LiquidCrystal_I2C.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_I2C.c
// This file implements a basic liquid crystal library that comes as standard
// in the Arduino SDK but using an I2C IO extension board.
// 
// @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 I2C extension
// backpacks such as the I2CLCDextraIO with the PCF8574* I2C IO Expander ASIC.
//
// 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 <inttypes.h>
#include "I2CIO.h"
#include "LiquidCrystal_I2C.h"

// CONSTANT  definitions
// ---------------------------------------------------------------------------

// flags for backlight control
/*!
 @defined 
 @abstract   LCD_NOBACKLIGHT
 @discussion NO BACKLIGHT MASK
 */
#define LCD_NOBACKLIGHT 0x00

/*!
 @defined 
 @abstract   LCD_BACKLIGHT
 @discussion BACKLIGHT MASK used when backlight is on
 */
#define LCD_BACKLIGHT   0xFF


// Default library configuration parameters used by class constructor with
// only the I2C address field.
// ---------------------------------------------------------------------------
/*!
 @defined 
 @abstract   Enable bit of the LCD
 @discussion Defines the IO of the expander connected to the LCD Enable
 */
#define EN 6  // Enable bit

/*!
 @defined 
 @abstract   Read/Write bit of the LCD
 @discussion Defines the IO of the expander connected to the LCD Rw pin
 */
#define RW 5  // Read/Write bit

/*!
 @defined 
 @abstract   Register bit of the LCD
 @discussion Defines the IO of the expander connected to the LCD Register select pin
 */
#define RS 4  // Register select bit

/*!
 @defined 
 @abstract   LCD dataline allocation this library only supports 4 bit LCD control
 mode.
 @discussion D4, D5, D6, D7 LCD data lines pin mapping of the extender module
 */
#define D4 0
#define D5 1
#define D6 2
#define D7 3


// CONSTRUCTORS
// ---------------------------------------------------------------------------
LiquidCrystal_I2C::LiquidCrystal_I2C(const char *dev, uint8_t lcd_Addr)
{
   config(dev, lcd_Addr, EN, RW, RS, D4, D5, D6, D7);
}


LiquidCrystal_I2C::LiquidCrystal_I2C(const char *dev, uint8_t lcd_Addr, uint8_t backlighPin, t_backlighPol pol = POSITIVE)
{
   config(dev, lcd_Addr, EN, RW, RS, D4, D5, D6, D7);
   setBacklightPin(backlighPin, pol);
}

LiquidCrystal_I2C::LiquidCrystal_I2C(const char *dev, uint8_t lcd_Addr, uint8_t En, uint8_t Rw,
                                     uint8_t Rs)
{
   config(dev, lcd_Addr, En, Rw, Rs, D4, D5, D6, D7);
}

LiquidCrystal_I2C::LiquidCrystal_I2C(const char *dev, uint8_t lcd_Addr, uint8_t En, uint8_t Rw,
                                     uint8_t Rs, uint8_t backlighPin, 
                                     t_backlighPol pol = POSITIVE)
{
   config(dev, lcd_Addr, En, Rw, Rs, D4, D5, D6, D7);
   setBacklightPin(backlighPin, pol);
}

LiquidCrystal_I2C::LiquidCrystal_I2C(const char *dev, uint8_t lcd_Addr, uint8_t En, uint8_t Rw,
                                     uint8_t Rs, uint8_t d4, uint8_t d5,
                                     uint8_t d6, uint8_t d7 )
{
   config(dev, lcd_Addr, En, Rw, Rs, d4, d5, d6, d7);
}

LiquidCrystal_I2C::LiquidCrystal_I2C(const char *dev, uint8_t lcd_Addr, uint8_t En, uint8_t Rw,
                                     uint8_t Rs, uint8_t d4, uint8_t d5,
                                     uint8_t d6, uint8_t d7, uint8_t backlighPin, 
                                     t_backlighPol pol = POSITIVE )
{
   config(dev, lcd_Addr, En, Rw, Rs, d4, d5, d6, d7);
   setBacklightPin(backlighPin, pol);
}

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

//
// begin
void LiquidCrystal_I2C::begin(uint8_t cols, uint8_t lines, uint8_t dotsize) 
{
   
   init();     // Initialise the I2C expander interface
   LCD::begin ( cols, lines, dotsize );   
}


// User commands - users can expand this section
//----------------------------------------------------------------------------
// Turn the (optional) backlight off/on

//
// setBacklightPin
void LiquidCrystal_I2C::setBacklightPin ( uint8_t value, t_backlighPol pol = POSITIVE )
{
   _backlightPinMask = ( 1 << value );
   _polarity = pol;
   setBacklight(BACKLIGHT_OFF);
}

//
// setBacklight
void LiquidCrystal_I2C::setBacklight( uint8_t value ) 
{
   // Check if backlight is available
   // ----------------------------------------------------
   if ( _backlightPinMask != 0x0 )
   {
      // Check for polarity to configure mask accordingly
      // ----------------------------------------------------------
      if  (((_polarity == POSITIVE) && (value > 0)) || 
           ((_polarity == NEGATIVE ) && ( value == 0 )))
      {
         _backlightStsMask = _backlightPinMask & LCD_BACKLIGHT;
      }
      else 
      {
         _backlightStsMask = _backlightPinMask & LCD_NOBACKLIGHT;
      }
      _i2cio.write( _backlightStsMask );
   }
}


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

//
// init
int LiquidCrystal_I2C::init()
{
   int status = 0;
   
   // initialize the backpack IO expander
   // and display functions.
   // ------------------------------------------------------------------------
   if ( _i2cio.begin ( _dev, _Addr ) == 1 )
   {
      _i2cio.portMode ( OUTPUT );  // Set the entire IO extender to OUTPUT
      _displayfunction = LCD_4BITMODE | LCD_1LINE | LCD_5x8DOTS;
      status = 1;
      _i2cio.write(0);  // Set the entire port to LOW
   }
   return ( status );
}

//
// config
void LiquidCrystal_I2C::config (const char *dev, uint8_t lcd_Addr, uint8_t En, uint8_t Rw, uint8_t Rs, 
                                uint8_t d4, uint8_t d5, uint8_t d6, uint8_t d7 )
{
   _Addr = lcd_Addr;
   _dev = dev;
   
   _backlightPinMask = 0;
   _backlightStsMask = LCD_NOBACKLIGHT;
   _polarity = POSITIVE;
   
   _En = ( 1 << En );
   _Rw = ( 1 << Rw );
   _Rs = ( 1 << Rs );
   
   // Initialise pin mapping
   _data_pins[0] = ( 1 << d4 );
   _data_pins[1] = ( 1 << d5 );
   _data_pins[2] = ( 1 << d6 );
   _data_pins[3] = ( 1 << d7 );
}



// low level data pushing commands
//----------------------------------------------------------------------------

//
// send - write either command or data
void LiquidCrystal_I2C::send(uint8_t value, uint8_t mode) 
{
   // No need to use the delay routines since the time taken to write takes
   // longer that what is needed both for toggling and enable pin an to execute
   // the command.
   
   if ( mode == FOUR_BITS )
   {
      write4bits( (value & 0x0F), COMMAND );
   }
   else 
   {
      write4bits( (value >> 4), mode );
      write4bits( (value & 0x0F), mode);
   }
}

//
// write4bits
void LiquidCrystal_I2C::write4bits ( uint8_t value, uint8_t mode ) 
{
   uint8_t pinMapValue = 0;
   
   // Map the value to LCD pin mapping
   // --------------------------------
   for ( uint8_t i = 0; i < 4; i++ )
   {
      if ( ( value & 0x1 ) == 1 )
      {
         pinMapValue |= _data_pins[i];
      }
      value = ( value >> 1 );
   }
   
   // Is it a command or data
   // -----------------------
   if ( mode == DATA )
   {
      mode = _Rs;
   }
   
   pinMapValue |= mode | _backlightStsMask;
   pulseEnable ( pinMapValue );
}

//
// pulseEnable
void LiquidCrystal_I2C::pulseEnable (uint8_t data)
{
   _i2cio.write (data | _En);   // En HIGH
   _i2cio.write (data & ~_En);  // En LOW
}