HD44780 Dot Matrix LCD Controller/Driver, PIC16F877A

/*------------------------------------------
LCD library 4 bit data bus. HD44780 Dot
Matrix LCD Controller/river

-------------------------------------------*/
#define LCD_RS      RD1
#define LCD_RW      RD2
#define LCD_EN      RD0
#define LCD_LIGHT   RD3
#define LCD_DATA    PORTD       //D7-D4
#define LCD_PULSE lcd_pulse
#define _XTAL_FREQ  20000000
#define FUNCTION_SET_8_BIT  0b00110000
#define FUNCTION_SET_4_BIT  0b00100000
#define DISPLAY_CLEAR   0b00000001
#define __delay_cycles _delay
void LCD_command(unsigned char command);
void LCD_data(unsigned char data);
void lcd_init(void);
void clear_LCD();
void display_LCD(char line_number,char position, unsigned char *message);
void lcd_putch (unsigned char c);
void lcd_putc (unsigned char *s1);
void lcd_string (unsigned char *s1);
void lcd_gotoxy(char line_number,char position);
void LCD_delay (void);

void LCD_command(unsigned char command)
{
    unsigned char temp;
    LCD_RS = 0;  //Pin RS should be LOW for sending command

    // To send MSB part of command
    temp = (command & 0xf0); //[(0x38 & 0xf0)= 0x30 ==> 0x30]
    LCD_DATA &= 0x0F;
    LCD_DATA |= temp;
    LCD_EN = 1;
    __delay_us(2);
    LCD_EN = 0;
    LCD_delay();

    temp = ((command & 0x0f)<<4); //[(0x38 & 0x0f)= 0x08<<4 ==> 0x80]
    LCD_DATA &= 0x0F;
    LCD_DATA |= temp;
    LCD_EN = 1;
    __delay_us(2);
    LCD_EN = 0;
    __delay_ms(1);
}

void LCD_data(unsigned char data)
{
    unsigned char temp;
    LCD_RS=1; //Pin RS should be HIGH for sending data

    temp =(data & 0xf0);
    LCD_DATA &= 0x0F;
    LCD_DATA |= temp;
    LCD_EN = 1;
    __delay_us(2);
    LCD_EN = 0;

    temp = ((data & 0x0f)<<4);
    LCD_DATA &= 0x0F;
    LCD_DATA |= temp;
    LCD_EN = 1;
    __delay_us(2);
    LCD_EN = 0;
    __delay_ms(1);
}

void lcd_init(void)
{
    char a;
    TRISD = 0x00;
    LCD_DATA = 0x00; //DATA or COMMAND i/p to LCD
    //CONTROL i/p to LCD

    LCD_EN=0;
    LCD_RW=0;
    __delay_ms(50);
    LCD_DATA|=0x30;
    LCD_RS=0;
    LCD_EN=1;
    for (a=0;a<=3;a++)
    {
        LCD_EN=1;
        __delay_ms(1);
        LCD_EN=0;
        __delay_ms(1);
    }
    LCD_DATA = LCD_DATA & 0x0F;
    LCD_DATA = LCD_DATA | 0x20;
    __delay_ms(50);
    LCD_EN = 0;
    LCD_EN = 1;
    __delay_ms(50);
    LCD_EN = 0;

    __delay_ms(2);
    LCD_command(0x28);  //set 4-bit mode and 2 lines
    __delay_ms(2);
    LCD_command(0x10);  //cursor move & shift left
    __delay_ms(2);
    LCD_command(0x06);  //entry mode = increment
    __delay_ms(2);
    LCD_command(0x0c);  //display on - cursor blink on
    __delay_ms(2);
    LCD_command(0x01);  //clear display
    __delay_ms(2);
    __delay_ms(1);
}

void clear_LCD( )
{
    LCD_command(0x01);
    __delay_ms(1);
}

void display_LCD(char line_number,char position, unsigned char *message)
{
    int a;
    if(line_number==1)
    {
        a=0x80+position;
        LCD_command(a);
    }
    else if(line_number==2)
    {
        a=0xC0+position;
        LCD_command(a);
    }
    while(*message!=0)
    {   //printf (" %c", *message);
        LCD_data(*message);
        __delay_ms(15);
        message++;
    }
}

void lcd_putch (unsigned char c)
{
    if (c == '\f')
    {
        clear_LCD( ); //Clear LCD
    }
    else if (c == '\n')
    {
        LCD_command (0XC0); //New Line
    }
    else
    {
        LCD_data( c); //Show the character
    }
}

void lcd_putc (unsigned char *s1)
{
    while (*s1!=0)
    {
        lcd_putch( *s1);
        __delay_ms(5);
        s1++;
    }
}

void lcd_string (unsigned char *s1)
{
    lcd_putc (*s1);
}

void lcd_gotoxy(char line_number,char position)
{
    int a;
    if(line_number==1)
    {
        a=0x80+position;
        LCD_command(a);
    }
    else if(line_number==2)
    {
        a=0xC0+position;
        LCD_command(a);
    }
}

void LCD_delay (void)
{
    int t;
    for (t=0; t<250; t++);
}