~: Stepper motor driver program :~

#include <reg51.h>
#include <string.h>

sbit rs = P3^0;     // rs pin of LCD
sbit en = P3^1;     // en pin of LCD
sbit led1 = P3^7;
sbit led2 = P3^6;
sbit led3 = P3^5;
sbit led4 = P3^4;
sbit led5 = P3^3;
sbit b = P2^7;     // busy flag
sbit dir = P0^0;    // direction flag
int digit[2];     // 2 digit number

void writecmd(unsigned char a); // function initializations
void writedata(unsigned char b);
void lcdbusy(void);
void writestr(unsigned char *s);

void delay(int d1)    // variable delay to change RPM
  {
    int k;
 TL0 = 0x17;
 TH0 = 0xFC;
 TR0 = 1;
 for(k=0;k<d1;k++)
   {
  while(TF0==0);
  TF0 = 0;
  TL0 = 0x17;
  TH0 = 0xFC;
   }
 TR0 = 0;
  }
void display(unsigned int z)   // display decimal digit on LCD
  {
   int z1,ASCII[2];    
 z1=z%10;
 ASCII[1]=z1+0x30;
 z=z/10;
 ASCII[0]=z+0x30; 
 writedata(ASCII[0]);
 writedata(ASCII[1]); 
  }
void writecmd(unsigned char a)
{
 lcdbusy();
 rs = 0;
 //rw = 0;
 P2 = a; 
 en = 1;
 en = 0;
}
void writedata(unsigned char b)
{
 lcdbusy();
 rs = 1;
 //rw = 0;
 P2 = b; 
 en = 1;
 en = 0; 
}
void lcdbusy()
{
 int g;
 for(g=0;g<1500;g++);
}
void writestr(unsigned char *s)
{
 unsigned int l,m;
 l = strlen(s);
 for(m=0;m<l;m++)
 {
  writedata(*s);
  s++;  
 }
}
keydly()
  {
    int x,y;
 for(x=0;x<100;x++)
   for(y=0;y<1000;y++);
   }
void main()
  {
 int t=0,i=0,j,f,d,p=0,q=0;
 unsigned int p2,p1;
 P3=0x00;         // initilize i/o ports
 P2=0x00;
 TMOD = 0x01;        // T0 as 16 bit timer 
 writecmd(0x3C);        // initilize LCD
 writecmd(0x0E);
back:f=0;
 writecmd(0x01);
 if(p==0) writestr("enter rotations");  // display message enter rotation
 else
   {
    writestr("enter RPS");     // 2nd time display enter RPS
      p=0;
   }
 writecmd(0xC0);
 writestr("in 2 digits:");  
loop:P1=0xF0;         // rows as output and columns as input
 while(P1==0xF0);       // wait until any key press 
 while(P1!=0xF0)
   {
     P1=0xFE;        // when key is pressed start scanning
     if(P1==0xEE)       // if enter is pressed
    {
   if(q==0)       // 1st time calculate 
     {
    p1=digit[0]*10+digit[1];  // rotations
    q=1;
    p=1;
    f=1;
     }
   else
     {
    p2=digit[0]*10+digit[1];  // 2nd time calculate        
    d=50/p2;      // RPM and required delay
    writecmd(0x01);
    writestr("press start");  // display message press start
     }  
   t=1;
   i=0;
    }
  else if(P1==0xDE){writedata(0x30);digit[i]=0;t=1;i++;} // for digit 0 display 0 and store 0 in 'digit'
  else if(P1==0xBE)      // for enter key         
    {
     writecmd(0x80);      // first display  
   writestr("rotations: ");   // rotations
   display(p1);
   writestr("   ");
   writecmd(0xC0);   
   writestr("RPS: ");     // and RPS
   display(p2);
   writestr("          ");
   p1*=5;        // calculate required no of pulses  
   if(dir==0)       // depending upon direction switch      
     {
    for(j=0;j<p1;j++)    // rotate CW
        {
       P3=0x18;
     delay(d);
     P3=0x28;
     delay(d);
     P3=0x40;
     delay(d);
     P3=0x80;
     delay(d);
        }
     }
   else
     {
    for(j=0;j<p1;j++)    // or CCW
        {
       P3=0x14;
     delay(d);
     P3=0x84;
     delay(d);
     P3=0x40;
     delay(d);
     P3=0x20;
     delay(d);
       }
     }
   P3=0x00;
   f=1;
   t=1;   
   q=0;
   }
  if(t==1) break;          // if key is pressed get out of loop
  P1=0xFD;
  if(P1==0xED) {writedata(0x37);t=1;digit[i]=7;i++;} // for digit 7 display 7 and store 7 in 'digit'
  else if(P1==0xDD) {writedata(0x38);t=1;digit[i]=8;i++;} // same for all digits
  else if(P1==0xBD) {writedata(0x39);t=1;digit[i]=9;i++;}  

  if(t==1) break;
  P1=0xFB;
  if(P1==0xEB){writedata(0x34);t=1;digit[i]=4;i++;}
  else if(P1==0xDB) {writedata(0x35);t=1;digit[i]=5;i++;}
  else if(P1==0xBB) {writedata(0x36);t=1;digit[i]=6;i++;}  

  if(t==1) break;
  P1=0xF7;
  if(P1==0xE7){writedata(0x31);digit[i]=1;t=1;i++;}    
  else if(P1==0xD7) {writedata(0x32);t=1;digit[i]=2;i++;}
  else if(P1==0xB7) {writedata(0x33);t=1;digit[i]=3;i++;}
  
  if(t==1) break;
  }
   keydly();             // key debounce delay  
   t=0;             // reset key press flag
   if(f==0) goto loop;         // return back to loop
   else goto back;  
  }