int varPOS = 0;
//int varCAL = 7200;
int varCAL = 3600;

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600); // Must be 9600
  Serial.println("Hello Arduino\n");

 // put your main code here, to run repeatedly:
  Serial.println( "calibration " + String(varCAL/3600) + " steps per deg");

  varPOS = 0;
  Serial.println( "step " + String(varPOS) + ", angle " + getAngleString(varPOS) +"\n" );
  //varPOS = 0;
  moveAngle(-4003);
  Serial.println( "step " + String(varPOS) + ", angle " + getAngleString(varPOS) +"\n");
  //varPOS = 0;
  moveAngle(4005);
  Serial.println( "step " + String(varPOS) + "\n");
  varPOS = 0;
  moveToAngle(0);
  moveToAngle(1811);
  moveToAngle(1789);
  moveToAngle(-1811);
  moveToAngle(-1789);

}

void loop() {
  delay(1000);
}

int getStepFromAngle(int fAngle) {
  if (fAngle == 0) {
    return 0;
  }
  int fStep = round( ( fAngle / 3600.0 ) * varCAL );
  varPOS = varPOS % varCAL;
  if (varPOS < 0 ) {
    varPOS = varPOS + varCAL;
  }
  return fStep;
}

void moveAngle(int fAngle) {
  if (fAngle == 0) {
    return;
  }
  int fStep = getStepFromAngle(fAngle);
  varPOS = varPOS + fStep;
  // recalibrate into positive values
  varPOS = varPOS % varCAL;
  if (varPOS < 0 ) {
    varPOS = varPOS + varCAL;
  }
  return;
}

void moveToAngle(int fToAngle) {
  int fStep = getStepFromAngle(fToAngle);
  int fDiff = fStep - varPOS;
  if (fDiff >  varCAL/2) { fDiff = fDiff - varCAL; }
  if (fDiff < -varCAL/2) { fDiff = fDiff + varCAL; }
  moveAngle(fDiff);
  Serial.println( "moved " + String(fDiff) + ", to " + String(varPOS));
  return;
}

int getAngleFromStep(int fStep) {
  if (fStep == 0) {
    return 0;
  }
  int fAngle = round( ( fStep * 3600.0 ) / varCAL );
  // subtract multiples of full circle
  fAngle = fAngle % 3600;
  if (fAngle < 0 ) {
    fAngle = fAngle + 3600;
  }
  return fAngle;
}

String getAngleReal(int fAngle) {
  //Serial.println( String( getAngleFromStep(fAngle)/10.0 ) +" --- \n");
  return String( getAngleFromStep(fAngle)/10.0, 1);
}