receive message "controller receive data while busy" in Proteus.

#include<reg51.h>
/* function declaration start */
void delay(int);
void initlcd(void);						 
void w_cmd(int);
void w_data(char);
void Rotate(void);
void op_a(int);
void op_b(int);
/* function declaration stop */

/* pin declaration start */ 
sbit l = P3^5;		// pin declaration for sensors
sbit m = P3^6;
sbit r = P3^7;
sbit rs = P1^2;	   // pin declaration for lcd
sbit en = P1^1;
sbit sw1 = P1^0;   // pin declaration for switch
sbit out = P1^5;   // pin declaration for output to another uc

/*function definatio start */

 void delay(int c)		// function for delay
{
 int i,j;
 for(i=0;i<c;i++)
 for(j=0;j<100;j++);	 
} 

void initlcd(void)	  // function for initializing the lcd
 {
  w_cmd(0x38);
  delay(50);
  w_cmd(0x0c);
  delay(50);
  w_cmd(0x01);
  delay(50);
  w_cmd(0x06);
  delay(50);
 }

void w_cmd(int z)	// function for sending command to lcd
{
   rs = 0;           
   P2 = z;             
   en = 1;             
   delay(1);
   en  = 0;             
   delay(1);
}

void w_data(char y)	   // function for sending data  to lcd
{
   rs = 1;             
   P2 = y;             
   en  = 1;             
   delay(1);
   en  = 0;             
   delay(1);
}

lcd_data(unsigned char *disp)  // function for sending string to lcd
{
 int x;
 for(x=0;disp[x]!=0;x++)
 {
  w_data(disp[x]);
 }
}
							 
void Return(void)	  // function for returning the cursor at home positon
{
 w_cmd(0x01);
 delay(2);
 w_cmd(0x80);
 delay(2);
}

void Return2(void)   //	 function for move cursor at second line
{
 w_cmd(0xc0);
 delay(2);
}

void Rotate(void)	// function for measurement of rotation
   {
    int a,b;
     while(l==0&&r==0);		// check the status of left and right sensor
     while(l==1)				
     {
      b=0;
	  while(l==1);
	  while(l==0);
      while(m==0)	  // start measurement when left sensor sense beam second time
      {
       delay(1);
       b=b+1;
      }
	  while(r==0)
	  {
	   delay(1);
	   b=b+1;
	  }
      op_b(b);
     }
   
     while(r==1)
     {
      a=0;
	  while(r==1);
	  while(r==0);
      while(m==0)		// start measurement when right sensor sense beam second time
      {
       delay(1);
       a=a+1;
      }
	  while(l==0)
	  {
	   delay(1);
	   a=a+1;
	  }
      op_a(a);
     }
    }


void op_b(int h)			// function for calculation the rotation from left to right
{
   int f,d4,d5,d6,r2,r4;
   f=90000/h;			   // conveting into degree per second
   d4=f/100;
   if(d4>=1)
   {
   	out=0;
   }			   // saperating the digits for ASCII conversion 
   r2=f%100;
   d5=r2/10;
   r4=r2%10;
   d6=r4%10;
   d4=d4+48;			  // converting from decimal to ASCII
   d5=d5+48;
   d6=d6+48;
    Return();
   	w_data(d4);
	w_data(d5);
	w_data(d6);
	Rotate();
}

void op_a(int g)	 // function for calculation the rotation from left to right
{
   int e,d1,d2,d3,r1,r3;
   e=90000/g;
   d1=e/100;
   if(d1>=1)
   {
   	out=0;
   }
   r1=e%100;
   d2=r1/10;
   r3=r1%10;
   d3=r3%10;
   d1=d1+48;
   d2=d2+48;
   d3=d3+48;
  	Return();
   	w_data(d1);
	w_data(d2);
	w_data(d3);
	Rotate();
}

void main()		// start main program
{
 P1=0xff;	   // set the port 1 as input 
 sw1=1;		   // set the switch as input
 initlcd();
 w_cmd(0x80);
 delay(1);
 lcd_data("   WELL-COME");
 delay(1000);
 w_cmd(0x01);
 delay(1);

  while(m==0)
 {
  lcd_data("please set your");
  Return2();
  lcd_data("head at middle  ");
  delay(100);
  
  while(m==1)
  {
   Return();
   lcd_data("start rotation  ");
   delay(100);
  
   while(1)
   {
   Rotate();
   }
  }
 }
}