#define dirPin 2
#define stepPin 3
#define endPin 4

int stepSpeedUp = 1500;     // Motor speed - UP - min 500
int stepSpeedDown = 1500;   // Motor speed - DOWN - min 500
long maxStep = 54000;       // Max steps

int stepSpeed = 0;
bool dir = true;
long stepCount = 0;
bool rodEnd = false;

void setup() {
  Serial.begin(9600);
  pinMode(stepPin, OUTPUT);
  pinMode(dirPin, OUTPUT);
  pinMode(endPin, INPUT);
  digitalWrite(dirPin, dir);

  while(!rodEnd) {
    Serial.print(stepSpeed);
    Serial.print(" - ");
    Serial.print(stepCount);
    Serial.println("↓");

    stepCount++;
    stepSpeed = stepCount < 500 ? ((stepSpeedDown / 500) * stepCount) : stepSpeedDown;

    digitalWrite(stepPin, HIGH);
    delayMicroseconds(stepSpeed);
    digitalWrite(stepPin, LOW);
    delayMicroseconds(stepSpeed);

    if(digitalRead(endPin)) {
      rodEnd = true;
      stepCount = 0;
    }
  }

  Serial.println("START");

}

void loop() {

  Serial.print(stepSpeed);
  Serial.print(" - ");
  Serial.print(stepCount);
  Serial.print(" ");

  if(!dir) {
    stepCount++;
  
    if(stepCount >= maxStep) {
      dir = !dir;
      digitalWrite(dirPin, dir);
      delay(3000);
    } else {
      
      if(stepCount < (maxStep - 500)) {
        stepSpeed = stepCount < 500 ? ((stepSpeedUp / 500) * stepCount) : stepSpeedUp;
      } else {
        stepSpeed = (stepSpeedUp / 500) * (maxStep - stepCount);
      }
      
      digitalWrite(stepPin, HIGH);
      delayMicroseconds(stepSpeed);
      digitalWrite(stepPin, LOW);
      delayMicroseconds(stepSpeed);
      Serial.println("↑");
    }
    
  } else {

    stepCount--;
    
    if(stepCount <= 0) {
      dir = !dir;
      digitalWrite(dirPin, dir);
      delay(3000);
    } else {
    
      if(stepCount > 500) {
        stepSpeed = stepCount > (maxStep - 500) ? ((stepSpeedDown / 500) * (maxStep - stepCount)) : stepSpeedDown;
      } else {
        stepSpeed = (stepSpeedDown / 500) * stepCount;
      }
  
      digitalWrite(stepPin, HIGH);
      delayMicroseconds(stepSpeed);
      digitalWrite(stepPin, LOW);
      delayMicroseconds(stepSpeed);
      Serial.println("↓");
    }

  }

}


void serialEvent() {
  while (Serial.available()) {
    char inChar = (char)Serial.read();
    switch(inChar) {
      case 's':
        maxStep = stepCount;
        Serial.print("###################################");
        Serial.println(stepCount);
    }
  }
}