lcd_schnittstelle.vhd

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--

--   FileName:         lcd_example.vhd

--   Dependencies:     none

--   Design Software:  Quartus II 32-bit Version 11.1 Build 173 SJ Full Version

--

--   HDL CODE IS PROVIDED "AS IS."  DIGI-KEY EXPRESSLY DISCLAIMS ANY

--   WARRANTY OF ANY KIND, WHETHER EXPRESS OR IMPLIED, INCLUDING BUT NOT

--   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A

--   PARTICULAR PURPOSE, OR NON-INFRINGEMENT. IN NO EVENT SHALL DIGI-KEY

--   BE LIABLE FOR ANY INCIDENTAL, SPECIAL, INDIRECT OR CONSEQUENTIAL

--   DAMAGES, LOST PROFITS OR LOST DATA, HARM TO YOUR EQUIPMENT, COST OF

--   PROCUREMENT OF SUBSTITUTE GOODS, TECHNOLOGY OR SERVICES, ANY CLAIMS

--   BY THIRD PARTIES (INCLUDING BUT NOT LIMITED TO ANY DEFENSE THEREOF),

--   ANY CLAIMS FOR INDEMNITY OR CONTRIBUTION, OR OTHER SIMILAR COSTS.

--

--   Version History

--   Version 1.0 6/13/2012 Scott Larson

--     Initial Public Release

--

--   Prints "123456789" on a HD44780 compatible 8-bit interface character LCD 

--   module using the lcd_controller.vhd component.

--

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LIBRARY ieee;

USE ieee.std_logic_1164.all;

ENTITY lcd_schnittstelle IS

  PORT(

      clk       : IN  STD_LOGIC;  --system clock

      rw, rs, e : OUT STD_LOGIC;  --read/write, setup/data, and enable for lcd

      lcd_data  : OUT STD_LOGIC_VECTOR(7 DOWNTO 0)); --data signals for lcd

END lcd_schnittstelle;

ARCHITECTURE behavior OF lcd_schnittstelle IS

  SIGNAL   lcd_enable : STD_LOGIC;

  SIGNAL   lcd_bus    : STD_LOGIC_VECTOR(9 DOWNTO 0);

  SIGNAL   lcd_busy   : STD_LOGIC;

  COMPONENT lcd_controller IS

    PORT(

       clk        : IN  STD_LOGIC; --system clock

       reset_n    : IN  STD_LOGIC; --active low reinitializes lcd

       lcd_enable : IN  STD_LOGIC; --latches data into lcd controller

       lcd_bus    : IN  STD_LOGIC_VECTOR(9 DOWNTO 0); --data and control signals

       busy       : OUT STD_LOGIC; --lcd controller busy/idle feedback

       rw, rs, e  : OUT STD_LOGIC; --read/write, setup/data, and enable for lcd

       lcd_data   : OUT STD_LOGIC_VECTOR(7 DOWNTO 0)); --data signals for lcd

  END COMPONENT;

BEGIN

  --instantiate the lcd controller

  dut: lcd_controller

    PORT MAP(clk => clk, reset_n => '1', lcd_enable => lcd_enable, lcd_bus => lcd_bus, 

             busy => lcd_busy, rw => rw, rs => rs, e => e, lcd_data => lcd_data);

  PROCESS(clk)

    VARIABLE char  :  INTEGER RANGE 0 TO 10 := 0;

  BEGIN

    IF(clk'EVENT AND clk = '1') THEN

      IF(lcd_busy = '0' AND lcd_enable = '0') THEN

        lcd_enable <= '1';

        IF(char < 10) THEN

          char := char + 1;

        END IF;

        CASE char IS

          WHEN 1 => lcd_bus <= "1000110001";

          WHEN 2 => lcd_bus <= "1000110010";

          WHEN 3 => lcd_bus <= "1000110011";

          WHEN 4 => lcd_bus <= "1000110100";

          WHEN 5 => lcd_bus <= "1000110101";

          WHEN 6 => lcd_bus <= "1000110110";

          WHEN 7 => lcd_bus <= "1000110111";

          WHEN 8 => lcd_bus <= "1000111000";

          WHEN 9 => lcd_bus <= "1000111001";

          WHEN OTHERS => lcd_enable <= '0';

        END CASE;

      ELSE

        lcd_enable <= '0';

      END IF;

    END IF;

  END PROCESS;

END behavior;