float voltage = 2.5;
float value = 0;
int i = 50;
int button = 2;
int steps = 0;
void setup() {
  pinMode(3, OUTPUT);
  pinMode(4, OUTPUT);
  Serial.begin(9600);

}

void loop() {
  value = (voltage * 255) / 13;
  stepperVoltageControl(value, 9, 6, 5, 3);

}
void stepperVoltageControl(float value, int motorPin1, int motorPin2,
                           int motorPin3, int motorPin4) {
  if (Serial.available() > 0) {
    steps = Serial.parseInt();
    i = 0;
  }
  if (digitalRead(button) == HIGH) {
    steps = 50;
    i = 0;
  }
  for (i ; i < steps; i++) {
    analogWrite(motorPin1, value);
    analogWrite(motorPin2, 0);
    analogWrite(motorPin3, value);
    analogWrite(motorPin4, 0);
    delay(20);
    analogWrite(motorPin1, 0);
    analogWrite(motorPin2, value);
    analogWrite(motorPin3, value);
    analogWrite(motorPin4, 0);
    delay(20);
    analogWrite(motorPin1, 0);
    analogWrite(motorPin2, value);
    analogWrite(motorPin3, 0);
    analogWrite(motorPin4, value);
    delay(20);
    analogWrite(motorPin1, value);
    analogWrite(motorPin2, 0);
    analogWrite(motorPin3, 0);
    analogWrite(motorPin4, value);
    delay(20);
  }
}