#define potentiometer  34  // Analog pin for the potentiometer
#define bt_F 35 // Clockwise Button
#define bt_S 12 // Stop Button
#define bt_B 13 // Anticlockwise Butto

#define dirPin  16  // GPIO pin for Direction of stepper motor driver 
#define stepPin 17  // GPIO pin for Step of stepper motor driver 
#define enPin   21 // GPIO pin for Enabled of stepper motor driver  

int read_ADC;
int Speed_Delay;
int Mode=1, flag=0;

void setup() { 
  pinMode(potentiometer, INPUT); // declare potentiometer as input 

  pinMode(bt_F, INPUT_PULLUP); // declare bt_F as input
  pinMode(bt_S, INPUT_PULLUP); // declare bt_S as input
  pinMode(bt_B, INPUT_PULLUP); // declare bt_B as input

  pinMode(dirPin,  OUTPUT); // declare as output for Direction of stepper motor driver 
  pinMode(stepPin, OUTPUT); // declare as output for Step of stepper motor driver 
  pinMode(enPin,   OUTPUT); // declare as output for Enabled of stepper motor driver  
}

void loop() { 
  read_ADC = analogRead(potentiometer); // read analogue to digital value 0 to 4095 (12-bit ADC)
  Speed_Delay = map(read_ADC, 0, 4095, 5000, 10); // value map for Microstep resolution Delay

  if(digitalRead (bt_F) == 0) { // For Clockwise
    Mode = 2; 
    digitalWrite(enPin, LOW);
  }
  
  if(digitalRead (bt_S) == 0) { // For Stop
    if(flag == 0) {
      flag = 1;
      if(Mode > 1) Mode = 1; 
      else {
        Mode = !Mode; 
        if(Mode == 0) digitalWrite(enPin, HIGH);
        else digitalWrite(enPin, LOW);
      }
      delay(100);
    }
  } else { 
    flag = 0; 
  } 

  if(digitalRead (bt_B) == 0) { // For Anticlockwise
    Mode = 3; 
    digitalWrite(enPin, LOW);
  }

  if(Speed_Delay > 0 && Mode > 1) { 
    if(Mode == 2) digitalWrite(dirPin, LOW); // Stepper motor rotates CW (Clockwise)
    else digitalWrite(dirPin, HIGH); // Stepper motor rotates CCW (Anticlockwise)

    digitalWrite(stepPin, HIGH);
    delayMicroseconds(Speed_Delay);
    digitalWrite(stepPin, LOW);
    delayMicroseconds(Speed_Delay);
  }  
}