Tutorial for Scroll text on 16x2 LCD with 8051 Microcontroller in c

In our last tutorial we interface 2x16 LCD with 8051 in assembly, now lets display some scrolling text on LCD. it is very useful because generally we have a long text to display and a 2x16 LCD display only 16 character at a time.

if you don't know about LCD interfacing and  how it is display character on different address then plz read my last tutorial in which  i talk about LCD in detail.

LCD interfacing with 8051 microcontroller in assembly

i use keil to compile my code and simulate it in multisim (my fav.). you can you any simulator with hex file  but code is written in keil so c program file may not run in other compiler.

the concept here i use is that after writting 16 character to LCD i move my text to the left side one character at a time and then write next character.

command 18h is used to move text left ( if don't know please read last tutorial )

i connect my data line of LCD to port P1 and 3 control lines to port P2. as

RW-to pin P2.0

RS- to pin P2.1

EN-to pin P2.2 // change according your design 

as our last tutorial LCD interfacing with 8051 we need to subrouting ( functions ) also in C to send command and data.

command sending function:

//..............cmd.......................

void lcd_cmd(unsigned char cmd){

 

rs=0;           // rs is low means we are sending command to LCD

P1=cmd;

en=1;

delay(1);

en=0;

}

//here cmd is variable which get value command and pass to port P1, and rs, en are the command pins.

data sending function:

//............data...........................

void lcd_display(unsigned char text){

        rs=1;       //high means we are sending text to display on LCD  

P1=text;

en=1;

delay(1);

en=0;

}

now we need to initialize to LCD to get required result like cursor on/off, cursor moving direction etc..

LCD initialization:

//................init...................

void lcd_init(void ){

 

lcd_cmd(0x30); //selecting 8 bit mode, single line, and 5x7 font read more

lcd_cmd(0x0c); //for display on,cursor off and  blinking also off

lcd_cmd(0x06);//cursor position auto increment and move cursor to right

}

some code to clear LCD

//............clear..............

void lcd_clear(void){

   lcd_cmd(0x01);

}

now the main part of tutorial to scroll text.

//.............main...............

void main(void ){

unsigned char i,loc=0x80;

rw=0;                                             //we are writing to LCD 

lcd_clear();                           //clear

lcd_init();                          //initialize LCD

        for(i=0;text[i]!='\0';i++){  //reading  array character by charcter

loc++;                                                   // increment LCD address by one   

lcd_display(text[i]);              //sending text to display on port 

if(loc>=0x8f)   // this is the logic that we move text to left side after we reached at 

lcd_cmd(0x18);  // location 8fh which is last address on lcd in  first line

}

 

}

the whole program are like this

//..........................................LCD scrolling.............................................................

#include<REGX51.H>

#define rw P2_0  //read write pin

#define rs P2_1  // data/command pin

#define en P2_2 //enable pin

void lcd_init(void );

void lcd_cmd(unsigned char );

void delay(unsigned int );

void lcd_display(unsigned char);

void lcd_clear(void );

const unsigned char text[]={"electronets.blogspot.com | scrolling test on LCD  "}; 

void main(void ){

unsigned char i,loc=0x80;

rw=0;

lcd_clear();

lcd_init();

for(i=0;text[i]!='\0';i++){

loc++;

lcd_display(text[i]);

if(loc>=0x8f)

lcd_cmd(0x18);

}

 

}

void lcd_clear(void){

  

  lcd_cmd(0x01);

}

void lcd_init(void ){

 

lcd_cmd(0x30);

lcd_cmd(0x0c);

lcd_cmd(0x06);

}

void lcd_cmd(unsigned char cmd){

 

rs=0;

P1=cmd;

en=1;

delay(1);

en=0;

}

void lcd_display(unsigned char text){

rs=1;

P1=text;

en=1;

delay(1);

en=0;

} 

void delay(unsigned int time){

unsigned int i,j;

for (i=0;i<time;i++)

for(j=0;j<1275;j++); 

}

this is the our scrolling LCD, i hide .c , .hex file and multisim simulation file behind this image. to get files download image and rename it to a ".rar" file or open it with winRaR.

click to zoom

 thanx for  comming and please share it if you like this .......