File content as of revision 3:3468dc87d641:

//Header //

// commands
#define LCD_CLEARDISPLAY 0x01
#define LCD_RETURNHOME   0x02
#define LCD_ENTRYMODESET 0x04
#define LCD_DISPLAYCONTROL 0x08
#define LCD_CURSORSHIFT  0x10
#define LCD_FUNCTIONSET  0x20
#define LCD_SETCGRAMADDR 0x40
#define LCD_SETDDRAMADDR 0x80

// flags for display entry mode
#define LCD_ENTRYRIGHT 0x00
#define LCD_ENTRYLEFT 0x02
#define LCD_ENTRYSHIFTINCREMENT 0x01
#define LCD_ENTRYSHIFTDECREMENT 0x00

// flags for display on/off control
#define LCD_DISPLAYON 0x04
#define LCD_DISPLAYOFF 0x00
#define LCD_CURSORON 0x02
#define LCD_CURSOROFF 0x00
#define LCD_BLINKON 0x01
#define LCD_BLINKOFF 0x00

// flags for display/cursor shift
#define LCD_DISPLAYMOVE 0x08
#define LCD_CURSORMOVE 0x00
#define LCD_MOVERIGHT 0x04
#define LCD_MOVELEFT 0x00

// flags for function set
#define LCD_8BITMODE 0x10
#define LCD_4BITMODE 0x00
#define LCD_2LINE 0x08
#define LCD_1LINE 0x00
#define LCD_5x10DOTS 0x04
#define LCD_5x8DOTS 0x00

// flags for backlight control
#define LCD_BACKLIGHT 0x08
#define LCD_NOBACKLIGHT 0x00

#define En 4 //B00000100  // Enable bit
#define Rw 2 //B00000010  // Read/Write bit
#define Rs 1 //B00000001  // Register select bit

//public 

  void LiquidCrystal_I2Cbegin(uint8_t cols, uint8_t rows, uint8_t charsize = LCD_5x8DOTS );
  void LCDI2C4Bit_clear();
  void LiquidCrystal_I2Cclear();
  void LiquidCrystal_I2Chome();
  void LiquidCrystal_I2CnoDisplay();
  void LiquidCrystal_I2Cdisplay();
  void LiquidCrystal_I2CnoBlink();
  void LiquidCrystal_I2Cblink();
  void LiquidCrystal_I2CnoCursor();
  void LiquidCrystal_I2Ccursor();
  void LiquidCrystal_I2CscrollDisplayLeft();
  void LiquidCrystal_I2CscrollDisplayRight();
  void LiquidCrystal_I2CprintLeft();
  void LiquidCrystal_I2CprintRight();
  void LiquidCrystal_I2CleftToRight();
  void LiquidCrystal_I2CrightToLeft();
  void LiquidCrystal_I2CshiftIncrement();
  void LiquidCrystal_I2CshiftDecrement();
  void LiquidCrystal_I2CnoBacklight();
  void LiquidCrystal_I2Cbacklight();
  void LiquidCrystal_I2Cautoscroll();
  void LiquidCrystal_I2CnoAutoscroll(); 
  void LiquidCrystal_I2CcreateChar(uint8_t, uint8_t[]);
  void LiquidCrystal_I2CsetCursor(uint8_t, uint8_t); 
  void LiquidCrystal_I2Cwrite(uint8_t);
  void LiquidCrystal_I2Ccommand(uint8_t);
  void LiquidCrystal_I2Cinit();

//private
  void init_priv();
  void send(uint8_t, uint8_t);
  void write4bits(uint8_t);
  void expanderWrite(uint8_t);
  void pulseEnable(uint8_t);

//YWROBOT
//last updated on 21/12/2011
//Tim Starling Fix the reset bug (Thanks Tim)
//wiki doc http://www.dfrobot.com/wiki/index.php?title=I2C/TWI_LCD1602_Module_(SKU:_DFR0063)
//Support Forum: http://www.dfrobot.com/forum/
//Compatible with the Arduino IDE 1.0
//Library version:1.1

I2C Wire(PTC11, PTC10); //SDA , SCL

// 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).






  uint8_t _Addr;
  uint8_t _displayfunction;
  uint8_t _displaycontrol;
  uint8_t _displaymode;
  uint8_t _numlines;
  uint8_t _cols;
  uint8_t _rows;
  uint8_t _backlightval;


void delay(int msec)
{
   wait_ms(msec); 
} 
   
void delayMicroseconds(int microsec)
{
  wait_us(microsec);      
}    

void LCDI2C4Bit_clear()
{
  LiquidCrystal_I2Cclear();
}

void LiquidCrystal_I2C_SETUP(uint8_t lcd_Addr,uint8_t lcd_cols,uint8_t lcd_rows)
{
  _Addr = lcd_Addr;
  _cols = lcd_cols;
  _rows = lcd_rows;
  _backlightval = LCD_NOBACKLIGHT;
}




void LiquidCrystal_I2Cinit(){
    init_priv();
    
}




void init_priv()
{
   // Wire.begin();
    _displayfunction = LCD_4BITMODE | LCD_1LINE | LCD_5x8DOTS;
    LiquidCrystal_I2Cbegin(_cols, _rows); 
    
     
}

void LiquidCrystal_I2Cbegin(uint8_t cols, uint8_t lines, uint8_t dotsize) {
    if (lines > 1) {
        _displayfunction |= LCD_2LINE;
    }
    _numlines = lines;

    // for some 1 line displays you can select a 10 pixel high font
    if ((dotsize != 0) && (lines == 1)) {
        _displayfunction |= LCD_5x10DOTS;
    }

    // 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.
    LiquidCrystal_I2Ccommand(LCD_FUNCTIONSET | _displayfunction);  
    
    // turn the display on with no cursor or blinking default
    _displaycontrol = LCD_DISPLAYON | LCD_CURSOROFF | LCD_BLINKOFF;
    LiquidCrystal_I2Cdisplay();
    
    // clear it off
    LiquidCrystal_I2Cclear();
    
    // Initialize to default text direction (for roman languages)
    _displaymode = LCD_ENTRYLEFT | LCD_ENTRYSHIFTDECREMENT;
    
    // set the entry mode
    LiquidCrystal_I2Ccommand(LCD_ENTRYMODESET | _displaymode);
    
    LiquidCrystal_I2Chome();
  
}

/********** high level commands, for the user! */
void LiquidCrystal_I2Cclear(){
    LiquidCrystal_I2Ccommand(LCD_CLEARDISPLAY);// clear display, set cursor position to zero
    delayMicroseconds(2000);  // this command takes a long time!
}

void LiquidCrystal_I2Chome(){
    LiquidCrystal_I2Ccommand(LCD_RETURNHOME);  // set cursor position to zero
    delayMicroseconds(2000);  // this command takes a long time!
}

void LiquidCrystal_I2CsetCursor(uint8_t col, uint8_t row){
    int row_offsets[] = { 0x00, 0x40, 0x14, 0x54 };
    if ( row > _numlines ) {
        row = _numlines-1;    // we count rows starting w/0
    }
    LiquidCrystal_I2Ccommand(LCD_SETDDRAMADDR | (col + row_offsets[row]));
}

 void LCDI2C4Bit_cursorTo(uint8_t col, uint8_t row)
 {
    if (col==2) col=1;
    LiquidCrystal_I2CsetCursor(row,col); 
}     

// Turn the display on/off (quickly)
void LiquidCrystal_I2CnoDisplay() {
    _displaycontrol &= ~LCD_DISPLAYON;
    LiquidCrystal_I2Ccommand(LCD_DISPLAYCONTROL | _displaycontrol);
}
void LiquidCrystal_I2Cdisplay() {
    _displaycontrol |= LCD_DISPLAYON;
    LiquidCrystal_I2Ccommand(LCD_DISPLAYCONTROL | _displaycontrol);
}

// Turns the underline cursor on/off
void LiquidCrystal_I2CnoCursor() {
    _displaycontrol &= ~LCD_CURSORON;
    LiquidCrystal_I2Ccommand(LCD_DISPLAYCONTROL | _displaycontrol);
}
void LiquidCrystal_I2Ccursor() {
    _displaycontrol |= LCD_CURSORON;
    LiquidCrystal_I2Ccommand(LCD_DISPLAYCONTROL | _displaycontrol);
}

// Turn on and off the blinking cursor
void LiquidCrystal_I2CnoBlink() {
    _displaycontrol &= ~LCD_BLINKON;
    LiquidCrystal_I2Ccommand(LCD_DISPLAYCONTROL | _displaycontrol);
}
void LiquidCrystal_I2Cblink() {
    _displaycontrol |= LCD_BLINKON;
    LiquidCrystal_I2Ccommand(LCD_DISPLAYCONTROL | _displaycontrol);
}

// These commands scroll the display without changing the RAM
void LiquidCrystal_I2CscrollDisplayLeft(void) {
    LiquidCrystal_I2Ccommand(LCD_CURSORSHIFT | LCD_DISPLAYMOVE | LCD_MOVELEFT);
}
void LiquidCrystal_I2CscrollDisplayRight(void) {
    LiquidCrystal_I2Ccommand(LCD_CURSORSHIFT | LCD_DISPLAYMOVE | LCD_MOVERIGHT);
}

// This is for text that flows Left to Right
void LiquidCrystal_I2CleftToRight(void) {
    _displaymode |= LCD_ENTRYLEFT;
    LiquidCrystal_I2Ccommand(LCD_ENTRYMODESET | _displaymode);
}

// This is for text that flows Right to Left
void LiquidCrystal_I2CrightToLeft(void) {
    _displaymode &= ~LCD_ENTRYLEFT;
    LiquidCrystal_I2Ccommand(LCD_ENTRYMODESET | _displaymode);
}

// This will 'right justify' text from the cursor
void LiquidCrystal_I2Cautoscroll(void) {
    _displaymode |= LCD_ENTRYSHIFTINCREMENT;
    LiquidCrystal_I2Ccommand(LCD_ENTRYMODESET | _displaymode);
}

// This will 'left justify' text from the cursor
void LiquidCrystal_I2CnoAutoscroll(void) {
    _displaymode &= ~LCD_ENTRYSHIFTINCREMENT;
    LiquidCrystal_I2Ccommand(LCD_ENTRYMODESET | _displaymode);
}

// Allows us to fill the first 8 CGRAM locations
// with custom characters
void LiquidCrystal_I2CcreateChar(uint8_t location, uint8_t charmap[]) {
    location &= 0x7; // we only have 8 locations 0-7
    LiquidCrystal_I2Ccommand(LCD_SETCGRAMADDR | (location << 3));
    for (int i=0; i<8; i++) {
        //write(charmap[i]);
        send(charmap[i], Rs);
    }
}

// Turn the (optional) backlight off/on
void LiquidCrystal_I2CnoBacklight(void) {
    _backlightval=LCD_NOBACKLIGHT;
    expanderWrite(0);
}

void LiquidCrystal_I2Cbacklight(void) {
    _backlightval=LCD_BACKLIGHT;
    expanderWrite(0);
}



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

inline void LiquidCrystal_I2Ccommand(uint8_t value) {
    send(value, 0);
}


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

// write either command or data
void send(uint8_t value, uint8_t mode) {
    uint8_t highnib=value&0xf0;
    uint8_t lownib=(value<<4)&0xf0;
    write4bits((highnib)|mode);
    write4bits((lownib)|mode); 
}

void write4bits(uint8_t value) {
    expanderWrite(value);
    pulseEnable(value);
}

void expanderWrite(uint8_t _data)
{     

/*                                   
    Wire.beginTransmission(_Addr);
    printIIC((int)(_data) | _backlightval);
    Wire.endTransmission();   
    
    */
  char data[2]; 
  data[0]= _data | _backlightval;
 // data[1]=val;
  char result=Wire.write(_Addr<<1,data,1);     
    
}

void 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
} 


// Alias functions

void LiquidCrystal_I2Ccursor_on(){
    LiquidCrystal_I2Ccursor();
}

void LiquidCrystal_I2Ccursor_off(){
    LiquidCrystal_I2CnoCursor();
}

void LiquidCrystal_I2Cblink_on(){
    LiquidCrystal_I2Cblink();
}

void LiquidCrystal_I2Cblink_off(){
    LiquidCrystal_I2CnoBlink();
}

void LiquidCrystal_I2Cload_custom_character(uint8_t char_num, uint8_t *rows){
        LiquidCrystal_I2CcreateChar(char_num, rows);
}

void LiquidCrystal_I2CsetBacklight(uint8_t new_val){
    if(new_val){
        LiquidCrystal_I2Cbacklight();        // turn backlight on
    }else{
        LiquidCrystal_I2CnoBacklight();      // turn backlight off
    }
}
/*
void LiquidCrystal_I2Cprintstr(const char c[]){
    //This function is not identical to the function used for "real" I2C displays
    //it's here so the user sketch doesn't have to be changed 
    //print(c);
    send(c, Rs);
    
}
*/

void LCDI2C4Bit_printIn( char value[] ) 
{
  for ( char *p = value; *p != 0; p++ )
  {
    //LCDI2C4Bit_print(*p);
    send(*p, Rs);
  }
}

    
 /*   
ize_t LiquidCrystal_I2C::write(uint8_t value) {
    send(value, Rs);
    return 0;
}

#else
#include "WProgram.h"

#define printIIC(args)  Wire.send(args)
inline void LiquidCrystal_I2C::write(uint8_t value) {
    send(value, Rs);
}  
    */