How to interface 16x2 LCD with AVR microcontroller (ATmega16)

Summary

LCD is used to present textual information to the users. It is great fun to work with LCD. Also LCD makes your application more interactive. LCD comes in various configurations and the most popular one is 16x2 matrix display. This article shows the interfacing of ATmega16 with LCD by displaying a simple character on the LCD. For more information about LCD, refer the article LCD interfacing.
 
Interface LCD | Interfacing LCD with AVR Microcontroller (Atmega16)

Description

 
In this project LCD is working in 8-bit mode i.e., the data transferred to the LCD must be in 8-bit data form. The PortA of ATmega16 is connected to data pins of LCD and is defined as LCD_DATA. PortB is defined as control pins (Rs, R/W and En).

Conceptually, interfacing LCD with AVR microcontroller is similar to that of interfacing it with any other microcontroller.
The following steps explain in detail how LCD can be interfaced with ATMEGA 16:

Step1: To initialize LCD
The following instructions are used to initialize LCD.
·       0x38 to initialize LCD in 8-bit mode
·       0x01 to clear LCD
·       0x0E to make cursor ON
·       0x80 to go to first line and 0th position in LCD
 Delay of around 50 micro second is necessary b/w two commands for execution of instructions. 
 
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;
}
Step2: Define command function
To send any command to LCD
·         Transfer the command to LCD_DATA port
·         Set RS and RW bit to go LOW and enable as HIGH
·         Give a small delay
·         Set enable to LOW 
 
void LCD_cmd(unsigned char cmd)
{
	LCD_DATA=cmd;
	ctrl =(0<<rs)|(0<<rw)|(1<<en);	// RS and RW as LOW and EN as HIGH
	_delay_ms(1);
	ctrl =(0<<rs)|(0<<rw)|(0<<en);	// RS, RW , LOW and EN as LOW
	_delay_ms(50);
	return;
}
 
Step3: Define write function
To display any data on LCD
·         Transfer the data (Ascii value of the character to be sent) to LCD_DATA port.
·         Make RW as LOW and set RS and enable as HIGH.
·         Give a small delay.
·         Make enable pin LOW

 

void LCD_write(unsigned char data)
{
	LCD_DATA= data;
	ctrl = (1<<rs)|(0<<rw)|(1<<en);	// RW as LOW and RS, EN as HIGH
	_delay_ms(1);
	ctrl = (1<<rs)|(0<<rw)|(0<<en);	// EN and RW as LOW and RS HIGH
	_delay_ms(50);			// delay to get things executed
	return ;
}

 

Circuit Diagram

Video

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