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LiquidCrystal.cpp
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LiquidCrystal.cpp
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// ---------------------------------------------------------------------------
// 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();
}