Scrolling Any one Row of a 16X2 LCD Display

        Since there is no predefined libraries to rotate a single row of an LCD we need to do it with our own functions. 

        I have written such function using this function u can

• Rotate any of the two row
• Rotate left or right

A sample program and its header file is given below 

 #include<lcd.h>

void main()

{

char *r1="LCD ROW ONE";

char *r2="LCD ROW TWO";

init_8bit();

hide_cursor;

string_8bit(r1);

xy_8bit(1,1);

string_8bit(r2);

clear_8bit(0,0);                //clear_8bit(row,column)

delay(100);

 while(1)

 {

  rotate(r2,1,'r'); //rotate("string",which row(0,1),which dir('r' ||'l'))

 }

}

The Source code requires  <lcd.h>  header file  which is defined below

#include<reg51.h>

#include<string.h>

#define hide_cursor cmd_8bit(0x0c)

#define interface_8bit

sbit RS=P3^3;

sbit RW=P3^4;

sbit EN=P3^5;

sfr lcdport=0x90;

void cmd_8bit(unsigned char);

void disp_8bit(unsigned char);

void xy_8bit(unsigned char,unsigned char);

void clear_8bit(unsigned char,unsigned char);

void rotate(char *,unsigned char ,unsigned char );

void rotate_right(char *,unsigned char);

void rotate_left(char *,unsigned char);

void cmd_4bit(unsigned char);

void disp_4bit(unsigned char);

void xy_4bit(unsigned char,unsigned char);

void delay(unsigned char);

void init_8bit();

void init_4bit();

void string_8bit(char *);

#ifdef interface_8bit

void cmd_8bit(unsigned char c)

{

lcdport=c;

RS=0;

RW=0;

EN=1;

delay(1);

EN=0;

}

void disp_8bit(unsigned char d)

{

lcdport=d;

RS=1;

RW=0;

EN=1;

delay(1);

EN=0;

}

void string_8bit(char *s)

{

while(*s!='\0')

{

disp_8bit(*s);

s++;

}

}

void init_8bit()

{

cmd_8bit(0x38);

cmd_8bit(0x0e);

cmd_8bit(0x80);

cmd_8bit(0x06);

cmd_8bit(0x01);

}

void xy_8bit(unsigned char r,unsigned char c)

{

if(r==0)

cmd_8bit(0x80+r);

else

cmd_8bit(0xc0+c);

}

 void clear_8bit(unsigned char r,unsigned char c)

 {

   if(r)

   {

   cmd_8bit(0x80+(r-1));

   disp_8bit(' ');

   }

   if(c)

   {

   cmd_8bit(0xc0+(c-1));

   disp_8bit(' ');

   }

 }

  void rotate(char *s,unsigned char r,unsigned char dir)

  {

  unsigned char row;

  char *space="                ";

  char result_string[50];

  strcpy(result_string,space);

  strcat(result_string,s);

  strcat(result_string,space);

  if(r==0)

  row=0x80;

  else

  row=0xc0;

  if(dir=='r')

  rotate_right(result_string,row);

  else

  rotate_left(result_string,row);

  }

  void rotate_right(char *s,unsigned char row)

  {

  int i;

   for(i=0;i<(strlen(s)+1);i++)

 {

  cmd_8bit(row);

  string_8bit(s+i);

  delay(1);

  }

  }

  void rotate_left(char *s,unsigned char row)

  {

  int i;

   for(i=0;i<(strlen(s)+1);i++)

 {

  cmd_8bit(row);

  string_8bit(s+strlen(s)-i);

  delay(1);

  }

  }

 #else

void init_4bit()

{

cmd_4bit(0x02);

cmd_4bit(0x28);

cmd_4bit(0x0E);

cmd_4bit(0x80);

cmd_4bit(0x06);

}

void cmd_4bit(unsigned char c)

{

RS=0;

lcdport=(c&0xf0);

EN=1;

delay(100);

EN=0;

lcdport=(c&0x0f)<<4;

EN=1;

delay(100);

EN=0;

}

void disp_4bit(unsigned char d)

{

RS=1;

lcdport=d&0xF0;

EN=1;

delay(100);

EN=0;

lcdport=(d&0x0F)<<4;

EN=1;

delay(100);

EN=0;

}

void string_4bit(char *s)

{

RS=1;

while(*s!='\0')

{

disp_4bit(*s);

s++;

}

}

void xy_4bit(unsigned char r,unsigned char c)

{

if(r==0)

cmd_4bit(0x80+c);

else

cmd_4bit(0xc0+c);

}

#endif

void delay(unsigned char d)

{

int i;

TMOD=0x01;

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

{

TH0=0xee;

TL0=0x00;

TR0=1;

while(TF0==0);

TR0=0;

TF0=0;

 }

}

     If there is any updation with my code please let me know

through your comments