//---------------------------------------------------------------------------------------
// Programm Nr.: 07
// Content     : LCD 2x16 characters with HD44780 - Routinen
// Author      : digital AG Halle
// Date        : 14.07.2008
// System      : ATmega8-16PU - Dai Hoc Hue Development Board
//---------------------------------------------------------------------------------------

//--included Files-----------------------------------------------------------------------

#include <avr/io.h>
#include <util/delay.h>	//important for the LCD-protocol timing 
			//works only with compiler optimization 00 !!!

//--declarations-------------------------------------------------------------------------

#ifndef F_CPU
#define F_CPU 8000000	//CPU frequency = 8 MHz
#endif

/*----------------------------------------------------------
In this implementation, the LCD is used in the most easy way 
the 4-bit-mode. Only 6 lines are needed for this - but you
don't read lcd status - you just wait a standard time
----------------------------------------------------------*/

#define LCD_PORT      PORTD
#define LCD_DDR       DDRD
#define LCD_RS        0x04
#define LCD_EN        5

//implement in your project only the needed routines!
void lcd_enable(void);	  	    	//setup communication to the lcd
void lcd_data(unsigned char temp1);	//send a byte to the lcd
void lcd_clear(void);			//erase all displayed signs
void lcd_init(void);			//initialise lcd
void set_cursor(uint8_t x, uint8_t y);	//set cursor to position x,y
void lcd_string(char *data);		//send a string to the lcd

//--MAIN PROGRAMM------------------------------------------------------------------------

int main(void)
{

	//--INITIALISATION---------------------------------------------------------------

	DDRD=255; 	//Port D: all Bits defined as output (for the status LEDs)


	//--PROGRAMM CODE BEFORE MAIN LOOP (USED JUST ONE TIME)--------------------------

	lcd_init();	//call of the lcd-init routine

	//--MAIN LOOP--------------------------------------------------------------------
	
	while(1)
	{
	}
	return 0;
}

//--MAIN PROGRAMM END--------------------------------------------------------------------

//--EXTERNAL ROUTINES (FOR THE LCD)------------------------------------------------------

void lcd_data(unsigned char temp1) //send a data byte to the lcd
{
   unsigned char temp2 = temp1;
 
   LCD_PORT |= (1<<LCD_RS);        // set line RS to 1 
 
   temp1 = temp1 >> 4;
   temp1 = temp1 & 0x0F;
   LCD_PORT &= 0xF0;
   LCD_PORT |= temp1;               // set
   lcd_enable();
 
   temp2 = temp2 & 0x0F;
   LCD_PORT &= 0xF0;
   LCD_PORT |= temp2;               // set
   lcd_enable();
   
   _delay_us(42);
}

void lcd_command(unsigned char temp1) //send a command to the lcd
{
   unsigned char temp2 = temp1;
 
   LCD_PORT &= ~(1<<LCD_RS);        // set RS to 0 
 
   temp1 = temp1 >> 4;              // get high nibble
   temp1 = temp1 & 0x0F;            // mask
   LCD_PORT &= 0xF0;
   LCD_PORT |= temp1;               // set
   lcd_enable();
 
   temp2 = temp2 & 0x0F;            // get and mask low nibble
   LCD_PORT &= 0xF0;
   LCD_PORT |= temp2;               // set
   lcd_enable();
   
   _delay_us(42);
}

void lcd_enable(void)		//send the enable puls to the lcd
{
   LCD_PORT |= (1<<LCD_EN);
    _delay_us(1);                   
   LCD_PORT &= ~(1<<LCD_EN);
}

void lcd_init(void)		//initialize the lcd
{
   LCD_DDR = LCD_DDR | 0x0F | (1<<LCD_RS) | (1<<LCD_EN);   // Port auf Ausgang schalten
 
   //for intitialization do this 3 times !
 
   _delay_ms(15);
   LCD_PORT &= 0xF0;
   LCD_PORT |= 0x03;            
   LCD_PORT &= ~(1<<LCD_RS);      // RS to 0
   lcd_enable();
 
   _delay_ms(5);
   lcd_enable();
 
   _delay_ms(1);
   lcd_enable();
 
   //activate 4-bit-mode
   LCD_PORT &= 0xF0;
   LCD_PORT |= 0x02;
   lcd_enable();
 
   //mode: 4-bit; 2 rows; character of 5x7 dots
   lcd_command(0x28);
    
   //lcd on; cursor off; no blinking
   lcd_command(0x0C); 
 
   //increment; no scrolling
   lcd_command(0x06);
 
   lcd_clear();
}
 
void lcd_clear(void) 		//cleares the full lcd content
{
   lcd_command(0x01);
   _delay_ms(5);
}
 
void lcd_home(void)		//set the cursor to x0,y0
{
   lcd_command(0x02);
   _delay_ms(5);
}
 
void set_cursor(uint8_t x, uint8_t y) 	//set cursor to another position
					//x=0,1 (row); y=0-20 (colum)
{
  switch (y) {
    case 1: lcd_command(0x80+0x00+x); break;    // 1st row
    case 2: lcd_command(0x80+0x40+x); break;    // 2nd row
  }
}
 
void lcd_string(char *data)	//send a string to the lcd
{
    while(*data) {
        lcd_data(*data);
        data++;
    }
}

//--PROGRAMM END-------------------------------------------------------------------------