Trying to move a stepper motor back and forth

Question

So, I am trying to move a stepper motor through a halfway revolution (1024 steps), and once that is completed, have it move back and forth by about 100 steps in either direction.

I am having some trouble with this though, because while it will move in one direction, it will not move in the other.

void setup()
{ 
    stepper1.setMaxSpeed(1000);
    stepper1.moveTo(1024);
    stepper1.setAcceleration(100);
    Serial.begin(19200);
    while(!Serial);
}

void loop()
{
    stepper1.run();
    static int ctr = 0; //counter value to store how many times the back and forth motion has occured
    if(stepper1.currentPosition() == 1024){
      backMotion(stepper1.currentPosition());
      forthMotion(stepper1.currentPosition());
      ctr++;
    }
//    if(stepper1.currentPosition() == 824 && ctr > 0 && ctr < 30){
//      forthMotion(stepper1.currentPosition());
//    }
}  

void backMotion(int value){
    int current = value;
    int back_distance = current - 200; //distance to move back by
    stepper1.moveTo(back_distance);
}

void forthMotion(int value) {
  int current = value;
  int forth_distance = current+200;
  stepper1.moveTo(forth_distance);
}

So, when I call the forthMotion function right after the backMotion function, it will just move forward. Which makes no sense to me. Shouldn't it be moving backwards, and then forwards in an infinite loop? Because it will hit 1024, go back to 824, hit 1024 again, and so on and on...

Also, when I call the backMotion function, isn't the Arduino code supposed to be blocking in that, nothing else gets executed while that is running?

Edit: The code seems to work when I uncomment the if statement in the loop function.

Answer 1

I guess the solution might be this:

in back motion

void backMotion(){

    int back_distance = - 200; //distance to move back by
    stepper1.moveTo(back_distance);
}

In forward motion

void forthMotion() {
  
  int forth_distance = 200;
  stepper1.moveTo(forth_distance);
}

In loop

void loop()
{
    stepper1.run();
    static int ctr = 0; //counter value to store how many times the back and forth motion has occured

    stepper1.moveTo(1024);
    while(ctr < 30){

      backMotion();
      delay(500);

      forthMotion();
      delay(500);
      ctr++;
    }
//    if(stepper1.currentPosition() == 824 && ctr > 0 && ctr < 30){
//      forthMotion(stepper1.currentPosition());
//    }
}  

Your main code will be like this

void setup()
{ 
    stepper1.setMaxSpeed(1000);
    stepper1.moveTo(1024);
    delay(3000); // wait till stepper gets to destination
    stepper1.setAcceleration(100);
    Serial.begin(19200);
    while(!Serial);
}

void loop()
{
    stepper1.run();
    static int ctr = 0; //counter value to store how many times the back and forth motion has occured

    while(ctr < 30){

      backMotion();
      delay(500);

      forthMotion();
      delay(500);
      ctr++;
    }
//    if(stepper1.currentPosition() == 824 && ctr > 0 && ctr < 30){
//      forthMotion(stepper1.currentPosition());
//    }
}  


void backMotion(){

    int back_distance = - 200; //distance to move back by
    stepper1.moveTo(back_distance);
}


void forthMotion() {
  
  int forth_distance = 200;
  stepper1.moveTo(forth_distance);
}

Answer 2

Steppers don't typically have feedback about their position (as opposed to servos). Normally you're just telling a stepper how much and how quickly to rotate. As opposed to servos, which you tell which position to rotate to.

Are you sure you're using a stepper?