------------------------------------------------------------------------------------ Company: -- Engineer: -- -- Create Date:    21:39:44 12/03/2007 -- Design Name: -- Module Name:    PS2 - Behavioral -- Project Name: -- Target Devices: -- Tool versions: -- Description: ---- Dependencies: ---- Revision: -- Revision 0.01 - File Created-- Additional Comments: ------------------------------------------------------------------------------------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 PS2 is    Port ( dclk : in  STD_LOGIC;           datain : in  STD_LOGIC;			  lcd_e : out  STD_LOGIC;           lcd_rw : out  STD_LOGIC;           lcd_rs : out  STD_LOGIC;           sf_d : out  STD_LOGIC_VECTOR (3 downto 0);           clk : in  STD_LOGIC);end PS2;architecture Behavioral of PS2 issignal count : integer range 0 to 10 :=0;signal lword1,lword2 : std_logic_vector(3 downto 0);signal hword1,hword2 : std_logic_vector(3 downto 0);signal state : integer range 0 to 7 := 0;Type data is array (0 to 3, 0 to 1) of std_logic_vector(3 downto 0);constant cmd : data := (("0010","1000"),--Function set								  ("0000","0110"),--Entry mode set								  ("0000","1100"),--Display on/off								  ("1000","0000")--Set DDram address								  );signal index : integer range 0 to 4 :=0;signal count0 : integer range 0 to 750000 := 0;signal sflag : std_logic := '0';signal flag : integer range 0 to 15 := 0;signal twochar: std_logic :='0';beginprocess(clk)beginif rising_edge(clk) then	if(state = 0) then --initializtion		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 <= 1;				lcd_rs <= '0';				lcd_rw <= '0';				sf_d <= cmd(index,0);--the high 4bits			else				count0 <= count0+1;			end if;						end if;			elsif state = 1 then	--send command		if flag = 0 then	   --delay 40ns			if count0 = 2 then				flag <= 1;				count0 <= 0;				lcd_e <= '1';   			else				count0 <= count0+1;			end if;		elsif flag = 1 then  --delay 230ns			if count0 = 12 then				flag <= 2;				lcd_e <= '0';				count0 <= 0;			else				count0 <= count0+1;			end if;		elsif flag = 2 then --delay 20ns			if count0 = 1 then				if sflag = '0' then --the word is not finished										flag <= 3;				else					flag <= 4; 				end if;				lcd_rw <= '1';				count0 <= 0;							else				count0 <= count0+1;			end if;		elsif flag = 3 then --delay 1us,low 4bits			if count0 = 50 then				sflag <= '1';				flag <= 0;				lcd_rw <= '0';				count0 <= 0;				sf_d <= cmd(index,1);				index <= index+1;			else				count0 <= count0+1;			end if;		elsif flag = 4 then --delay 40us, the word is finished			if count0 = 2000 then				sflag <= '0';				flag <= 0;				lcd_rw <= '0';				count0 <= 0;				if index = 4 then					lcd_rs <= '1';					state <= 2;				else					sf_d <= cmd(index,0);				end if;			else				count0 <= count0+1;			end if;		end if;			elsif state = 2 then --read data		if dclk = '0' then --transfer start			if twochar = '0' then --character								if count=9 then --parity check 					case hword1&lword1 is						when "00011100"=>hword1<="0110";lword1<="0001";--a
						when "00110010"=>hword1<="0110";lword1<="0010";--b
						when "00100001"=>hword1<="0110";lword1<="0011";--c
						when "00100011"=>hword1<="0110";lword1<="0100";--d
						when "00100100"=>hword1<="0110";lword1<="0101";--e
						when "00101011"=>hword1<="0110";lword1<="0110";--f
						when "00110100"=>hword1<="0110";lword1<="0111";--g						when others=>hword1<="1111";lword1<="0000";					end case;
					state <= 3;					elsif count=11 then --transfer finished					sf_d <= hword1;					twochar <= '1';					count <= 0;
					state <= 3;					elsif (count>0 and count<5) then--low 4bits					lword1(count-1) <= datain;
					state <= 3;					elsif (count>4 and count<9) then --high 4bits					hword1(count-5) <= datain;
					state <= 3;	
				else
					state <= 3;					end if;				else  				if count=11 then					if ( lword2="0000" and hword2="1111") then						twochar <= '0';						state <= 4;
					else
						state <= 3;						end if;					count <= 0;									elsif (count>0 and count<5) then					lword2(count-1) <= datain;
					state <= 3;					elsif (count>4 and count<9) then --high 4bits					hword2(count-5) <= datain;
					state <= 3;	
				else 
					state <= 3;					end if;			end if;					end if;		elsif state = 3 then --read next bit			if count0 = 4000 then --delay 80us				count <= count+1;				state <= 2;				count0 <= 0;			else				count0 <= count0+1;			end if;				elsif state = 4 then --send characters		if flag = 0 then	   --delay 40ns			if count0 = 2 then				flag <= 1;				count0 <= 0;				lcd_e <= '1';			else				count0 <= count0+1;			end if;		elsif flag = 1 then  --delay 230ns			if count0 = 12 then				flag <= 2;				lcd_e <= '0';				count0 <= 0;			else				count0 <= count0+1;				end if;		elsif flag = 2 then --delay 20ns			if count0 = 1 then				if sflag = '0' then --the word is not finished									flag <= 3;				else					flag <= 4; 				end if;				lcd_rw <= '1';				count0 <= 0;							else				count0 <= count0+1;			end if;		elsif flag = 3 then --delay 1us,low 4bits			if count0 = 50 then				sflag <= '1';				flag <= 0;				lcd_rw <= '0';				count0 <= 0;				sf_d <= lword1 ;			else				count0 <= count0+1;			end if;		elsif flag = 4 then --delay 40us			if count0 = 2000 then				sflag <= '0';				flag <= 0;				lcd_rw <= '0';				state <= 2;				count0 <= 0;			else				count0 <= count0+1;			end if;		end if;			end if;	end if;end process;end Behavioral;