How to display text on 16x2 LCD using AVR microcontroller (ATmega16)

Developed By: 

Akshay Daga

This article is in continuation to the article Single character LCD display using AVR. The aforesaid article shows how to display a single letter on LCD. Moving forward towards learning to work with LCD, this article explains how to display a string on LCD. Displaying string is occasionally used in many applications.

The connection of the LCD with the AVR microcontroller (ATmega16) is shown in the circuit diagram. A string is nothing but a sequence of characters. The following steps explain how to display a string on the LCD.

To send string on LCD:

        i.            Make a string pointer variable

       ii.            Pass the starting address of string to that pointer variable

      iii.            Pass the string pointer value to the LCD_write function

      iv.            Increment the pointer value and go to step (iii.) till the value of pointer reaches NULL character.

void LCD_write_string(unsigned char *str) //store address value of the string in pointer *str

{

int i=0;

while(str[i]!='\0') // loop will go on till the NULL character in the string 

{

LCD_write(str[i]); // sending data on LCD byte by byte

i++;

  }

return;

}

Circuit:

Code:

//Program to Display string on LCD using AVR Microcontroller (ATmega16)

/*

LCD DATA port----PORT B

signal port------PORT D

rs-------PD0

rw-------PD1

en-------PD2

*/

 

#include<avr/io.h>

#include<util/delay.h>

 

#define LCD_DATA PORTB //LCD data port

 

#define ctrl PORTD

#define en PD2 // enable signal

#define rw PD1 // read/write signal

#define rs PD0 // register select signal

 

void LCD_cmd(unsigned char cmd);

void init_LCD(void);

void LCD_write(unsigned char data);

 

int main()

{

DDRB=0xff;

DDRD=0x07;

init_LCD(); // initialization of LCD

_delay_ms(50); // delay of 50 mili seconds

LCD_write_string("EngineersGarage"); // function to print string on LCD

return 0;

}

 

void init_LCD(void)

{

LCD_cmd(0x38); // initialization of 16X2 LCD in 8bit mode

_delay_ms(1);

 

LCD_cmd(0x01); // clear LCD

_delay_ms(1);

 

LCD_cmd(0x0E); // cursor ON

_delay_ms(1);

 

LCD_cmd(0x80); // ---8 go to first line and --0 is for 0th position

_delay_ms(1);

return;

}

 

void LCD_cmd(unsigned char cmd)

{

LCD_DATA=cmd;

ctrl =(0<<rs)|(0<<rw)|(1<<en);

_delay_ms(1);

ctrl =(0<<rs)|(0<<rw)|(0<<en);

_delay_ms(50);

return;

}

 

void LCD_write(unsigned char data)

{

LCD_DATA= data;

ctrl = (1<<rs)|(0<<rw)|(1<<en);

_delay_ms(1);

ctrl = (1<<rs)|(0<<rw)|(0<<en);

_delay_ms(50);

return ;

}

 

void LCD_write_string(unsigned char *str) //store address value of the string in pointer *str

{

int i=0;

while(str[i]!='\0') // loop will go on till the NULL character in the string 

{

LCD_write(str[i]); // sending data on LCD byte by byte

i++;

  }

return;

}