How to interface LCD in 4 bit mode with AVR microcontroller

This article explains interfacing of LCD with ATmega8 using 4-bit mode. In this mode only four pins are used for sending data and command instructions. This mode has the advantage over the 8-bit mode as it uses less number of pins. The remaining pins of the controller are available for normal use


LCD Pin Description :

Pin No	Symbol	I/O	Description
1	Vss	-	Ground
2	Vcc		+5V
3	Vee		Contrast Control
4	RS	Input	Command/Data Register
5	R/W	Input	Read/Write Register
6	E	Input/Output	Enable
7	DB0	Input/Output	Not Used in 4-Bit Mode
8	DB1	Input/Output	Not Used in 4-Bit Mode
9	DB2	Input/Output	Not Used in 4-Bit Mode
10	DB3	Input/Output	Not Used in 4-Bit Mode
11	DB4	Input/Output	Data Bus in 4-Bit Mode
12	DB5	Input/Output	Data Bus in 4-Bit Mode
13	DB6	Input/Output	Data Bus in 4-Bit Mode
14	DB7	Input/Output	Data Bus in 4-Bit Mode
15	Vcc	-	For LCD Back Light
16	Vss	-	For LCD Back Light

FLOW CHART :

LCD in 4 bit mode with AVR

Simulation by Proteus .

Program:

#include <avr/io.h>

#include <util/delay.h>

#include "lcd.c"

int main()

{

unsigned char i;

//Initialize LCD module

LCDInit(LS_BLINK|LS_ULINE);

//Clear the screen

LCDClear();

//Simple string printing

LCDWriteString("Congrats ");

//A string on line 2

LCDWriteStringXY(0,1,"Loading ");

//Print some numbers

for (i=0;i<99;i+=1)

{

LCDWriteIntXY(9,1,i,3);

LCDWriteStringXY(12,1,"% ");

_delay_loop_2(0);

_delay_loop_2(0);

_delay_loop_2(0);

_delay_loop_2(0);

}

//Clear the screen

LCDClear();

//Some more text

LCDWriteString("Hello world");

LCDWriteStringXY(0,1,"By YourName Here");    // <--- Write ur NAME HERE !!!!!!!!!!!

//Wait

for(i=0;i<100;i++) _delay_loop_2(0);

//Some More ......

LCDClear();

LCDWriteString("  kannupandiyan");

LCDWriteStringXY(0,1," webs.com");

//Wait

for(i=0;i<100;i++) _delay_loop_2(0);

//Custom Chars ......

LCDClear();

LCDWriteString("Custom Char !!!");

LCDWriteStringXY(0,1,"%0%1%2%3 %4%5%6%7");

return 0;

}

DOWNLOAD THE CODE HERE : click here to download

* Note: The code tested in hardware also ., it work's perfectly 100% sure 

if u have any problem ., inform me ....