Accelstepper homing with AttachInterrupt

//If you found my video helpful, please SUBSCRIBE:  https://www.youtube.com/channel/UCKp1MzuAceJnDqAvsZl_46g
//The code belongs to this tutorial video: https://youtu.be/0Xi7unlq1L4
//The tutorial video for the AccelStepper library: https://youtu.be/AR0un3kg-iM

//linear carriage:
/* c goes away from the motor
 * s or o goes towards the motor
 * h does homing, based on the default direction
 * max range is 4000 steps = 10 rotations = 200 mm = 20 cm
*/

/*
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*/

#include <AccelStepper.h>

long receivedMMdistance = 0; //distance in mm from the computer
long receivedDelay = 0; //delay between two steps, received from the computer
long receivedAcceleration = 0; //acceleration value from computer
char receivedCommand; //character for commands
/* s = Start (CCW) // needs steps and speed values
 * o = open (CCW) // needs steps and speed values
 * c = close (CW) //needs steps and speed values
 * a = set acceleration // needs acceleration value
 * h = homing // goes back slowly to the origin. Origin should be determined manually as well as all the parameters! (speed, dir, acc...etc)
 * n = stop right now! // just the 'n' is needed
 */

bool newData, runallowed = false; // booleans for new data from serial, and runallowed flag

const byte ledPin = 4; //led status pin, just to get a visual feedback from the button
const byte interruptPin = 2; //pin for the microswitch using attachInterrupt();

// direction Digital 9 (CCW), pulses Digital 8 (CLK)
AccelStepper stepper(1, 8, 9);




void setup()
{
  pinMode(interruptPin, INPUT_PULLUP); // internal pullup resistor (debouncing)
  attachInterrupt(digitalPinToInterrupt(interruptPin), stopMotor, FALLING);
  //If you choose FALLING, make sure that the switch connects the pin 2 to the GND when it is pressed.
 //You can change FALLING but make sure that you connect the switch to GND or +5V accordingly!

//LED pins, OFF by default
  pinMode(ledPin, OUTPUT);
  digitalWrite(ledPin,LOW);

  Serial.begin(9600); //define baud rate
  Serial.println("Testing Accelstepper"); //print a message

  //setting up some default values for maximum speed and maximum acceleration
  stepper.setMaxSpeed(2000); //SPEED = Steps / second
  stepper.setAcceleration(1000); //ACCELERATION = Steps /(second)^2
  stepper.disableOutputs(); //disable outputs, so the motor is not getting warm (no current)


}

void loop()
{

  checkSerial(); //check serial port for new commands

  continuousRun2(); //method to handle the motor

}


void continuousRun2() //method for the motor
{
  if (runallowed == true)
  {
    if (abs(stepper.currentPosition()) < receivedMMdistance) //abs() is needed because of the '<'
    {
      stepper.enableOutputs(); //enable pins
      stepper.run(); //step the motor (this will step the motor by 1 step at each loop)
    }
    else //program enters this part if the required distance is completed
    {

      runallowed = false; //disable running -> the program will not try to enter this if-else anymore
      stepper.disableOutputs(); // disable power
      Serial.print("POS: ");
      Serial.println(stepper.currentPosition()); // print pos -> this will show you the latest relative number of steps
      stepper.setCurrentPosition(0); //reset the position to zero
      Serial.print("POS: ");
      Serial.println(stepper.currentPosition()); // print pos -> this will show you the latest relative number of steps; we check here if it is zero for real
    }


  }
  else //program enters this part if the runallowed is FALSE, we do not do anything
  {
    return;

  }
}

void checkSerial() //method for receiving the commands
{
  //switch-case would also work, and maybe more elegant

  if (Serial.available() > 0) //if something comes
  {
    receivedCommand = Serial.read(); // this will read the command character
    newData = true; //this creates a flag
  }

  if (newData == true) //if we received something (see above)
  {
    //START - MEASURE
    if (receivedCommand == 's') //this is the measure part
    {
      //example s 2000 500 - 2000 steps (5 revolution with 400 step/rev microstepping) and 500 steps/s speed
      runallowed = true; //allow running


      receivedMMdistance = Serial.parseFloat(); //value for the steps
      receivedDelay = Serial.parseFloat(); //value for the speed

      Serial.print(receivedMMdistance); //print the values for checking
      Serial.print(receivedDelay);
      Serial.println("Measure "); //print the action
      stepper.setMaxSpeed(receivedDelay); //set speed
      stepper.move(receivedMMdistance); //set distance

    }
    //START - OPEN
    if (receivedCommand == 'o') //OPENING
    {
      //example o 2000 500 - 2000 steps (5 revolution with 400 step/rev microstepping) and 500 steps/s speed
      runallowed = true; //allow running



      receivedMMdistance = Serial.parseFloat(); //value for the steps
      receivedDelay = Serial.parseFloat(); //value for the speed

      Serial.print(receivedMMdistance); //print the values for checking
      Serial.print(receivedDelay);
      Serial.println("OPEN "); //print the action
      stepper.setMaxSpeed(receivedDelay); //set speed
      stepper.move(receivedMMdistance); //set distance

    }

    //START - CLOSE
    if (receivedCommand == 'c') //CLOSING - Rotates the motor in the opposite direction as opening
    {
      //example c 2000 500 - 2000 steps (5 revolution with 400 step/rev microstepping) and 500 steps/s speed; will rotate in the other direction
      runallowed = true; //allow running



      receivedMMdistance = Serial.parseFloat(); //value for the steps
      receivedDelay = Serial.parseFloat(); //value for the speed

      Serial.print(receivedMMdistance);  //print the values for checking
      Serial.print(receivedDelay);
      Serial.println("CLOSE "); //print action
      stepper.setMaxSpeed(receivedDelay); //set speed
      stepper.move(-1 * receivedMMdistance); ////set distance - negative value flips the direction

    }

    //STOP - STOP
    if (receivedCommand == 'n') //immediately stops the motor
    {
      runallowed = false; //disable running

      stepper.setCurrentPosition(0); // reset position
      Serial.println("STOP "); //print action
      stepper.stop(); //stop motor
      stepper.disableOutputs(); //disable power

    }

    //SET ACCELERATION
    if (receivedCommand == 'a') //Setting up a new acceleration value
    {
      runallowed = false; //we still keep running disabled, since we just update a variable

      receivedAcceleration = Serial.parseFloat(); //receive the acceleration from serial

      stepper.setAcceleration(receivedAcceleration); //update the value of the variable

      Serial.println("ACC Updated "); //confirm update by message

    }

    //HOMING
    if (receivedCommand == 'h') //homing, this movement will be interrupted via the attachInterrupt() triggered by the microswitch.
    {
      runallowed = true; //allow running

      Serial.println("HOMING"); //print action
      stepper.setAcceleration(100); //defining some low acceleration
      stepper.setMaxSpeed(100); //set speed, 100 for test purposes
      stepper.move(-1 * 20000); ////set distance - negative value flips the direction
      //distance should be larger than the length of the whole path.
      //I don't think that this is a safe way of homing. if the switch fails, the motor will keep running anyway
    }

  }
  //after we went through the above tasks, newData becomes false again, so we are ready to receive new commands again.
  newData = false;


}

void stopMotor()//function activated by the pressed microswitch
{
  //Stop motor, disable outputs; here we should also reset the numbers if there are any
  runallowed = false; //disable running

      stepper.setCurrentPosition(0); // reset position
      Serial.println("STOP "); //print action
      stepper.stop(); //stop motor
      stepper.disableOutputs(); //disable power


  Serial.println("Pressed."); //feedback towards the serial port

  //This part might not work properly.
  digitalWrite(4,HIGH); //turn on LED
  delay(2000); //wait a bit
  digitalWrite(4,LOW); //turn off the LED

}