LiquidCrystal.cpp

#include "LiquidCrystal.h"
#include <inttypes.h>
#include <Arduino.h>
#include <Wire.h>

// When the display powers up, it is configured as follows:
//
// 1. Display clear
// 2. Function set: 
//    DL = 1; 8-bit interface data 
//    N = 0; 1-line display 
//    F = 0; 5x8 dot character font 
// 3. Display on/off control: 
//    D = 0; Display off 
//    C = 0; Cursor off 
//    B = 0; Blinking off 
// 4. Entry mode set: 
//    I/D = 1; Increment by 1 
//    S = 0; No shift 
//
// Note, however, that resetting the Arduino doesn't reset the LCD, so we
// can't assume that its in that state when a sketch starts (and the
// LiquidCrystal constructor is called).

void LiquidCrystal::begin() {
  #if defined(__AVR_ATmega1284P__) || defined(__AVR_ATmega1284__)
  if (_type == LCD_I2C) {
	  _displayfunction = LCD_4BITMODE | LCD_2LINE | LCD_5x8DOTS;

	  // SEE PAGE 45/46 FOR INITIALIZATION SPECIFICATION!
	  // according to datasheet, we need at least 40ms after power rises above 2.7V
	  // before sending commands. Arduino can turn on way befer 4.5V so we'll wait 50
	  delay(50); 

	  // Now we pull both RS and R/W low to begin commands
	  expanderWrite(_backlightval);	// reset expanderand turn backlight off (Bit 8 =1)
	  delay(1000);

	  //put the LCD into 4 bit mode
	  // this is according to the hitachi HD44780 datasheet
	  // figure 24, pg 46

	  // we start in 8bit mode, try to set 4 bit mode
	  write4bits(0x03 << 4);
	  delayMicroseconds(4500); // wait min 4.1ms

	  // second try
	  write4bits(0x03 << 4);
	  delayMicroseconds(4500); // wait min 4.1ms

	  // third go!
	  write4bits(0x03 << 4); 
	  delayMicroseconds(150);

	  // finally, set to 4-bit interface
	  write4bits(0x02 << 4); 

	  // set # lines, font size, etc.
	  command(LCD_FUNCTIONSET | _displayfunction);  
	
	  // turn the display on with no cursor or blinking default
	  _displaycontrol = LCD_DISPLAYON | LCD_CURSOROFF | LCD_BLINKOFF;
	  display();
	
	  // clear it off
	  clear();
	
	  // Initialize to default text direction (for roman languages)
	  _displaymode = LCD_ENTRYLEFT | LCD_ENTRYSHIFTDECREMENT;
	
	  // set the entry mode
	  command(LCD_ENTRYMODESET | _displaymode);
	
	  home();
	}
	#endif
	
  if (_type == LCD_STD) {	
    _displayfunction |= LCD_2LINE;
    _numlines = 2;
    _currline = 0;

    // SEE PAGE 45/46 FOR INITIALIZATION SPECIFICATION!
    // according to datasheet, we need at least 40ms after power rises above 2.7V
    // before sending commands. Arduino can turn on way befer 4.5V so we'll wait 50
    delayMicroseconds(50000); 
    // 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);
    }
    
    //put the LCD into 4 bit or 8 bit mode
    if (! (_displayfunction & LCD_8BITMODE)) {
      // this is according to the hitachi HD44780 datasheet
      // figure 24, pg 46

      // we start in 8bit mode, try to set 4 bit mode
      write4bits(0x03);
      delayMicroseconds(4500); // wait min 4.1ms

      // second try
      write4bits(0x03);
      delayMicroseconds(4500); // wait min 4.1ms
      
      // third go!
      write4bits(0x03); 
      delayMicroseconds(150);

      // finally, set to 4-bit interface
      write4bits(0x02); 
    } else {
      // this is according to the hitachi HD44780 datasheet
      // page 45 figure 23

      // Send function set command sequence
      command(LCD_FUNCTIONSET | _displayfunction);
      delayMicroseconds(4500);  // wait more than 4.1ms

      // second try
      command(LCD_FUNCTIONSET | _displayfunction);
      delayMicroseconds(150);

      // third go
      command(LCD_FUNCTIONSET | _displayfunction);
    }

    // finally, set # lines, font size, etc.
    command(LCD_FUNCTIONSET | _displayfunction);  

    // turn the display on with no cursor or blinking default
    _displaycontrol = LCD_DISPLAYON | LCD_CURSOROFF | LCD_BLINKOFF;  
    display();

    // clear it off
    clear();

    // Initialize to default text direction (for romance languages)
    _displaymode = LCD_ENTRYLEFT | LCD_ENTRYSHIFTDECREMENT;
    // set the entry mode
    command(LCD_ENTRYMODESET | _displaymode);
  }
}

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)
{
  _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; 
  
	Wire.begin();
  _type = LCD_STD;
  #if defined(__AVR_ATmega1284P__) || defined(__AVR_ATmega1284__)
  // detect I2C and assign _type variable accordingly
  Wire.beginTransmission(LCD_I2C_ADDR);
  Wire.write(0x00);
  uint8_t ret = Wire.endTransmission();
  if (!ret)  _type = LCD_I2C;  
  
  if (_type == LCD_I2C) {
	  _addr = LCD_I2C_ADDR;
	  _cols = 16;
	  _rows = 2;
	  _charsize = LCD_5x8DOTS;
	  _backlightval = LCD_BACKLIGHT;
	}	  
  #endif

  if (_type == LCD_STD) {
    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);
    
  }
  _displayfunction = LCD_4BITMODE | LCD_2LINE | LCD_5x8DOTS;

}

/********** high level commands, for the user! */
void LiquidCrystal::clear()
{
  command(LCD_CLEARDISPLAY);// clear display, set cursor position to zero
  delayMicroseconds(2000);  // this command takes a long time!
}

void LiquidCrystal::home()
{
  command(LCD_RETURNHOME);  // set cursor position to zero
  delayMicroseconds(2000);  // this command takes a long time!
}

void LiquidCrystal::setCursor(uint8_t col, uint8_t row)
{
  int row_offsets[] = { 0x00, 0x40, 0x14, 0x54 };
  #if defined(__AVR_ATmega1284P__) || defined(__AVR_ATmega1284__)  
  if (_type == LCD_I2C) {
    if (row > _rows) {
      row = _rows-1;    // we count rows starting w/0
    }
  }
  #endif
  if (_type == LCD_STD) {
    if (row >= _numlines) {
      row = _numlines-1;
    }
  }  
  command(LCD_SETDDRAMADDR | (col + row_offsets[row]));
}

// Turn the display on/off (quickly)
void LiquidCrystal::noDisplay() {
  _displaycontrol &= ~LCD_DISPLAYON;
  command(LCD_DISPLAYCONTROL | _displaycontrol);
}
void LiquidCrystal::display() {
  _displaycontrol |= LCD_DISPLAYON;
  command(LCD_DISPLAYCONTROL | _displaycontrol);
}

// Turns the underline cursor on/off
void LiquidCrystal::noCursor() {
  _displaycontrol &= ~LCD_CURSORON;
  command(LCD_DISPLAYCONTROL | _displaycontrol);
}
void LiquidCrystal::cursor() {
  _displaycontrol |= LCD_CURSORON;
  command(LCD_DISPLAYCONTROL | _displaycontrol);
}

// Turn on and off the blinking cursor
void LiquidCrystal::noBlink() {
  _displaycontrol &= ~LCD_BLINKON;
  command(LCD_DISPLAYCONTROL | _displaycontrol);
}
void LiquidCrystal::blink() {
  _displaycontrol |= LCD_BLINKON;
  command(LCD_DISPLAYCONTROL | _displaycontrol);
}

// These commands scroll the display without changing the RAM
void LiquidCrystal::scrollDisplayLeft(void) {
  command(LCD_CURSORSHIFT | LCD_DISPLAYMOVE | LCD_MOVELEFT);
}
void LiquidCrystal::scrollDisplayRight(void) {
  command(LCD_CURSORSHIFT | LCD_DISPLAYMOVE | LCD_MOVERIGHT);
}

// This is for text that flows Left to Right
void LiquidCrystal::leftToRight(void) {
  _displaymode |= LCD_ENTRYLEFT;
  command(LCD_ENTRYMODESET | _displaymode);
}

// This is for text that flows Right to Left
void LiquidCrystal::rightToLeft(void) {
  _displaymode &= ~LCD_ENTRYLEFT;
  command(LCD_ENTRYMODESET | _displaymode);
}

// This will 'right justify' text from the cursor
void LiquidCrystal::autoscroll(void) {
  _displaymode |= LCD_ENTRYSHIFTINCREMENT;
  command(LCD_ENTRYMODESET | _displaymode);
}

// This will 'left justify' text from the cursor
void LiquidCrystal::noAutoscroll(void) {
  _displaymode &= ~LCD_ENTRYSHIFTINCREMENT;
  command(LCD_ENTRYMODESET | _displaymode);
}

// Allows us to fill the first 8 CGRAM locations
// with custom characters
void LiquidCrystal::createChar(uint8_t location, uint8_t charmap[]) {
  location &= 0x7; // we only have 8 locations 0-7
  command(LCD_SETCGRAMADDR | (location << 3));
  for (int i=0; i<8; i++) {
    write(charmap[i]);
  }
}

#if defined(__AVR_ATmega1284P__) || defined(__AVR_ATmega1284__)
// Turn the (optional) backlight off/on
void LiquidCrystal::noBacklight(void) {
  _backlightval=LCD_NOBACKLIGHT;
  expanderWrite(0);
}

void LiquidCrystal::backlight(void) {
  _backlightval=LCD_BACKLIGHT;
  expanderWrite(0);
}
#endif

/*********** mid level commands, for sending data/cmds */

inline void LiquidCrystal::command(uint8_t value) {
	send(value, 0);
}

inline size_t LiquidCrystal::write(uint8_t value) {
	send(value, Rs);
  return 1; // assume sucess
}

/************ low level data pushing commands **********/

// write either command or data
void LiquidCrystal::send(uint8_t value, uint8_t mode) {
  #if defined(__AVR_ATmega1284P__) || defined(__AVR_ATmega1284__)
  if (_type == LCD_I2C) {
	  uint8_t highnib=value&0xf0;
	  uint8_t lownib=(value<<4)&0xf0;
	  write4bits((highnib)|mode);
	  write4bits((lownib)|mode); 
  } 
  #endif
  if (_type == LCD_STD) {
    digitalWrite(_rs_pin, mode);

    // if there is a RW pin indicated, set it low to Write
    if (_rw_pin != 255) { 
      digitalWrite(_rw_pin, LOW);
    }
    
    write4bits(value>>4);
    write4bits(value);
  }
}

void LiquidCrystal::write4bits(uint8_t value) {
  #if defined(__AVR_ATmega1284P__) || defined(__AVR_ATmega1284__)
  if (_type == LCD_I2C) {
	  expanderWrite(value);
	  pulseEnable(value);
  }
  #endif
  if (_type == LCD_STD) {
    for (int i = 0; i < 4; i++) {
      pinMode(_data_pins[i], OUTPUT);
      digitalWrite(_data_pins[i], (value >> i) & 0x01);
    }

    pulseEnable();
  }
}

#if defined(__AVR_ATmega1284P__) || defined(__AVR_ATmega1284__)
void LiquidCrystal::expanderWrite(uint8_t _data){                                        
	Wire.beginTransmission(_addr);
	Wire.write((int)(_data) | _backlightval);
	Wire.endTransmission();   
}

void LiquidCrystal::pulseEnable(uint8_t _data){
	expanderWrite(_data | En);	// En high
	delayMicroseconds(1);		// enable pulse must be >450ns
	
	expanderWrite(_data & ~En);	// En low
	delayMicroseconds(50);		// commands need > 37us to settle
}
#endif

void LiquidCrystal::pulseEnable(void) {
  digitalWrite(_enable_pin, LOW);
  delayMicroseconds(1);    
  digitalWrite(_enable_pin, HIGH);
  delayMicroseconds(1);    // enable pulse must be >450ns
  digitalWrite(_enable_pin, LOW);
  delayMicroseconds(100);   // commands need > 37us to settle
}