How to display text on 16x2 LCD using AVR microcontroller (ATmega16)- (Part 8/46)

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]!=’’) // loop will go on till the NULL character in the string

{

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

i++;

}

return;

}

Project Source Code

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//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]!='') // loop will go on till the NULL character in the string 
{
LCD_write(str[i]); // sending data on LCD byte by byte
i++;
  }
return;
}
 
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