Is there a relatively easy way to port LCD code to TFT LCD

Projects Programming
1

Hi

Was just wondering if there is enough commonality between the screens that code could be easily ported from using a standard backlit lcd to being used on a TFT LCD instead.

I am looking to transfer some code and was wondering if there is an easier way than re writing the entire thing in a new format.

Could you set up some rules to redefine the LCD.Print commands as myGLCD.Print instead as long as you do some basic formatting groundwork first? (Just an example of 1 of the differences)

I am going to use a 3.2" TFT lcd screen and shield and the code was designed originally for an older LCD screen.

2

Could you set up some rules to redefine the LCD.Print commands as myGLCD.Print instead as long as you do some basic formatting groundwork first?

That would depend on what classes LCD and myGLCD are instances of. No tap-dancing allowed here.

3

Sorry. myGLCD would be an instance of the UTFT class and LCD would be an instance of LiquidCrystal_SPI_8Bit which is a library written specifically for the code
If I understand your comment. Quite new to Arduino but I am trying to learn a little of each terms definition as it is mentioned.
Today was the turn of classes and instances which I have just tried studying up on.

4

It's helpful, when referring to classes, to provide links to the classes being discussed.

If the UTFT class and the LiquidCrystal_SPI_8Bit class both derive from the same base class (Print), as they should, then substituting one for the other is relatively easy. The class should handle all the magic of getting the device to show some text, for instance, or to draw a red line from here to here. All the user should need to do is determine the method(s) to call to accomplish the required task, and call them with the right data. Drawing a red line from here to there shouldn't require that the program know anything about the physical device that the line is to be drawn on. Think of it as calling out instructions to two friends. One has a white board with some dry erase markers and the other has a pad of paper and some colored pencils. "Draw a vertical line, 3 inches long, starting one inch in from the left edge, and 4 inches down from the top edge, in purple" should be instructions that both of them can understand.

Things get more complicated if the two classes do not share a common base class.

5

Okay. Understood. I was just reading some more about it, and library creation etc. the class definition doesnt look right in the Liquidcrystal one but here it is. I see what you are saying about the .Print comand
This is the utft class from the .cpp file. Sorry codes ran together. LCD is halfway down

class UTFT
{
	public:
		UTFT();
		UTFT(byte model, int RS, int WR,int CS, int RST, int SER=0);
		void	InitLCD(byte orientation=LANDSCAPE);
		void	clrScr();
		void	drawPixel(int x, int y);
		void	drawLine(int x1, int y1, int x2, int y2);
		void	fillScr(byte r, byte g, byte b);
		void	fillScr(word color);
		void	drawRect(int x1, int y1, int x2, int y2);
		void	drawRoundRect(int x1, int y1, int x2, int y2);
		void	fillRect(int x1, int y1, int x2, int y2);
		void	fillRoundRect(int x1, int y1, int x2, int y2);
		void	drawCircle(int x, int y, int radius);
		void	fillCircle(int x, int y, int radius);
		void	setColor(byte r, byte g, byte b);
		void	setColor(word color);
		word	getColor();
		void	setBackColor(byte r, byte g, byte b);
		void	setBackColor(uint32_t color);
		word	getBackColor();
		void	print(char *st, int x, int y, int deg=0);
		void	print(String st, int x, int y, int deg=0);
		void	printNumI(long num, int x, int y, int length=0, char filler=' ');
		void	printNumF(double num, byte dec, int x, int y, char divider='.', int length=0, char filler=' ');
		void	setFont(uint8_t* font);
		uint8_t* getFont();
		uint8_t	getFontXsize();
		uint8_t	getFontYsize();
		void	drawBitmap(int x, int y, int sx, int sy, bitmapdatatype data, int scale=1);
		void	drawBitmap(int x, int y, int sx, int sy, bitmapdatatype data, int deg, int rox, int roy);
		void	lcdOff();
		void	lcdOn();
		void	setContrast(char c);
		int		getDisplayXSize();
		int		getDisplayYSize();


		byte			fch, fcl, bch, bcl;
		byte			orient;
		long			disp_x_size, disp_y_size;
		byte			display_model, display_transfer_mode, display_serial_mode;
		regtype			*P_RS, *P_WR, *P_CS, *P_RST, *P_SDA, *P_SCL, *P_ALE;
		regsize			B_RS, B_WR, B_CS, B_RST, B_SDA, B_SCL, B_ALE;
		_current_font	cfont;
		boolean			_transparent;

		void LCD_Writ_Bus(char VH,char VL, byte mode);
		void LCD_Write_COM(char VL);
		void LCD_Write_DATA(char VH,char VL);
		void LCD_Write_DATA(char VL);
		void LCD_Write_COM_DATA(char com1,int dat1);
		void _hw_special_init();
		void setPixel(word color);
		void drawHLine(int x, int y, int l);
		void drawVLine(int x, int y, int l);
		void printChar(byte c, int x, int y);
		void setXY(word x1, word y1, word x2, word y2);
		void clrXY();
		void rotateChar(byte c, int x, int y, int pos, int deg);
		void _set_direction_registers(byte mode);
		void _fast_fill_16(int ch, int cl, long pix);
		void _fast_fill_8(int ch, long pix);
		void _convert_float(char *buf, double num, int width, byte prec);
};

And the LCD class from the .cpp file
[code]
#include "LiquidCrystal_SPI_8Bit.h"

#include <stdio.h>
#include <string.h>
#include <inttypes.h>
#include "WProgram.h"



// LiquidCrystal_SPI_8Bit constructor is called).

LiquidCrystal_SPI_8Bit::LiquidCrystal_SPI_8Bit(uint8_t rs, uint8_t enable)
{
  init(rs, 255, enable);
}


void LiquidCrystal_SPI_8Bit::init(uint8_t rs, uint8_t rw, uint8_t enable)
{
  pinMode(13, OUTPUT);
  pinMode(12, INPUT);
  pinMode(11, OUTPUT);
  pinMode(10, OUTPUT);
  digitalWrite(10, LOW);
  
  //  set control register enable, master, MSBF, and mode00
  SPCR = (1<<SPE)|(1<<MSTR);
  //SPSR = (1<<SPI2X);   //  Uncomment this line for double clock speed
  
  _rs_pin = rs;
  _rw_pin = rw;
  _enable_pin = enable;
  

  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);
  digitalWrite(_enable_pin, LOW);
  
  
  _displayfunction = LCD_8BITMODE | LCD_1LINE | LCD_5x8DOTS;
  
  begin(16, 1);  
}

void LiquidCrystal_SPI_8Bit::begin(uint8_t cols, uint8_t lines, uint8_t dotsize) {
  if (lines > 1) {
    _displayfunction |= LCD_2LINE;
  }
  _numlines = lines;
  _currline = 0;

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

  
  delayMicroseconds(50000); 
  
  digitalWrite(_rs_pin, LOW);
  digitalWrite(_enable_pin, LOW);
  if (_rw_pin != 255) { 
    digitalWrite(_rw_pin, LOW);
  }
  
  //put the LCD into 8 bit mode
  
  
    /
    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);

}




/********** high level commands, for the user! */
void LiquidCrystal_SPI_8Bit::clear()
{
  command(LCD_CLEARDISPLAY);  // clear display, set cursor position to zero
  delayMicroseconds(2000);  // this command takes a long time!
}

void LiquidCrystal_SPI_8Bit::home()
{
  command(LCD_RETURNHOME);  // set cursor position to zero
  delayMicroseconds(2000);  // this command takes a long time!
}

void LiquidCrystal_SPI_8Bit::setCursor(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
  }
  
  command(LCD_SETDDRAMADDR | (col + row_offsets[row]));
}

// Turn the display on/off (quickly)
void LiquidCrystal_SPI_8Bit::noDisplay() {
  _displaycontrol &= ~LCD_DISPLAYON;
  command(LCD_DISPLAYCONTROL | _displaycontrol);
}
void LiquidCrystal_SPI_8Bit::display() {
  _displaycontrol |= LCD_DISPLAYON;
  command(LCD_DISPLAYCONTROL | _displaycontrol);
}

// Turns the underline cursor on/off
void LiquidCrystal_SPI_8Bit::noCursor() {
  _displaycontrol &= ~LCD_CURSORON;
  command(LCD_DISPLAYCONTROL | _displaycontrol);
}
void LiquidCrystal_SPI_8Bit::cursor() {
  _displaycontrol |= LCD_CURSORON;
  command(LCD_DISPLAYCONTROL | _displaycontrol);
}

// Turn on and off the blinking cursor
void LiquidCrystal_SPI_8Bit::noBlink() {
  _displaycontrol &= ~LCD_BLINKON;
  command(LCD_DISPLAYCONTROL | _displaycontrol);
}
void LiquidCrystal_SPI_8Bit::blink() {
  _displaycontrol |= LCD_BLINKON;
  command(LCD_DISPLAYCONTROL | _displaycontrol);
}

// These commands scroll the display without changing the RAM
void LiquidCrystal_SPI_8Bit::scrollDisplayLeft(void) {
  command(LCD_CURSORSHIFT | LCD_DISPLAYMOVE | LCD_MOVELEFT);
}
void LiquidCrystal_SPI_8Bit::scrollDisplayRight(void) {
  command(LCD_CURSORSHIFT | LCD_DISPLAYMOVE | LCD_MOVERIGHT);
}

// This is for text that flows Left to Right
void LiquidCrystal_SPI_8Bit::leftToRight(void) {
  _displaymode |= LCD_ENTRYLEFT;
  command(LCD_ENTRYMODESET | _displaymode);
}

// This is for text that flows Right to Left
void LiquidCrystal_SPI_8Bit::rightToLeft(void) {
  _displaymode &= ~LCD_ENTRYLEFT;
  command(LCD_ENTRYMODESET | _displaymode);
}

// This will 'right justify' text from the cursor
void LiquidCrystal_SPI_8Bit::autoscroll(void) {
  _displaymode |= LCD_ENTRYSHIFTINCREMENT;
  command(LCD_ENTRYMODESET | _displaymode);
}

// This will 'left justify' text from the cursor
void LiquidCrystal_SPI_8Bit::noAutoscroll(void) {
  _displaymode &= ~LCD_ENTRYSHIFTINCREMENT;
  command(LCD_ENTRYMODESET | _displaymode);
}

// Allows us to fill the first 8 CGRAM locations
// with custom characters
void LiquidCrystal_SPI_8Bit::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]);
  }
}

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

inline void LiquidCrystal_SPI_8Bit::command(uint8_t value) {
  send(value, LOW);
}

inline void LiquidCrystal_SPI_8Bit::write(uint8_t value) {
  send(value, HIGH);
}

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

// write either command or data, with automatic 4/8-bit selection
void LiquidCrystal_SPI_8Bit::send(uint8_t value, uint8_t mode) {
  digitalWrite(_rs_pin, mode);

  // if there is a RW pin indicated, set it low to Write
  if (_rw_pin != 255) { 
    digitalWrite(_rw_pin, LOW);
  }
  
  SPDR = value;
  while(!(SPSR & (1<<SPIF)));
  pulseEnable();
  
}

void LiquidCrystal_SPI_8Bit::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
}

[/code]

6

Posting the header file for one library and the source file for the other isn't really helpful. The header files are what is important.

The two libraries, though, clearly don't share the same base class, since the UTFT class doesn't have a base class. That's a shame, as a lot of code is duplicated in the library.

7

Okay thank you for your help.
I may have to strip it all down and apply the TFT navigation code as approriate instead.

8

Sorry yes I posted the completely wrong thing
So they both dont have the same base class. Can you point me to some reading material about what I need to do in this instance instead perhaps?

class LiquidCrystal_SPI_8Bit : public Print {
public:
  LiquidCrystal_SPI_8Bit(uint8_t rs, uint8_t enable);

  void init(uint8_t rs, uint8_t rw, uint8_t enable);
    
  void begin(uint8_t cols, uint8_t rows, uint8_t charsize = LCD_5x8DOTS);

  void clear();
  void home();

  void noDisplay();
  void display();
  void noBlink();
  void blink();
  void noCursor();
  void cursor();
  void scrollDisplayLeft();
  void scrollDisplayRight();
  void leftToRight();
  void rightToLeft();
  void autoscroll();
  void noAutoscroll();

  void createChar(uint8_t, uint8_t[]);
  void setCursor(uint8_t, uint8_t); 
  virtual void write(uint8_t);
  void command(uint8_t);
private:
  void send(uint8_t, uint8_t);
  void write4bits(uint8_t);
  void write8bits(uint8_t);
  void pulseEnable();

  uint8_t _rs_pin; // LOW: command.  HIGH: character.
  uint8_t _rw_pin; // LOW: write to LCD.  HIGH: read from LCD.
  uint8_t _enable_pin; // activated by a HIGH pulse..

  uint8_t _displayfunction;
  uint8_t _displaycontrol;
  uint8_t _displaymode;

  uint8_t _initialized;

  uint8_t _numlines,_currline;
};

#endif

UTFT

lass UTFT
{
	public:
		UTFT();
		UTFT(byte model, int RS, int WR,int CS, int RST, int SER=0);
		void	InitLCD(byte orientation=LANDSCAPE);
		void	clrScr();
		void	drawPixel(int x, int y);
		void	drawLine(int x1, int y1, int x2, int y2);
		void	fillScr(byte r, byte g, byte b);
		void	fillScr(word color);
		void	drawRect(int x1, int y1, int x2, int y2);
		void	drawRoundRect(int x1, int y1, int x2, int y2);
		void	fillRect(int x1, int y1, int x2, int y2);
		void	fillRoundRect(int x1, int y1, int x2, int y2);
		void	drawCircle(int x, int y, int radius);
		void	fillCircle(int x, int y, int radius);
		void	setColor(byte r, byte g, byte b);
		void	setColor(word color);
		word	getColor();
		void	setBackColor(byte r, byte g, byte b);
		void	setBackColor(uint32_t color);
		word	getBackColor();
		void	print(char *st, int x, int y, int deg=0);
		void	print(String st, int x, int y, int deg=0);
		void	printNumI(long num, int x, int y, int length=0, char filler=' ');
		void	printNumF(double num, byte dec, int x, int y, char divider='.', int length=0, char filler=' ');
		void	setFont(uint8_t* font);
		uint8_t* getFont();
		uint8_t	getFontXsize();
		uint8_t	getFontYsize();
		void	drawBitmap(int x, int y, int sx, int sy, bitmapdatatype data, int scale=1);
		void	drawBitmap(int x, int y, int sx, int sy, bitmapdatatype data, int deg, int rox, int roy);
		void	lcdOff();
		void	lcdOn();
		void	setContrast(char c);
		int		getDisplayXSize();
		int		getDisplayYSize();
		void	setBrightness(byte br);
		void	setDisplayPage(byte page);
		void	setWritePage(byte page);

/*
	The functions and variables below should not normally be used.
	They have been left publicly available for use in add-on libraries
	that might need access to the lower level functions of UTFT.

	Please note that these functions and variables are not documented
	and I do not provide support on how to use them.
*/
		byte			fch, fcl, bch, bcl;
		byte			orient;
		long			disp_x_size, disp_y_size;
		byte			display_model, display_transfer_mode, display_serial_mode;
		regtype			*P_RS, *P_WR, *P_CS, *P_RST, *P_SDA, *P_SCL, *P_ALE;
		regsize			B_RS, B_WR, B_CS, B_RST, B_SDA, B_SCL, B_ALE;
		byte			__p1, __p2, __p3, __p4, __p5;
		_current_font	cfont;
		boolean			_transparent;

		void LCD_Writ_Bus(char VH,char VL, byte mode);
		void LCD_Write_COM(char VL);
		void LCD_Write_DATA(char VH,char VL);
		void LCD_Write_DATA(char VL);
		void LCD_Write_COM_DATA(char com1,int dat1);
		void _hw_special_init();
		void setPixel(word color);
		void drawHLine(int x, int y, int l);
		void drawVLine(int x, int y, int l);
		void printChar(byte c, int x, int y);
		void setXY(word x1, word y1, word x2, word y2);
		void clrXY();
		void rotateChar(byte c, int x, int y, int pos, int deg);
		void _set_direction_registers(byte mode);
		void _fast_fill_16(int ch, int cl, long pix);
		void _fast_fill_8(int ch, long pix);
		void _convert_float(char *buf, double num, int width, byte prec);
};

#endif
9

Can you point me to some reading material about what I need to do in this instance instead perhaps?

I think you already know the answer to this - completely re-write your program.

10

Straws needed to be grasped at.
Thanks Paul