text: // ---------------------------------------------------------------------------
  // Created by Francisco Malpartida on 20/08/11.
  // Copyright 2011 - Under creative commons license 3.0:
  //        Attribution-ShareAlike CC BY-SA
  //
  // This software is furnished "as is", without technical support, and with no 
  // warranty, express or implied, as to its usefulness for any purpose.
  //
  // Thread Safe: No
  // Extendable: Yes
  //
  // @file LiquidCrystal.h
  // This file implements a basic liquid crystal library that comes as standard
  // in the Arduino SDK.
  // 
  // @brief 
  // This is a basic implementation of the LiquidCrystal library of the
  // Arduino SDK. The original library has been reworked in such a way that 
  // this class implements the all methods to command an LCD based
  // on the Hitachi HD44780 and compatible chipsets using the parallel port of
  // the LCD (4 bit and 8 bit).
  //
  //
  //
  // @author F. Malpartida - fmalpartida@gmail.com
  // ---------------------------------------------------------------------------
  #ifndef LiquidCrystal_4bit_h
  #define LiquidCrystal_4bit_h
  
  #include <inttypes.h>
  
  #include "FastIO.h"
  #include "LCD.h"
  
  
  /*!
   @defined 
   @abstract   Command execution time on the LCD.
   @discussion This defines how long a command takes to execute by the LCD.
   The time is expressed in micro-seconds.
   */
  #define EXEC_TIME 37
  
  class LiquidCrystal : public LCD
  {
  public:
     /*!
      @method     
      @abstract   8 bit LCD constructors.
      @discussion Defines the pin assignment that the LCD will have.
      The constructor does not initialize the LCD.
      */
     LiquidCrystal(uint8_t rs, uint8_t enable,
                   uint8_t d0, uint8_t d1, uint8_t d2, uint8_t d3,
                   uint8_t d4, uint8_t d5, uint8_t d6, uint8_t d7);
     LiquidCrystal(uint8_t rs, uint8_t rw, uint8_t enable,
                   uint8_t d0, uint8_t d1, uint8_t d2, uint8_t d3,
                   uint8_t d4, uint8_t d5, uint8_t d6, uint8_t d7);
     
     // Constructors with backlight control
     LiquidCrystal(uint8_t rs, uint8_t enable,
                   uint8_t d0, uint8_t d1, uint8_t d2, uint8_t d3,
                   uint8_t d4, uint8_t d5, uint8_t d6, uint8_t d7,
                   uint8_t backlightPin, t_backlighPol pol);
     LiquidCrystal(uint8_t rs, uint8_t rw, uint8_t enable,
                   uint8_t d0, uint8_t d1, uint8_t d2, uint8_t d3,
                   uint8_t d4, uint8_t d5, uint8_t d6, uint8_t d7,
                   uint8_t backlightPin, t_backlighPol pol);   
     /*!
      @method     
      @abstract   4 bit LCD constructors.
      @discussion Defines the pin assignment that the LCD will have.
      The constructor does not initialize the LCD.
      */
     LiquidCrystal(uint8_t rs, uint8_t rw, uint8_t enable,
                   uint8_t d0, uint8_t d1, uint8_t d2, uint8_t d3);
     LiquidCrystal(uint8_t rs, uint8_t enable,
                   uint8_t d0, uint8_t d1, uint8_t d2, uint8_t d3);
     
     // Constructors with backlight control
     LiquidCrystal(uint8_t rs, uint8_t rw, uint8_t enable,
                   uint8_t d0, uint8_t d1, uint8_t d2, uint8_t d3,
                   uint8_t backlightPin, t_backlighPol pol);
     LiquidCrystal(uint8_t rs, uint8_t enable,
                   uint8_t d0, uint8_t d1, uint8_t d2, uint8_t d3,
                   uint8_t backlightPin, t_backlighPol pol);
     /*!
      @function
      @abstract   Send a particular value to the LCD.
      @discussion Sends a particular value to the LCD for writing to the LCD or
      as an LCD command.
      
      Users should never call this method.
      
      @param      value Value to send to the LCD.
      @result     mode LOW - write to the LCD CGRAM, HIGH - write a command to
      the LCD.
      */
     virtual void send(uint8_t value, uint8_t mode);
     
     /*!
      @function
      @abstract   Sets the pin to control the backlight.
      @discussion Sets the pin in the device to control the backlight.
      
      @param      pin: pin assigned to the backlight
      @param      pol: backlight pin control polarity (POSITIVE, NEGATIVE).
      */
     void setBacklightPin ( uint8_t pin, t_backlighPol pol );
     
     /*!
      @function
      @abstract   Switch-on/off the LCD backlight.
      @discussion Switch-on/off the LCD backlight.
      The setBacklightPin has to be called before setting the backlight for
      this method to work. @see setBacklightPin. For dimming control of the
      backlight, the configuration pin must be a PWM output pin. Dim control
      is achieved by passing a value from 1 to 255 as a parameter. If the
      pin configured when calling the setBacklightPin does not support PWM,
      then: (0) backlight off, (1..255) backlight on.
      
      @param      value: backlight value. 0: off, 1..255: dim control of the 
      backlight. For negative logic 255: off, 254..0: dim control.
      */
     void setBacklight ( uint8_t value );
     
  private:
     
     /*!
      @method     
      @abstract   Initializes the LCD pin allocation and associated HW
      @discussion Initializes the LCD pin allocation and configuration.
      */
     void init(uint8_t fourbitmode, uint8_t rs, uint8_t rw, uint8_t enable,
               uint8_t d0, uint8_t d1, uint8_t d2, uint8_t d3,
               uint8_t d4, uint8_t d5, uint8_t d6, uint8_t d7);
     
     /*!
      @method     
      @abstract   Writes numBits bits from value value to the LCD.
      @discussion Writes numBists bits (the least significant) to the LCD control 
      data lines.
      */   
     void writeNbits(uint8_t value, uint8_t numBits);
     
     /*!
      @method     
      @abstract   Pulse the LCD enable line (En).
      @discussion Sends a pulse of 1 uS to the Enable pin to execute an command
      or write operation.
      */ 
     void pulseEnable();
     
     uint8_t _rs_pin;       // LOW: command.  HIGH: character.
     uint8_t _rw_pin;       // LOW: write to LCD.  HIGH: read from LCD.
     uint8_t _enable_pin;   // activated by a HIGH pulse.
     uint8_t _data_pins[8]; // Data pins.
     uint8_t _backlightPin; // Pin associated to control the LCD backlight
  };
  
  #endif
  