library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;

entity display is

port (clk_400 : in std_ulogic; --400Hz Taktsignal
sys_clk : in std_ulogic; --Systemtakt 50Mhz
reset : in std_ulogic; --Reset-Signal
data_input : in std_ulogic_vector (13 downto 0); --Token-Signal des Morsedecoders
enable_char : in std_ulogic; --Pausen-Signal der Entity morsedecoder ob ein Token-Signal abgeschlossen ist
vga_next : in std_ulogic; --Schalter zum Ändern der Zeile bei Videoausgabe
vga_clear : in std_ulogic; --Taste zum vollständigen Löschen des gesamten Bildschirm Push-button[1]/KEY[1]
del_switch : in std_ulogic; --Schalter zum Aktivieren der Löschfunktion mittels Morsetaste
data_out : out std_ulogic_vector (7 downto 0); --Datensignale für das LCD (Zeichen)
lcd_control : out std_ulogic_vector (3 DOWNTO 0); --Steuersignale für das LCD
rx_done_tick: out std_ulogic; --Zeichenausgabe-Signal (VGA)
vga_out : out std_ulogic_vector (7 downto 0)); --Datensignale für den Bildschirm (Hex)

end display;

 

architecture structure of display is


signal LCD_DATA : std_ulogic_vector (7 downto 0); --Datensignal für das Display
signal LCD_ON, LCD_RS, LCD_EN, LCD_RW : std_ulogic; --Steuersignale für das Display

signal sig_old : std_ulogic; --Signale zum Prüfen eines Signalwechsels
signal sig_rise : std_ulogic;

 

--Signale für die VGA-Steuerung
signal rx_done_tick_sig :std_ulogic;
signal vga_out_sig : std_ulogic_vector (7 downto 0);
signal lcd_en_fall : std_ulogic;
signal lcd_en_old : std_ulogic;
signal en_old : std_ulogic;
signal en_fall : std_ulogic;
signal valid : std_ulogic := '0';
signal state: natural range 0 to 25;
signal state2: natural range 0 to 6;
signal state3: natural range 0 to 3;
signal cnt : natural;
signal del : std_ulogic := '0';

begin

 

vga_control: process (sys_clk, reset, LCD_DATA, LCD_EN, LCD_RS, vga_next, lcd_en_old, lcd_en_fall, valid, state, state2, state3, en_old, en_fall)

begin

if reset = '0' then
   rx_done_tick_sig <= '0';
   vga_out_sig <= (others => '0');
   lcd_en_fall <= '0';
   en_old <= '0';
   en_fall <= '0';
   state <= 0;
   state2 <= 0;
   state3 <= 0;
   cnt <= 0;
elsif sys_clk'event and sys_clk ='1' then
   lcd_en_old <= LCD_EN;
   en_old <= vga_next;
   cnt <= cnt + 1;
   if en_old ='1' and vga_next = '0' then
      en_fall <='1';
      rx_done_tick_sig <= '0';
   else
      en_fall <='0';
   end if;
   if lcd_en_old ='1' and LCD_EN = '0' then -- Die eingegebenen Zeichen können nur übertragen werden, wenn LCD_EN = '0'
      lcd_en_fall <= '1';
      else
      lcd_en_fall <= '0';
   end if;

   if (en_fall ='1' or state > 0 ) and valid = '1' then
      case state is
         when 0=>
             vga_out_sig <= x"5A"; --ENTER
             rx_done_tick_sig <= '1';
             state <= state +1;
          when 1=>
             rx_done_tick_sig <= '0';
             state <= state +1;
          when 2=>
             vga_out_sig <= x"4D"; --"M"
             rx_done_tick_sig <= '1';
             state <= state +1;
          when 3=>
             rx_done_tick_sig <= '0';
             state <= state +1;
          when 4=>
             vga_out_sig <= x"4F"; --"O"
             rx_done_tick_sig <= '1';
             state <= state +1;
          when 5=>
             rx_done_tick_sig <= '0';
             state <= state +1;
          when 6=>
             vga_out_sig <= x"52"; --"R"
             rx_done_tick_sig <= '1';
             state <= state +1;
          when 7=>
             rx_done_tick_sig <= '0';
             state <= state +1;
          when 8=>
             vga_out_sig <= x"53"; --"S"
             rx_done_tick_sig <= '1';
             state <= state +1;
          when 9=>
             rx_done_tick_sig <= '0';
             state <= state +1;
          when 10=>
             vga_out_sig <= x"45"; --"E"
             rx_done_tick_sig <= '1';
             state <= state +1;
          when 11=>
             rx_done_tick_sig <= '0';
             state <= state +1;
          when 12=>
             vga_out_sig <= x"43"; --"C"
             rx_done_tick_sig <= '1';
             state <= state +1;
          when 13=>
             rx_done_tick_sig <= '0';
             state <= state +1;
          when 14=>
             vga_out_sig <= x"4F"; --"O"
             rx_done_tick_sig <= '1';
             state <= state +1;
          when 15=>
             rx_done_tick_sig <= '0';
             state <= state +1;
          when 16=>
             vga_out_sig <= x"44"; --"D"
             rx_done_tick_sig <= '1';
             state <= state +1;
          when 17=>
             rx_done_tick_sig <= '0';
             state <= state +1;
          when 18=>
             vga_out_sig <= x"45"; --"E"
             rx_done_tick_sig <= '1';
             state <= state +1;
          when 19=>
             rx_done_tick_sig <= '0';
             state <= state +1;
          when 20=>
             vga_out_sig <= x"20"; --"Leer"
             rx_done_tick_sig <= '1';
             state <= state +1;
          when 21=>
             rx_done_tick_sig <= '0';
             state <= state +1;
          when 22=>
             vga_out_sig <= x"1A"; --">"
             rx_done_tick_sig <= '1';
             state <= state +1;
          when 23=>
             rx_done_tick_sig <= '0';
             state <= state +1;
          when 24 =>
             en_fall <='0';
             state <= 25;
          when others =>
             state <= 0;
       end case;

   elsif (cnt >= (10*10**6) and del_switch = '1') and (sig_rise = '1' or state2 > 0) then
      del <= not del;
      cnt <= 0;
      case state2 is
         when 0=>
             vga_out_sig <= x"6B"; --Cursor springt nach links
             rx_done_tick_sig <= '1';
             state2 <= state2 +1;
          when 1=>
             rx_done_tick_sig <= '0';
             state2 <= state2 +1;
          when 2=>
             vga_out_sig <= x"20"; --Leerzeichen "Löschen"
             rx_done_tick_sig <= '1';
             state2 <= state2 +1;
          when 3=>
             rx_done_tick_sig <= '0';
             state2 <= state2 +1;
          when 4=>
             vga_out_sig <= x"6B"; --Cursor springt nach links
             rx_done_tick_sig <= '1';
             state2 <= state2 +1;
          when 5=>
             rx_done_tick_sig <= '0';
             state2 <= state2 +1;
          when others =>
             state2 <= 0;
      end case;

   elsif vga_clear = '0' then
      case state3 is
           when 0=>
             vga_out_sig <= x"66"; --Backspace "Clear All"
             rx_done_tick_sig <= '1';
             state3 <= state3 +1;
           when 1=>
             rx_done_tick_sig <= '0';
             state3 <= state3 +1;
           when others =>
             state3 <= 0;
      end case;

  elsif valid = '0' then
     rx_done_tick_sig <='0';
  elsif lcd_en_fall = '1' then
     vga_out_sig <= LCD_DATA;
     rx_done_tick_sig <='1';
     lcd_en_fall <= '0';
  else
     rx_done_tick_sig <='0';
  end if;

  rx_done_tick <= rx_done_tick_sig;
  vga_out <= vga_out_sig;

end if;

end process;
--------------------------------------------------------------
--Ansteuerung des Displays mit Initialisierung und Ausgabe der Zeichnen--
--------------------------------------------------------------
LCD_init: process (clk_400, reset, data_input, enable_char, valid)

variable ini : natural range 0 to 11 := 0;
variable next_command : natural range 0 to 11 := 0;
variable char_cnt : natural range 0 to 34 := 0;
variable char : integer range 0 tO 12 := 0;
begin

--LCD reinitialisieren

if reset = '0' then
LCD_ON <= '1'; --LCD Power ON/OFF
LCD_EN <= '1'; --LCD Aktivierung
LCD_RW <= '0'; --LCD Schreiben(0)/Lesen(1)
LCD_RS <= '0'; --LCD Kommando(0)/Daten(1)
LCD_DATA <= x"38"; --Display aus / Beide Zeilen leer (=reset)
valid <= '0';

ini := 0;
next_command := 0;
char_cnt := 0;

elsif clk_400'event and clk_400 = '1' then

case ini is

--LCD Initialisierung

when 0 =>

LCD_ON <= '1';
LCD_EN <= '1';
LCD_RW <= '0';
LCD_RS <= '0';
LCD_DATA <= x"38"; --Display aus / Beide Zeilen leer (=reset)
valid <= '0';

next_command := next_command+1;
ini := 8;

when 1 =>

LCD_ON <= '1';
LCD_EN <= '1';
LCD_RW <= '0';
LCD_RS <= '0';
LCD_DATA <= x"38"; --Display aus / Beide Zeilen leer (=reset)
next_command := next_command+1;
ini := 8;

when 2 =>

LCD_ON <= '1';
LCD_EN <= '1';
LCD_RW <= '0';
LCD_RS <= '0';
LCD_DATA <= x"38"; --Display aus / Beide Zeilen leer (=reset)
next_command := next_command+1;
ini := 8;

when 3 =>

LCD_ON <= '1';
LCD_EN <= '1';
LCD_RW <= '0';
LCD_RS <= '0';
LCD_DATA <= x"38"; --Display aus / Beide Zeilen leer (=reset) 4x notwendig zum Initialisieren
next_command := next_command+1;
ini := 8;

when 4 =>

LCD_ON <= '1';
LCD_EN <= '1';
LCD_RW <= '0';
LCD_RS <= '0';
LCD_DATA <= x"0D"; --Display ein / Cursor blinkt an Position
next_command := next_command+1;
ini := 8;

when 5 =>

LCD_ON <= '1';
LCD_EN <= '1';
LCD_RW <= '0';
LCD_RS <= '0';
LCD_DATA <= x"01"; --Display leeren
next_command := next_command+1;
ini := 8;

when 6 =>

LCD_ON <= '1';
LCD_EN <= '1';
LCD_RW <= '0';
LCD_RS <= '0';
LCD_DATA <= x"0D"; --Display ein / Cursor blinkt an Position
next_command := next_command+1;
ini := 8;

when 7 =>

LCD_ON <= '1';
LCD_EN <= '1';
LCD_RW <= '0';
LCD_RS <= '0';
LCD_DATA <= x"06"; --Addresse wird automatisch inkrementiert und der Cursor nach rechts verschoben
valid <= '0';

next_command := 11;
ini := 8;

-- Initialisierung ist ab hier beendet

 

when 8 =>

--Dieser Zyklus dient dazu das Enable-Signal in LCD_EN auch auf '0' zu setzen.
--Ansonsten können die Daten nicht an den Bildschirm übertragen werden!!!
LCD_ON <= '1';
LCD_EN <= '0';
ini := next_command;

when 9 =>
LCD_ON <= '1';
LCD_EN <= '1';
LCD_RW <= '0';
LCD_RS <= '1';
LCD_DATA <= x"20"; --" "
next_command:= 10;
ini := 8;

when 10 =>
LCD_ON <= '1';
LCD_EN <= '1';
LCD_RW <= '0';
LCD_RS <= '0';
LCD_DATA <= x"10"; --scrollt cursor nach links
next_command := 11;
ini := 8;

when 11 =>

if char_cnt = 16 then

LCD_RS <= '0';
LCD_EN <= '1';
LCD_RW <= '0';
LCD_ON <= '1';

LCD_DATA <= x"C0"; --Setzt den Cursor an den Anfang der zweiten Zeile des Displays
char_cnt := char_cnt + 1;
ini := 8;

elsif char_cnt = 34 then

LCD_ON <= '1';
LCD_EN <= '1';
LCD_RW <= '0';
LCD_RS <= '0';

LCD_DATA <= x"01"; --Display leeren
char_cnt := 0;
ini := 8;

 

else

valid <= '1';

sig_rise <= '0'; --Das Signal "sig_rise" wird standardmäßig auf ein LOW gesetzt, da dass enable_char-Signal nicht immer eine steigende Flanke hat
sig_old <= enable_char; --Das aktuelle enable_char-Signal wird "sig_old" zugewiesen

 

if sig_old = '0' AND enable_char = '1' then --Überprüfung ob sich Signale unterscheiden, ist dies der Fall (positive Flanke)
sig_rise <= '1';
--Die Zuweisung erfolgt erst im nächsten Taktzyklus, deshalb ist die vorherige Zuweisung zu prüfen
end if;

 

----------------------------------------
--Ansteuerung des LCD im Decoder-Modus--
----------------------------------------
If sig_rise = '1' then
LCD_ON <= '1';
LCD_EN <= '1';
LCD_RW <= '0';
LCD_RS <= '1';

case data_input is

when "00000000000000" => LCD_EN <= '0';

--Buchstaben
when "00000000000111" => LCD_DATA <=x"41"; -- A
when "00000011010101" => LCD_DATA <=x"42"; -- B
when "00000011011101" => LCD_DATA <=x"43"; -- C
when "00000000110101" => LCD_DATA <=x"44"; -- D
when "00000000000001" => LCD_DATA <=x"45"; -- E
when "00000001011101" => LCD_DATA <=x"46"; -- F
when "00000000111101" => LCD_DATA <=x"47"; -- G
when "00000001010101" => LCD_DATA <=x"48"; -- H
when "00000000000101" => LCD_DATA <=x"49"; -- I
when "00000001111111" => LCD_DATA <=x"4A"; -- J
when "00000000110111" => LCD_DATA <=x"4B"; -- K
when "00000001110101" => LCD_DATA <=x"4C"; -- L
when "00000000001111" => LCD_DATA <=x"4D"; -- M
when "00000000001101" => LCD_DATA <=x"4E"; -- N
when "00000000111111" => LCD_DATA <=x"4F"; -- O
when "00000001111101" => LCD_DATA <=x"50"; -- P
when "00000011110111" => LCD_DATA <=x"51"; -- Q
when "00000000011101" => LCD_DATA <=x"52"; -- R
when "00000000010101" => LCD_DATA <=x"53"; -- S
when "00000000000011" => LCD_DATA <=x"54"; -- T
when "00000000010111" => LCD_DATA <=x"55"; -- U
when "00000001010111" => LCD_DATA <=x"56"; -- V
when "00000000011111" => LCD_DATA <=x"57"; -- W
when "00000011010111" => LCD_DATA <=x"58"; -- X
when "00000011011111" => LCD_DATA <=x"59"; -- Y
when "00000011110101" => LCD_DATA <=x"5A"; -- Z

--Zahlen
when "00001111111111" => LCD_DATA <=x"30"; -- 0
when "00000111111111" => LCD_DATA <=x"31"; -- 1
when "00000101111111" => LCD_DATA <=x"32"; -- 2
when "00000101011111" => LCD_DATA <=x"33"; -- 3
when "00000101010111" => LCD_DATA <=x"34"; -- 4
when "00000101010101" => LCD_DATA <=x"35"; -- 5
when "00001101010101" => LCD_DATA <=x"36"; -- 6
when "00001111010101" => LCD_DATA <=x"37"; -- 7
when "00001111110101" => LCD_DATA <=x"38"; -- 8
when "00001111111101" => LCD_DATA <=x"39"; -- 9

 

when others => LCD_DATA <= x"3F";

end case;
char_cnt := char_cnt + 1;
ini := 8;

 

if del_switch = '1' and char_cnt = 0 then
next_command := 5;
elsif del_switch = '1' and char_cnt > 0 then
LCD_RS <= '0';
LCD_DATA <= x"10";
valid <= '0';
next_command := 9;
char_cnt := char_cnt - 2;
end if;

 

end if;

end if;

end case;

--Übertragung der Steuersignale und Datenbits an das LCD

lcd_control(3) <= LCD_ON;
lcd_control(0) <= LCD_EN;
lcd_control(1) <= LCD_RW;
lcd_control(2) <= LCD_RS;

data_out <= LCD_DATA;

end if;

end process;

end structure;