#define F_CPU 8000000UL
#include <avr/io.h>           /* Include AVR std. library file */
#include <util/delay.h>         /* Include inbuilt defined Delay header file */

#define RS PB3              /* Define Register Select (data reg./command reg.) signal pin */
#define EN PB2              /* Define Enable signal pin */


void lcd_sending_command( unsigned char cmnd )
{
  PORTB = (cmnd & 0xF0); /* sending upper nibble */
  PORTB &= ~ (1<<RS);       /* RS=0, command reg. */
  PORTB |= (1<<EN);       /* Enable pulse */
  _delay_us(1);
  PORTB &= ~ (1<<EN);
  PORTB = (cmnd << 4);  /* sending lower nibble */
  PORTB |= (1<<EN);
  _delay_us(1);
  PORTB &= ~ (1<<EN);
  _delay_ms(2);
}


void lcd_sending_data( unsigned char data )
{
  PORTB =  (data & 0xF0); /* sending upper nibble */
  PORTB |= (1<<RS);       /* RS=1, data reg. */
  PORTB|= (1<<EN);
  _delay_us(1);
  PORTB &= ~ (1<<EN);
  PORTB = (data << 4); /* sending lower nibble */
  PORTB |= (1<<RS);
  PORTB |= (1<<EN);
  _delay_us(1);
  PORTB &= ~ (1<<EN);
  _delay_ms(2);
}


void lcd_initialization (void)          /* LCD Initialize function */
{
  DDRB = 0xFF;            /* Make LCD command port direction as o/p */
  _delay_ms(20);            /* LCD Power ON delay always >15ms */
  lcd_sending_command(0x33);      /* Ensures display is in 8-bit mode */
  lcd_sending_command(0x32);        /* send for 4 bit initialization of LCD  */
  lcd_sending_command(0x28);          /* Use 2 line and initialize 5*7 matrix in (4-bit mode)*/
  lcd_sending_command(0x0f);          /* Display on, cursor on and blink cursor*/
  lcd_sending_command(0x01);          /* Clear display screen*/
  lcd_sending_command(0x06);          /* Clear display screen*/
  lcd_sending_command(0x02);          /* Clear display screen*/
  _delay_ms(2);

}


void lcd_display_string (char *str)       /* Send string to LCD function */
{
  int i;
  for(i=0;str[i]!=0;i++)        /* Send each char of string till the NULL */
  {
    lcd_sending_data (str[i]);
  }
}


int main()
{

  int i;
  lcd_initialization();             /* Initialization of LCD*/
  lcd_display_string("ECE2022");    /* Write string on 1st line of LCD*/
  lcd_sending_command(0xc0);            /* Go to 2nd line*/
  lcd_display_string("4-bit, by Louis WY LIU!");
  while(1) {
    for(i=0; i<16; i++) {_delay_ms(500); lcd_sending_command(0x18);}
    for(i=0; i<16; i++) {_delay_ms(500); lcd_sending_command(0x1c);}
  }

}