// MicroBoard program
// Control the speed of a 5-leads unipolar stepper motor (common +ve) by
// the SYSTEM and USER keys
// The 4 coil leads are connected to outputs 1~4 of ULN2003, which are
// controlled by Pins, 8~11, and the common lead is connected +6V

#define STEP   10	// speed! smaller the number the faster the rotation


main()
{
   int   i, speed;

   stop();
   speed = 10;
   writes("step", 500);
   loop {
      if(!pinstate(18)) if(speed >  10) speed -= STEP;
      if(!pinstate(19)) if(speed < 100) speed += STEP;
      writei('d', speed, 50);
      if(speed <= 0) { stop(); continue; }
      for(i=8; i <= 11; i++) {
        pinhigh(i);
        delay(speed);
        pinlow(i);
      }
   }
   writes("end", 2000);
}

stop()
{
   int   i;

   for(i=8; i <= 11; i++) pinlow(i);
}