HD44780 LCD Probleme - Altera DE2-115

------------------------------------------------------------------- 

--                        ASCII HEX TABLE

--  Hex            Low Hex Digit

-- Value  0   1   2   3   4   5   6   7   8   9   A   B   C   D   E   F

------\----------------------------------------------------------------

--H  2 |  SP  !   "   #   $   %   &   '   (   )   *   +   ,   -   .   /

--i  3 |  0   1   2   3   4   5   6   7   8   9   :   ;   <   =   >   ?

--g  4 |  @   A   B   C   D   E   F   G   H   I   J   K   L   M   N   O

--h  5 |  P   Q   R   S   T   U   V   W   X   Y   Z   [   \   ]   ^   _

--   6 |  `   a   b   c   d   e   f   g   h   i   j   k   l   m   n   o

--   7 |  p   q   r   s   t   u   v   w   x   y   z   {   |   }   ~ DEL

-----------------------------------------------------------------------

LIBRARY IEEE;

USE  IEEE.STD_LOGIC_1164.all;

USE  IEEE.STD_LOGIC_ARITH.all;

USE  IEEE.STD_LOGIC_UNSIGNED.all;

entity lcd_control is

  port

  (

    trigger,trigger2, clk     : in  std_logic;

    ascii                     : in  std_logic_vector(7 downto 0);

    lcd_rs, lcd_e, lcd_rw      : out  std_logic;

    lcd_data                 : out std_logic_vector(7 downto 0);

    lcd_an                : out std_logic

    );

end lcd_control;

architecture behv of lcd_control is

type state_type is ( START, START_WAIT, FUNC_SET_WAIT, DISP_ON_WAIT,

                    DROP_E, HOLD,

                    FUNC_SET, DISP_ON, DISP_CLEAR, MODE_SET,

                    WAIT_CHAR, DISP_CLEAR_WAIT,

                    WAIT_TRIGGER_RESET,

                    CHK_CNT, LINE2, HOME);

signal state, next_command : state_type;

signal char_cnt : std_logic_vector(5 downto 0);

signal wait_cnt : std_logic_vector(7 downto 0);

begin

   process(clk)      

  begin

  if trigger2='1' then      -- a switch to turn the lcd on and off

  lcd_an<='1';  

  lcd_rw<='0';           -- setting the rw permenantly to 1

   else  

  lcd_an<='0';

  end if;

  state <= START;

    case state is

      when START =>       

        lcd_e <= '1';

        lcd_rs <= '0';

        lcd_data <= X"38";                 -- set the lcd to 8 bit lenght

        wait_cnt<=X"00";

        state <= DROP_E;                   -- function of DROP_E: just sets lcd_e to '1' and state goes to next_command      

        next_command <= START_WAIT;

        when START_WAIT =>                 -- waiting for a few msec 

         if wait_cnt < X"10" then       

          wait_cnt <= wait_cnt +1;

          state <= START_WAIT;

        else

          state <= FUNC_SET;            

          wait_cnt <= X"00";          

        end if;

      when FUNC_SET =>

        lcd_e <= '1';

        lcd_rs <= '0';

        lcd_data <= X"38";

        state <= DROP_E;            

        next_command <= FUNC_SET_WAIT;

        when FUNC_SET_WAIT =>

         if wait_cnt < X"10" then         

          wait_cnt <= wait_cnt +1;

          state <= FUNC_SET_WAIT;

        else

          state <= DISP_ON;            

          wait_cnt <= X"00";          

        end if;

      when DISP_ON =>

        lcd_e <= '1';

        lcd_rs <= '0';

        lcd_data <= X"0F";                   -- set the lcd to Display on, Cursor is displayed, Blinking enable, 

        state <= DROP_E;            

        next_command <= DISP_ON_WAIT;

        when DISP_ON_WAIT =>

         if wait_cnt < X"10" then    

          wait_cnt <= wait_cnt +1;

          state <= DISP_ON_WAIT;

        else

          state <= DISP_CLEAR;        

          wait_cnt <= X"00";          

        end if;

      when DISP_CLEAR =>

        lcd_e <= '1';

        lcd_rs <= '0';

        lcd_data <= X"01";                -- command: clear the display 

        wait_cnt <= X"00";

        state <= DROP_E;            

        next_command <= DISP_CLEAR_WAIT;

      when DISP_CLEAR_WAIT =>

         if wait_cnt < X"10" then    

          wait_cnt <= wait_cnt +1;

          state <= DISP_CLEAR_WAIT;

        else

          state <= MODE_SET;            

          wait_cnt <= X"00";          

        end if;

      when MODE_SET =>

        lcd_e <= '1';

        lcd_rs <= '0';

        lcd_data <= X"06";               -- Cursor moves right, Display shift enabled.

        state <= DROP_E;

        next_command <= WAIT_CHAR;

---------------- initialization done, Loop of writing begins -------------------------------------------

--   WAIT_CHAR -> DROP_E -> HOLD -> WAIT_TRIGGER_RESET -> CHK_CNT -> LINE2 -> DROP_E -> HOLD -> |

--                                                                |                              |

--        ^                                                       -> HOME  -> DROP_E -> HOLD -> |

--        |                                                       |                              |

--        |                                                       v                             v

--        |----------------------------------------<<-------------------------------------------|

-------------------------------------------------------------------------------------------------

      when WAIT_CHAR =>

        if trigger = '0' then               -- trigger is set to a switch

          lcd_e <= '1';

          lcd_rs <= '1';

          lcd_data <= ascii;                -- ascii is defined through 7 switchs

          char_cnt <= char_cnt +1;          -- a counter for the written letters

          state <= DROP_E;

          next_command <= WAIT_TRIGGER_RESET;

        else

          next_command <= WAIT_CHAR;

        end if;

      when WAIT_TRIGGER_RESET =>              -- loop, waiting for an change at the switch

        if trigger = '0' then

           state <= WAIT_TRIGGER_RESET;

        else

          state <= CHK_CNT;

        end if;

      when CHK_CNT =>                         -- checking if the first line is full of letters, 

        if char_cnt = X"10" then

          state <= LINE2;                

        elsif char_cnt = X"20" then

          state <= HOME;                     -- clears the display 

        else

          state <= WAIT_CHAR;

        end if;

      when LINE2 =>                            -- starts writing at the secound line

        lcd_e <= '1';

        lcd_rs <= '0';

        lcd_data <= X"C0";                    -- sets the DDRAM-Adress to '1000000'

        state <= DROP_E;

        next_command <= WAIT_CHAR;

      when HOME =>

         lcd_e <= '1';

        lcd_rs <= '0';

        lcd_data <= X"80";                    -- sets the DDRAM-adress to '0000000'

        char_cnt <= "000000";

        state <= DROP_E;

        next_command <= WAIT_CHAR;

      when DROP_E =>      

        lcd_e <= '1';

        state <= HOLD;

      when HOLD =>

        state <= next_command;

    end case;

  end process;

end behv;