/* * STEPPER.C * sweeping stepper's rotor cw and cww 400 steps * Copyright (c) 1999 by W.Sirichote */#include c:\mc51\8051io.h  /* include i/o header file */#include c:\mc51\8051reg.hregister unsigned char j,flag1,temp;register unsigned int cw_n,ccw_n;unsigned char step[8]={0x80,0xc0,0x40,0x60,0x20,0x30,0x10,0x90}#define n 400/* flag1 mask byte   0x01  run cw()   0x02  run ccw()*/main(){  flag1=0;  serinit(9600);  disable();  /* no need timer interrupt */  cw_n = n;    /* initial step number for cw */  flag1 |=0x01; /* initial enable cw() */ while(1){    {    tick_wait();  /* wait for 10ms elapsed */    energize();   /* round-robin execution the following tasks every 10ms */    cw();    ccw();  }        }}cw(){       if((flag1&0x01)!=0)       {        cw_n--;       /* decrement cw step number */        if (cw_n !=0)         j++;         /* if not zero increment index j */         else         {flag1&=~0x01; /* disable cw() execution */          ccw_n = n;    /* reload step number to ccw counter */          flag1 |=0x02; /* enable cww() execution */          }       }         }ccw(){       if((flag1&0x02)!=0)       {        ccw_n--;       /* decremnet ccw step number */        if (ccw_n !=0)         j--;          /* if not zero decrement index j */         else         {flag1&=~0x02; /* disable ccw() executon */          cw_n = n;     /* reload step number to cw counter */          flag1 |=0x01; /* enable cw() execution */          }       }         }tick_wait(){   /* cputick was replaced by simpler ASM code 10ms wait */    asm" JNB TCON.5,*";   /* wait for TF0 set */    asm" CLR TCON.5";     /* clear TF0 for further set */    asm" ORL TH0,#$DC";   /* reload TH0 with $DC, TL0 = 0 */}energize(){    P1 = step[(j&0x07)];  /* only step 0-7 needed */}