// For: https://forum.arduino.cc/t/problem-with-nema-17-and-potentiometer/1031505
//
// Formatted the text a little.
// Changed pins to "const int", changed small other things.
// Added AccelStepper library.
// Added a 50Hz millis-timer to sample and average the sensor data.
// Added a low-pass filter.
// Show potentiometer value before and after filtering.
//

#include <AccelStepper.h>

const int stepPin = 6;
const int dirPin = 3;
const int potPin = A6;

AccelStepper stepper(AccelStepper::DRIVER, stepPin, dirPin);

const int sensorMin = 250;         // minimum sensor value
const int sensorMax = 800;         // maximum sensor value

float sensorValue;                 // a global variable for the filtered value

unsigned long previousMillis;
const unsigned long interval = 20; // for 50Hz sample rate

void setup()
{
  Serial.begin(115200);

  stepper.setMaxSpeed(500);
  stepper.setAcceleration(40);

  // Set the sensorValue to a initial value.
  // To make the filter start with a real value.
  sensorValue = getSensor(potPin);
}

void loop()
{
  unsigned long currentMillis = millis();

  // Sample the input with 50Hz.
  // That seems enough and a fixed timing is needed for the filter.
  if( currentMillis - previousMillis >= interval)
  {
    previousMillis = currentMillis;

    float newSensorValue = getSensor(potPin);
    Serial.print(newSensorValue);
    Serial.print(",");

    // Low-pass filter, for example with 5%.
    sensorValue = 0.95 * sensorValue + 0.05 * newSensorValue;
    Serial.print(sensorValue);
    Serial.println();

    // To do: Create a dead area.

    stepper.moveTo( (long) sensorValue);
  }

  stepper.run();        // this function makes the stepper motors move
}

// This function gets the sensor data.
// It returns 0...1000 as a floating point.
// Only a part of the potentiometer is used.
float getSensor(int pin)
{
  // Take 10 samples and calculate the average.
  // The result should be 0...1000.
  // Using floating point helps for the low-pas filter.
  long total = 0;
  for( int i=0; i<10; i++)
  {
    int pot = analogRead(pin);
    pot = constrain(pot, sensorMin, sensorMax);
    pot = map(pot, sensorMin, sensorMax, 0, 1000);
    total += pot;               // calculate the total of the samples
  }
  return(float(total) / 10.0);  // the average as a floating point
}