This document contains C code for initializing and controlling a 16x2 LCD display module connected to an AVR microcontroller. It defines macros for the LCD port and data direction register. Functions are defined to send command and data bytes to the LCD via the LCD port. An lcd_init() function initializes the LCD to 4-bit mode and clears the display. Other functions allow setting the cursor position, writing a string to the LCD, and clearing the display. The main() function demonstrates initializing the LCD, writing strings to different lines, waiting, and then clearing the display.

1. #include<avr/io.h> //include avr header file
#include<util/delay.h> //include delay header file
#define LCD_PRT PORTC // define portb as a lcd port
#define LCD_DDR DDRC //define ddr for lcd
/*#define LCD_PIN PINB
#define LCD_RS 0
#define LCD_RW 1
#define LCD_EN 2*/
void lcdcommand( unsigned char cmnd )
{
//to send higher bit of cmnd to LCD_PRT
LCD_PRT=(LCD_PRT & 0X0F) | (cmnd & 0XF0); //masking of portb in nibbles
LCD_PRT = (LCD_PRT&0b11111100); //FOR MAKING RS=0, RW=0
LCD_PRT = (LCD_PRT|0b00000100); //FOR MAKING EN=1
_delay_us(100);
LCD_PRT = (LCD_PRT&0b11111011); //FOR MAKING EN=0
_delay_us(500);
//to send lower bit of cmd to LCD_PRT
LCD_PRT=(LCD_PRT & 0X0F) | (cmnd << 4);
LCD_PRT = (LCD_PRT|0b00000100);/*FOR MAKING EN=1*/
_delay_us(100);
LCD_PRT = (LCD_PRT&0b11111011);/*FOR MAKING EN=0*/
_delay_us(500);
}
void lcddata( unsigned char data ) //Function to send data to LCD
{
LCD_PRT = (LCD_PRT & 0x0F) | (data & 0xF0); //to send higher bit of cmnd to
LCD_PRT
LCD_PRT = (LCD_PRT|0b00000001); /*FOR MAKING RS=1*/
LCD_PRT = (LCD_PRT&0b11111101); /*FOR MAKING RW=0*/
LCD_PRT = (LCD_PRT|0b00000100); /*FOR MAKING EN=1*/
_delay_us(100);
LCD_PRT = (LCD_PRT&0b11111011); /*FOR MAKING EN=0*/
_delay_us(500);
LCD_PRT = (LCD_PRT & 0x0F)|(data<<4); //to send lower bit of data to
LCD_PRT
LCD_PRT = (LCD_PRT|0b00000100); /*FOR MAKING EN=1*/
_delay_us(100);
LCD_PRT = (LCD_PRT&0b11111011); /*FOR MAKING EN=0*/
_delay_us(500);
}
void lcd_init() //Function to initialize the LCD
{
LCD_DDR=0xFF; //LCD port as output port

2. LCD_PRT = (LCD_PRT&0b11111011); //FOR MAKING EN=0
lcdcommand(0x33);
_delay_us(1000);
lcdcommand(0x32);
_delay_us(1000);
lcdcommand(0x28); //these three command are for 4 bit LCD
mode
_delay_us(1000);
lcdcommand(0x0E); //display on cursor on
_delay_us(1000);
lcdcommand(0x01); //to clear display
_delay_us(1000);
lcdcommand(0x06); //shift the cursor to right
_delay_us(1000);
}
void lcd_gotoxy(unsigned char x,unsigned char y) // Function to set a
starting position on 16x2 LCD
{
unsigned char firstcharadr[]={ 0x80, 0xC0};
lcdcommand(firstcharadr [y-1]+x-1);
_delay_us(2000);
}
void lcd_puts(char *str) // Function to send a string to LCD
{
unsigned char i=0;
while(str[i]!=0)
{
lcddata(str[i]);
_delay_ms(1000);
i++;
}
}
void lcd_clr(void) // Function to clear the lcd
{
lcdcommand(0x01);
_delay_ms(2000);
}
int main(void)
{
lcd_init();
while(1)
{
lcd_gotoxy(1,1);
lcd_puts("E&C");

3. _delay_ms(2000);
_delay_ms(100);
lcd_gotoxy(1,2);
lcd_puts("SRMSCET");
_delay_ms(9000);
lcd_clr();
}
}