 then
				if sflag = '0' then --一个字节未完					
					flag <= 3;
				else
					flag <= 4; --next 4bits			
				end if;
				lcd_rw <= '1';
				count0 <= 0;
			else
				count0 <= count0+1;
			end if;
		elsif flag = 3 then --延时1us
			if count0 = 50 then
				sflag <= '1';
				flag <= 0;
				lcd_rw <= '0';
				count0 <= 0;
				sf_d <= words(index,1);
				index <= index+1;
			else
				count0 <= count0+1;
			end if;
		elsif flag = 4 then --延时40us
			if count0 = 2000 then
				sflag <= '0';
				flag <= 0;
				lcd_rw <= '0';
				count0 <= 0;
				sf_d <= words(index,0);
				if index = 4 then
					lcd_rs <= '1';
				end if;
				if index = 8 then
					state <= "10";
				end if;
			else
				count0 <= count0+1;
			end if;
		end if;
	else
	end if;
	
	

end if;--clk
end process;

end Behavioral;