Initial commit

Fork of TextLCD by Wim Huiskamp

Files at this revision

API Documentation at this revision

Comitter:
wim
Date:
Sat Feb 09 15:10:36 2013 +0000
Parent:
12:6bf9d9957d31
Child:
14:0c32b66b14b8
Commit message:
First version with I2C interface, refactored code

Changed in this revision

TextLCD.cpp Show annotated file Show diff for this revision Revisions of this file
TextLCD.h Show annotated file Show diff for this revision Revisions of this file
--- a/TextLCD.cpp	Tue Feb 05 21:50:43 2013 +0000
+++ b/TextLCD.cpp	Sat Feb 09 15:10:36 2013 +0000
@@ -24,90 +24,127 @@
 #include "TextLCD.h"
 #include "mbed.h"
 
-TextLCD::TextLCD(PinName rs, PinName e, PinName d4, PinName d5,
-                 PinName d6, PinName d7, LCDType type) : _rs(rs),
-        _e(e), _d(d4, d5, d6, d7),
+TextLCD::TextLCD(PinName rs, PinName e,
+                 PinName d4, PinName d5, PinName d6, PinName d7,
+                 LCDType type): _rs(rs), _e(e),
+                                _d(d4, d5, d6, d7),
+                                _type(type) {
+
+
+  _busType = _PinBus;
+
+  _init();
+
+}
+
+
+TextLCD::TextLCD(I2C *i2c, char deviceAddress, LCDType type) :
+        _rs(NC), _e(NC), _d(NC),
+        _i2c(i2c),
         _type(type) {
+        
+  _slaveAddress = deviceAddress;
+  _busType = _I2CBus;
 
-    _e  = 1;
-    _rs = 0;            // command mode
+  
+  // Init the portexpander bus
+  _lcd_bus = 0x80;
+  
+  // write the new data to the portexpander
+  _i2c->write(_slaveAddress, &_lcd_bus, 1);    
+
+  _init();
+    
+}
 
+/** Init the LCD controller
+ *  4-bit mode, number of lines, no cursor etc
+ *  Clear display 
+ */
+void TextLCD::_init() {
+//    _e  = 1;  
+//    _rs = 0;            // command mode
+
+    _setEnable(true);    
+    _setRS(false);      // command mode
+    
     wait(0.015);        // Wait 15ms to ensure powered up
 
     // send "Display Settings" 3 times (Only top nibble of 0x30 as we've got 4-bit bus)
     for (int i=0; i<3; i++) {
-        writeByte(0x3);
+        _writeByte(0x3);
         wait(0.00164);  // this command takes 1.64ms, so wait for it
     }
-    writeByte(0x2);     // 4-bit mode
-    wait(0.000040f);    // most instructions take 40us
+    _writeByte(0x2);     // 4-bit mode
+    wait(0.000040f);     // most instructions take 40us
 
     // Display is now in 4-bit mode
     switch (_type) {
         case LCD8x1:
-            writeCommand(0x20); // Function set 001 BW N F - -
-                                //   N=0 (1 line)
-                                //   F=0 (5x7 dots font)
+            _writeCommand(0x20); // Function set 001 BW N F - -
+                                 //   N=0 (1 line)
+                                 //   F=0 (5x7 dots font)
             break;                                
             
         case LCD24x4:
             // Special mode for KS0078
-            writeCommand(0x2A); // Function set 001 BW N RE DH REV
-                                //    N=1  (Dont care for KS0078)
-                                //   RE=0  (Extended Regs, special mode for KS0078)
-                                //   DH=1  (Disp shift, special mode for KS0078)                                
-                                //   REV=0 (Reverse, special mode for KS0078)
+            _writeCommand(0x2A); // Function set 001 BW N RE DH REV
+                                 //    N=1  (Dont care for KS0078)
+                                 //   RE=0  (Extended Regs, special mode for KS0078)
+                                 //   DH=1  (Disp shift, special mode for KS0078)                                
+                                 //   REV=0 (Reverse, special mode for KS0078)
 
-            writeCommand(0x2E); // Function set 001 BW N RE DH REV
-                                //    N=1  (Dont care for KS0078)
-                                //   RE=1  (Ena Extended Regs, special mode for KS0078)
-                                //   DH=1  (Disp shift, special mode for KS0078)                                
-                                //   REV=0 (Reverse, special mode for KS0078)
+            _writeCommand(0x2E); // Function set 001 BW N RE DH REV
+                                 //    N=1  (Dont care for KS0078)
+                                 //   RE=1  (Ena Extended Regs, special mode for KS0078)
+                                 //   DH=1  (Disp shift, special mode for KS0078)                                
+                                 //   REV=0 (Reverse, special mode for KS0078)
 
-            writeCommand(0x09); // Ext Function set 0000 1 FW BW NW
-                                //   FW=0  (5-dot font, special mode for KS0078)
-                                //   BW=0  (Cur BW invert disable, special mode for KS0078)
-                                //   NW=1  (4 Line, special mode for KS0078)                                
+            _writeCommand(0x09); // Ext Function set 0000 1 FW BW NW
+                                 //   FW=0  (5-dot font, special mode for KS0078)
+                                 //   BW=0  (Cur BW invert disable, special mode for KS0078)
+                                 //   NW=1  (4 Line, special mode for KS0078)                                
 
-            writeCommand(0x2A); // Function set 001 BW N RE DH REV
-                                //    N=1  (Dont care for KS0078)
-                                //   RE=0  (Dis. Extended Regs, special mode for KS0078)
-                                //   DH=1  (Disp shift, special mode for KS0078)                                
-                                //   REV=0 (Reverse, special mode for KS0078)
+            _writeCommand(0x2A); // Function set 001 BW N RE DH REV
+                                 //    N=1  (Dont care for KS0078)
+                                 //   RE=0  (Dis. Extended Regs, special mode for KS0078)
+                                 //   DH=1  (Disp shift, special mode for KS0078)                                
+                                 //   REV=0 (Reverse, special mode for KS0078)
             break;
                                             
         default:
-            writeCommand(0x28); // Function set 001 BW N F - -
-                                //   N=1 (2 lines)
-                                //   F=0 (5x7 dots font)
+            _writeCommand(0x28); // Function set 001 BW N F - -
+                                 //   N=1 (2 lines)
+                                 //   F=0 (5x7 dots font)
+                                 //    -  (Don't care)                                
             
             break;
     }
 
-    writeCommand(0x06); // Entry Mode 0000 01 CD S 
-                        //   Cursor Direction and Display Shift
-                        //   CD=1 (Cur incr)
-                        //   S=0  (No display shift)                        
+    _writeCommand(0x06); // Entry Mode 0000 01 CD S 
+                         //   Cursor Direction and Display Shift
+                         //   CD=1 (Cur incr)
+                         //   S=0  (No display shift)                        
 
-//    writeCommand(0x0C); // Display Ctrl 0000 1 D C B
-//                        //   Display On, Cursor Off, Blink Off
-    cursor(TextLCD::CurOff_BlkOff);  
+//    _writeCommand(0x0C); // Display Ctrl 0000 1 D C B
+//                         //   Display On, Cursor Off, Blink Off
+    setCursor(TextLCD::CurOff_BlkOff);  
     
     cls();    
 }
 
 
-void TextLCD::character(int column, int row, int c) {
+void TextLCD::_character(int column, int row, int c) {
     int addr = getAddress(column, row);
     
-    writeCommand(0x80 | addr);
-    writeData(c);
+    _writeCommand(0x80 | addr);
+    _writeData(c);
 }
 
 
 void TextLCD::cls() {
-    writeCommand(0x01); // cls, and set cursor to 0
-    wait(0.00164f);     // This command takes 1.64 ms
+    _writeCommand(0x01); // cls, and set cursor to 0
+    wait(0.00164f);      // This command takes 1.64 ms
     locate(0, 0);
 }
 
@@ -124,7 +161,7 @@
             _row = 0;
         }
     } else {
-        character(_column, _row, value);
+        _character(_column, _row, value);
         _column++;
         if (_column >= columns()) {
             _column = 0;
@@ -141,27 +178,135 @@
     return -1;
 }
 
-void TextLCD::writeByte(int value) {
-    _d = value >> 4;
+
+void TextLCD::_setEnable(bool value) {
+
+  switch(_busType) {
+    case _PinBus : 
+                    if (value)
+                      _e  = 1;    // Set E bit 
+                    else  
+                      _e  = 0;    // Reset E bit  
+
+                    break;  
+    
+    case _I2CBus : 
+                    if (value)
+                      _lcd_bus |= D_LCD_E;     // Set E bit 
+                    else                     
+                      _lcd_bus &= ~D_LCD_E;    // Reset E bit                     
+
+                    // write the new data to the portexpander
+                    _i2c->write(_slaveAddress, &_lcd_bus, 1);    
+                   
+                   break;  
+    
+    case _SPIBus :
+                   break;
+  }
+}    
+
+void TextLCD::_setRS(bool value) {
+
+  switch(_busType) {
+    case _PinBus : 
+                    if (value)
+                      _rs  = 1;    // Set RS bit 
+                    else  
+                      _rs  = 0;    // Reset RS bit 
+
+                    break;  
+    
+    case _I2CBus : 
+                    if (value)
+                      _lcd_bus |= D_LCD_RS;    // Set RS bit 
+                    else                     
+                      _lcd_bus &= ~D_LCD_RS;   // Reset RS bit                     
+
+                    // write the new data to the portexpander
+                    _i2c->write(_slaveAddress, &_lcd_bus, 1);    
+                   
+                   break;
+                       
+    case _SPIBus :
+                   break;
+  }
+
+}    
+
+void TextLCD::_setData(int value) {
+  int data;
+  
+  switch(_busType) {
+    case _PinBus : 
+                    _d = value & 0x0F;   // Write Databits 
+
+                    break;  
+    
+    case _I2CBus : 
+                    data = value & 0x0F;
+                    if (data & 0x01)
+                      _lcd_bus |= D_LCD_D4;   // Set Databit 
+                    else                     
+                      _lcd_bus &= ~D_LCD_D4;  // Reset Databit                     
+
+                    if (data & 0x02)
+                      _lcd_bus |= D_LCD_D5;   // Set Databit 
+                    else                     
+                      _lcd_bus &= ~D_LCD_D5;  // Reset Databit                     
+
+                    if (data & 0x04)
+                      _lcd_bus |= D_LCD_D6;   // Set Databit 
+                    else                     
+                      _lcd_bus &= ~D_LCD_D6;  // Reset Databit                     
+
+                    if (data & 0x08)
+                      _lcd_bus |= D_LCD_D7;   // Set Databit 
+                    else                     
+                      _lcd_bus &= ~D_LCD_D7;  // Reset Databit                     
+                    
+                    // write the new data to the portexpander
+                    _i2c->write(_slaveAddress, &_lcd_bus, 1);  
+                   
+                    break;                    
+                    
+    case _SPIBus :
+                    break;
+  }
+
+}    
+
+
+
+void TextLCD::_writeByte(int value) {
+//    _d = value >> 4;
+    _setData(value >> 4);
     wait(0.000040f); // most instructions take 40us
-    _e = 0;
+//    _e = 0;
+    _setEnable(false);
     wait(0.000040f);
-    _e = 1;
-    _d = value >> 0;
+//    _e = 1;
+    _setEnable(true);        
+//    _d = value >> 0;
+    _setData(value >> 0);    
     wait(0.000040f);
-    _e = 0;
+//    _e = 0;
+    _setEnable(false);    
     wait(0.000040f);  // most instructions take 40us
-    _e = 1;
+//    _e = 1;
+    _setEnable(true);    
 }
 
-void TextLCD::writeCommand(int command) {
-    _rs = 0;
-    writeByte(command);
+void TextLCD::_writeCommand(int command) {
+//    _rs = 0;
+    _setRS(false);        
+    _writeByte(command);
 }
 
-void TextLCD::writeData(int data) {
-    _rs = 1;
-    writeByte(data);
+void TextLCD::_writeData(int data) {
+//    _rs = 1;
+    _setRS(true);            
+    _writeByte(data);
 }
 
 
@@ -170,7 +315,7 @@
 // It is confusing since it returns the memoryaddress or-ed with the set memorycommand 0x80.
 // Left it in here for compatibility with older code. New applications should use getAddress() instead.
 // 
-int TextLCD::address(int column, int row) {
+int TextLCD::_address(int column, int row) {
     switch (_type) {
         case LCD20x4:
             switch (row) {
@@ -196,7 +341,7 @@
 
 // This replaces the original method.
 // Left it in here for compatibility with older code. New applications should use getAddress() instead.
-int TextLCD::address(int column, int row) {
+int TextLCD::_address(int column, int row) {
   return 0x80 | getAddress(column, row);
 }
 
@@ -208,6 +353,13 @@
         case LCD8x1:
             return 0x00 + column;                        
     
+        case LCD16x1:
+            // LCD16x1 is a special layout of LCD8x2
+            if (column<8) 
+              return 0x00 + column;                        
+            else   
+              return 0x40 + (column - 8);                        
+
         case LCD16x4:
             switch (row) {
                 case 0:
@@ -263,7 +415,7 @@
 }
 
 
-// Added for consistency. Set row, colum and update memoryaddress.
+// Added for consistency. Set row, column and update memoryaddress.
 //
 void TextLCD::setAddress(int column, int row) {
 
@@ -271,7 +423,7 @@
     
     int addr = getAddress(column, row);
     
-    writeCommand(0x80 | addr);
+    _writeCommand(0x80 | addr);
 }
 
 int TextLCD::columns() {
@@ -280,6 +432,7 @@
         case LCD8x2:
             return 8;
 
+        case LCD16x1:        
         case LCD16x2:
         case LCD16x2B:
         case LCD16x4:        
@@ -305,6 +458,7 @@
 int TextLCD::rows() {
     switch (_type) {
         case LCD8x1: 
+        case LCD16x1:         
             return 1;           
 
         case LCD8x2:        
@@ -327,25 +481,25 @@
 }
 
 
-void TextLCD::cursor(TextLCD::LCDCursor show) { 
+void TextLCD::setCursor(TextLCD::LCDCursor show) { 
     
     switch (show) {
-      case CurOff_BlkOff : writeCommand(0x0C); // Cursor off and Blink Off
+      case CurOff_BlkOff : _writeCommand(0x0C); // Cursor off and Blink Off
                            wait_us(40);
                            _cursor = show;
                            break;
 
-      case CurOn_BlkOff   : writeCommand(0x0E); // Cursor on and Blink Off
+      case CurOn_BlkOff   : _writeCommand(0x0E); // Cursor on and Blink Off
                            wait_us(40);  
                            _cursor = show;
                            break;
 
-      case CurOff_BlkOn :  writeCommand(0x0D); // Cursor off and Blink On
+      case CurOff_BlkOn :  _writeCommand(0x0D); // Cursor off and Blink On
                            wait_us(40);
                            _cursor = show;
                            break;
 
-      case CurOn_BlkOn   : writeCommand(0x0F); // Cursor on and Blink char
+      case CurOn_BlkOn   : _writeCommand(0x0F); // Cursor on and Blink char
                            wait_us(40);  
                            _cursor = show;
                            break;
@@ -360,10 +514,10 @@
 
 
 void TextLCD::setUDC(unsigned char c, char *udc_data) {
-  writeCommand(0x40 + ((c & 0x07) << 3)); //Set CG-RAM address
+  _writeCommand(0x40 + ((c & 0x07) << 3)); //Set CG-RAM address
 
   for (int i=0; i<8; i++) {
-    writeData(*udc_data++);
+    _writeData(*udc_data++);
   }
 }
 
--- a/TextLCD.h	Tue Feb 05 21:50:43 2013 +0000
+++ b/TextLCD.h	Sat Feb 09 15:10:36 2013 +0000
@@ -1,6 +1,7 @@
 /* mbed TextLCD Library, for a 4-bit LCD based on HD44780
  * Copyright (c) 2007-2010, sford, http://mbed.org
- *               2013, WH, Added LCD types, fixed LCD address issues, added Cursor and UDCs 
+ *               2013, v01: WH, Added LCD types, fixed LCD address issues, added Cursor and UDCs 
+ *               2013, v02: WH, Added I2C and SPI bus interfaces 
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -42,7 +43,38 @@
  * @endcode
  */
 
-/** User Defined Chars 5x7 dots */
+
+//Pin Defines for I2C PCF8574 and SPI 74595 Bus
+//LCD and serial portexpanders should be wired accordingly 
+//Note: LCD RW pin must be connected to GND
+//      E2 may be used for future expansion to LCD40x4
+//      BL may be used for future expansion to control backlight
+//
+#define D_LCD_PIN_D4   0x00
+#define D_LCD_PIN_D5   0x01
+#define D_LCD_PIN_D6   0x02
+#define D_LCD_PIN_D7   0x03
+#define D_LCD_PIN_RS   0x04
+#define D_LCD_PIN_E    0x05
+#define D_LCD_PIN_E2   0x06
+#define D_LCD_PIN_BL   0x07
+
+#define D_LCD_BUS_MSK  0x0F
+
+//Bitpattern Defines for I2C PCF8574 and SPI 74595 Bus
+//
+#define D_LCD_D4       (1<<D_LCD_PIN_D4)
+#define D_LCD_D5       (1<<D_LCD_PIN_D5)
+#define D_LCD_D6       (1<<D_LCD_PIN_D6)
+#define D_LCD_D7       (1<<D_LCD_PIN_D7)
+#define D_LCD_RS       (1<<D_LCD_PIN_RS)
+#define D_LCD_E        (1<<D_LCD_PIN_E)
+#define D_LCD_E2       (1<<D_LCD_PIN_E2)
+#define D_LCD_BL       (1<<D_LCD_PIN_BL)
+
+
+
+/** Some sample User Defined Chars 5x7 dots */
 const char udc_ae[] = {0x00, 0x00, 0x1B, 0x05, 0x1F, 0x14, 0x1F, 0x00};  //æ
 const char udc_0e[] = {0x00, 0x00, 0x0E, 0x13, 0x15, 0x19, 0x0E, 0x00};  //ø
 const char udc_ao[] = {0x0E, 0x0A, 0x0E, 0x01, 0x0F, 0x11, 0x0F, 0x00};  //å
@@ -59,10 +91,28 @@
 const char udc_6[]  = {0x15, 0x0a, 0x15, 0x0a, 0x15, 0x0a, 0x15, 0x00};  // checkerboard
 const char udc_7[]  = {0x10, 0x08, 0x04, 0x02, 0x01, 0x00, 0x10, 0x00};  // \
 
+const char udc_degr[]   = {0x06, 0x09, 0x09, 0x06, 0x00, 0x00, 0x00, 0x00};  // Degree symbol
+
+const char udc_TM_T[]   = {0x1F, 0x04, 0x04, 0x04, 0x00, 0x00, 0x00, 0x00};  // Trademark T
+const char udc_TM_M[]   = {0x11, 0x1B, 0x15, 0x11, 0x00, 0x00, 0x00, 0x00};  // Trademark M
+
+//const char udc_Bat_Hi[] = {0x0E, 0x1F, 0x1F, 0x1F, 0x1F, 0x1F, 0x1F, 0x00};  // Battery Full
+//const char udc_Bat_Ha[] = {0x0E, 0x11, 0x13, 0x17, 0x1F, 0x1F, 0x1F, 0x00};  // Battery Half
+//const char udc_Bat_Lo[] = {0x0E, 0x11, 0x11, 0x11, 0x11, 0x11, 0x1F, 0x00};  // Battery Low
+const char udc_Bat_Hi[] = {0x0E, 0x1F, 0x1F, 0x1F, 0x1F, 0x1F, 0x1F, 0x00};  // Battery Full
+const char udc_Bat_Ha[] = {0x0E, 0x11, 0x11, 0x1F, 0x1F, 0x1F, 0x1F, 0x00};  // Battery Half
+const char udc_Bat_Lo[] = {0x0E, 0x11, 0x11, 0x11, 0x11, 0x1F, 0x1F, 0x00};  // Battery Low
+
+const char udc_bar_1[]  = {0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x00};  // Bar 1
+const char udc_bar_2[]  = {0x18, 0x18, 0x18, 0x18, 0x18, 0x18, 0x18, 0x00};  // Bar 11
+const char udc_bar_3[]  = {0x1C, 0x1C, 0x1C, 0x1C, 0x1C, 0x1C, 0x1C, 0x00};  // Bar 111
+const char udc_bar_4[]  = {0x17, 0x17, 0x17, 0x17, 0x17, 0x17, 0x17, 0x00};  // Bar 1111
+const char udc_bar_5[]  = {0x1F, 0x1F, 0x1F, 0x1F, 0x1F, 0x1F, 0x1F, 0x00};  // Bar 11111
+
 
 /** A TextLCD interface for driving 4-bit HD44780-based LCDs
  *
- * Currently supports 8x1, 8x2, 16x2, 16x4, 20x2, 20x4, 24x2, 24x4 and 40x2 panels
+ * Currently supports 8x1, 8x2, 16x1, 16x2, 16x4, 20x2, 20x4, 24x2, 24x4 and 40x2 panels
  *
  */
 class TextLCD : public Stream {
@@ -71,7 +121,8 @@
     /** LCD panel format */
     enum LCDType {
         LCD8x1,     /**<  8x1 LCD panel */    
-        LCD8x2,     /**<  8x2 LCD panel */            
+        LCD8x2,     /**<  8x2 LCD panel */          
+        LCD16x1,    /**< 16x1 LCD panel (actually 8x2) */          
         LCD16x2,    /**< 16x2 LCD panel (default) */
         LCD16x2B,   /**< 16x2 LCD panel alternate addressing */
         LCD16x4,    /**< 16x4 LCD panel */        
@@ -91,7 +142,7 @@
     };
 
 
-    /** Create a TextLCD interface
+    /** Create a TextLCD interface for using regural mbed pins
      *
      * @param rs    Instruction/data control line
      * @param e     Enable line (clock)
@@ -99,6 +150,24 @@
      * @param type  Sets the panel size/addressing mode (default = LCD16x2)
      */
     TextLCD(PinName rs, PinName e, PinName d4, PinName d5, PinName d6, PinName d7, LCDType type = LCD16x2);
+    
+    /** Create a TextLCD interface using an I2C PC8574 portexpander
+     *
+     * @param i2c             I2C Bus
+     * @param deviceAddress   I2C slave address (PCF8574)
+     * @param type            Sets the panel size/addressing mode (default = LCD16x2)
+     */
+    TextLCD(I2C *i2c, char deviceAddress, LCDType type = LCD16x2);
+
+
+    /** Create a TextLCD interface using an SPI 74595 portexpander
+     *
+     * @param spi             SPI Bus
+     * @param cs              chip select pin (active low)
+     * @param type            Sets the panel size/addressing mode (default = LCD16x2)
+     */
+//    TextLCD(SPI *spi, PinName cs, LCDType type = LCD16x2);
+
 
 #if DOXYGEN_ONLY
     /** Write a character to the LCD
@@ -159,7 +228,7 @@
      *
      * @param show    The Cursor mode (CurOff_BlkOff, CurOn_BlkOff, CurOff_BlkOn, CurOn_BlkOn)
      */
-    void cursor(LCDCursor show);     
+    void setCursor(LCDCursor show);     
 
 
     /** Set User Defined Characters
@@ -170,20 +239,56 @@
     void setUDC(unsigned char c, char *udc_data);
 
 protected:
+   /** LCD Bus control */
+    enum _LCDBus {
+        _PinBus,  /**<  Regular mbed pins */    
+        _I2CBus,  /**<  I2C PCF8574 Portexpander */    
+        _SPIBus   /**<  SPI 74595 */    
+    };
+
     // Stream implementation functions
     virtual int _putc(int value);
     virtual int _getc();
 
-    int  address(int column, int row);
-    void character(int column, int row, int c);
-    void writeByte(int value);
-    void writeCommand(int command);
-    void writeData(int data);
+    void _init();    
+    int  _address(int column, int row);
+    void _character(int column, int row, int c);
+    
+//Low level writes to LCD Bus (serial or parallel)
+    void _setEnable(bool value);
+    void _setRS(bool value);  
+    void _setData(int value);
 
+//Low level writes to LCD serial bus only
+    void _writeBus();      
+
+//Low level writes to LCD
+    void _writeByte(int value);
+    void _writeCommand(int command);
+    void _writeData(int data);
+  
+// Regular mbed pins bus
     DigitalOut _rs, _e;
     BusOut _d;
+    
+// I2C bus    
+    I2C *_i2c;
+    unsigned char _slaveAddress;
+    
+// SPI bus        
+//    SPI *_spi;
+//    DigitalOut _cs;    
+    
+//Bus Interface type    
+    _LCDBus _busType;
+
+// Internal bus mirror value for serial only
+    char _lcd_bus;   
+    
+//Display type
     LCDType _type;
 
+// Cursor
     int _column;
     int _row;
     LCDCursor _cursor;