LiquidCrystal.cpp

// ---------------------------------------------------------------------------
// 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.cpp
// 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).
//
// The functionality provided by this class and its base class is identical
// to the original functionality of the Arduino LiquidCrystal library.
//
//
// @author F. Malpartida - fmalpartida@gmail.com
// ---------------------------------------------------------------------------
#include <stdio.h>
#include <string.h>
#include <inttypes.h>

#if (ARDUINO <  100)
#include <WProgram.h>
#else
#include <Arduino.h>
#endif
#include "LiquidCrystal.h"

// CONSTANT  definitions
// ---------------------------------------------------------------------------
#define LCD_NOBACKLIGHT 0xFF

// LCD driver configuration (4bit or 8bit driver control)
#define LCD_4BIT                1
#define LCD_8BIT                0

// STATIC helper functions
// ---------------------------------------------------------------------------


// CONSTRUCTORS
// ---------------------------------------------------------------------------

LiquidCrystal::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)
{
   init(LCD_8BIT, rs, 255, enable, d0, d1, d2, d3, d4, d5, d6, d7);
}

LiquidCrystal::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)
{
   init(LCD_8BIT, rs, rw, enable, d0, d1, d2, d3, d4, d5, d6, d7);
}

LiquidCrystal::LiquidCrystal(uint8_t rs, uint8_t rw, uint8_t enable,
                             uint8_t d0, uint8_t d1, uint8_t d2, uint8_t d3)
{
   init(LCD_4BIT, rs, rw, enable, d0, d1, d2, d3, 0, 0, 0, 0);
}

LiquidCrystal::LiquidCrystal(uint8_t rs,  uint8_t enable,
                             uint8_t d0, uint8_t d1, uint8_t d2, uint8_t d3)
{
   init(LCD_4BIT, rs, 255, enable, d0, d1, d2, d3, 0, 0, 0, 0);
}

// Contructors with backlight control
LiquidCrystal::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)
{
   init(LCD_8BIT, rs, 255, enable, d0, d1, d2, d3, d4, d5, d6, d7);
   setBacklightPin ( backlightPin, pol );
}

LiquidCrystal::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)
{
   init(LCD_8BIT, rs, rw, enable, d0, d1, d2, d3, d4, d5, d6, d7);
   setBacklightPin ( backlightPin, pol );
}

LiquidCrystal::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)
{
   init(LCD_4BIT, rs, rw, enable, d0, d1, d2, d3, 0, 0, 0, 0);
   setBacklightPin ( backlightPin, pol );
}

LiquidCrystal::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)
{
   init(LCD_4BIT, rs, 255, enable, d0, d1, d2, d3, 0, 0, 0, 0);
   setBacklightPin ( backlightPin, pol );
}

// PUBLIC METHODS
// ---------------------------------------------------------------------------

/************ low level data pushing commands **********/
//
// send
void LiquidCrystal::send(uint8_t value, uint8_t mode) 
{
   // Only interested in COMMAND or DATA
   digitalWrite( _rs_pin, ( mode == LCD_DATA ) );
   
   // if there is a RW pin indicated, set it low to Write
   // ---------------------------------------------------
   if (_rw_pin != 255) 
   { 
      digitalWrite(_rw_pin, LOW);
   }
   
   if ( mode != FOUR_BITS )
   {   
      if ( (_displayfunction & LCD_8BITMODE ) )
      {
         writeNbits(value, 8); 
      } 
      else 
      {
         writeNbits ( value >> 4, 4 );
         writeNbits ( value, 4 );
      }
   } 
   else 
   {
      writeNbits ( value, 4 );
   }
   waitUsec ( EXEC_TIME ); // wait for the command to execute by the LCD
}

//
// setBacklightPin
void LiquidCrystal::setBacklightPin ( uint8_t pin, t_backlighPol pol )
{
   pinMode ( pin, OUTPUT );       // Difine the backlight pin as output
   _backlightPin = pin;
   _polarity = pol;
   setBacklight(BACKLIGHT_OFF);   // Set the backlight low by default
}

//
// setBackligh
void LiquidCrystal::setBacklight ( uint8_t value )
{
   // Check if there is a pin assigned to the backlight
   // ---------------------------------------------------
   if ( _backlightPin != LCD_NOBACKLIGHT )
   {

      // Check if the pin is associated to a timer, i.e. PWM
      // We dont need to use != NOT_ON_TIMER hack to detect PWM and
      // 1.5x Arduino and above has a macro to check for PWM capability
      // on a pin.
      // ---------------------------------------------------
#if digitalPinHasPWM
      if(digitalPinHasPWM(_backlightPin))
#elif digitalPinToTimer
      // On older 1.x Arduino have to check using hack
      if(digitalPinToTimer(_backlightPin) != NOT_ON_TIMER)
#else
      if(0) // if neither of the above we assume no PWM
#endif
      {
         // Check for control polarity inversion
         // ---------------------------------------------------
         if ( _polarity == POSITIVE )
         {
            analogWrite ( _backlightPin, value );
         }
         else 
         {
            analogWrite ( _backlightPin, 255 - value );
         }
      }
      // Not a PWM pin, set the backlight pin for POSI or NEG
      // polarity
      // --------------------------------------------------------
      else if (((value > 0) && (_polarity == POSITIVE)) ||
               ((value == 0) && (_polarity == NEGATIVE)))
      {
         digitalWrite( _backlightPin, HIGH);
      }
      else
      {
         digitalWrite( _backlightPin, LOW);
      }
   }
}

// PRIVATE METHODS
// ---------------------------------------------------------------------------


// init
void LiquidCrystal::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)
{
   uint8_t i;
   
   // Initialize the IO pins
   // -----------------------
   
   _rs_pin = rs;
   _rw_pin = rw;
   _enable_pin = enable;
   
   _data_pins[0] = d0;
   _data_pins[1] = d1;
   _data_pins[2] = d2;
   _data_pins[3] = d3; 
   _data_pins[4] = d4;
   _data_pins[5] = d5;
   _data_pins[6] = d6;
   _data_pins[7] = d7;
   
   // Initialize the IO port direction to OUTPUT
   // ------------------------------------------
   
   for ( i = 0; i < 4; i++ )
   {
      pinMode ( _data_pins[i], OUTPUT );
   }
   
   // Initialize the rest of the ports if it is an 8bit controlled LCD
   // ----------------------------------------------------------------
   
   if ( !fourbitmode )
   {
      for ( i = 4; i < 8; i++ )
      {
         pinMode ( _data_pins[i], OUTPUT );
      }
   }
   pinMode(_rs_pin, OUTPUT);
   
   // we can save 1 pin by not using RW. Indicate by passing 255 instead of pin#
   if (_rw_pin != 255) 
   { 
      pinMode(_rw_pin, OUTPUT);
   }
   
   pinMode(_enable_pin, OUTPUT);
   
   // Initialise displaymode functions to defaults: LCD_1LINE and LCD_5x8DOTS
   // -------------------------------------------------------------------------
   if (fourbitmode)
      _displayfunction = LCD_4BITMODE | LCD_1LINE | LCD_5x8DOTS;
   else 
      _displayfunction = LCD_8BITMODE | LCD_1LINE | LCD_5x8DOTS;
   
   // Now we pull both RS and R/W low to begin commands
   digitalWrite(_rs_pin, LOW);
   digitalWrite(_enable_pin, LOW);
   
   if (_rw_pin != 255) 
   { 
      digitalWrite(_rw_pin, LOW);
   }
   
   // Initialise the backlight pin no nothing
   _backlightPin = LCD_NOBACKLIGHT;
   _polarity = POSITIVE;
}

//
// pulseEnable
void LiquidCrystal::pulseEnable(void) 
{
   // There is no need for the delays, since the digitalWrite operation
   // takes longer.
   digitalWrite(_enable_pin, HIGH);   
   waitUsec(1);          // enable pulse must be > 450ns   
   digitalWrite(_enable_pin, LOW);
}

//
// write4bits
void LiquidCrystal::writeNbits(uint8_t value, uint8_t numBits) 
{
   for (uint8_t i = 0; i < numBits; i++) 
   {
      digitalWrite(_data_pins[i], (value >> i) & 0x01);
   }
   pulseEnable();
}