#include <Servo.h>
// creación de objetos servo
Servo servoMetal;
Servo servoNoMetal;
// terminales de conexión Arduino a servos
int ServoMetal = 10;
int ServoNoMetal = 11;
// variables para manejar los servos
int pos01 = 90;
int pos02 = 90;
// Stepper Motor Coil
int Coil01 = 6;
int Coil02 = 7;
int Coil03 = 8;
int Coil04 = 9;
// delay para cebado de bobinas de stepper
int espera = 20;

char data;
void setup() {
  Serial.begin(38400);
  pinMode(Coil01,OUTPUT);
  pinMode(Coil02,OUTPUT);
  pinMode(Coil03,OUTPUT);
  pinMode(Coil04,OUTPUT);
  servoMetal.attach(ServoMetal);
  servoNoMetal.attach(ServoNoMetal); 
  servoMetal.write(pos01);
  servoNoMetal.write(pos02);
}

void loop() {
  if (Serial.available()>0){
    data = Serial.read();
    if (data == 'a'){
      digitalWrite(Coil01,LOW);
      digitalWrite(Coil02,HIGH);
      digitalWrite(Coil03,HIGH);
      digitalWrite(Coil04,LOW);
      delay(espera);
      digitalWrite(Coil01,LOW);
      digitalWrite(Coil02,LOW);
      digitalWrite(Coil03,HIGH);
      digitalWrite(Coil04,HIGH);
      delay(espera);
      digitalWrite(Coil01,HIGH);
      digitalWrite(Coil02,LOW);
      digitalWrite(Coil03,LOW);
      digitalWrite(Coil04,HIGH);
      delay(espera);
      digitalWrite(Coil01,HIGH);
      digitalWrite(Coil02,HIGH);
      digitalWrite(Coil03,LOW);
      digitalWrite(Coil04,LOW);
      delay(espera);
      data == '0';
    }
    if (data == 'b'){
      digitalWrite(Coil01,HIGH);
      digitalWrite(Coil02,HIGH);
      digitalWrite(Coil03,LOW);
      digitalWrite(Coil04,LOW);
      delay(espera);    
      digitalWrite(Coil01,HIGH);
      digitalWrite(Coil02,LOW);
      digitalWrite(Coil03,LOW);
      digitalWrite(Coil04,HIGH);
      delay(espera);
      digitalWrite(Coil01,LOW);
      digitalWrite(Coil02,LOW);
      digitalWrite(Coil03,HIGH);
      digitalWrite(Coil04,HIGH);
      delay(espera);
      digitalWrite(Coil01,LOW);
      digitalWrite(Coil02,HIGH);
      digitalWrite(Coil03,HIGH);
      digitalWrite(Coil04,LOW);
      delay(espera);
      data == '0';
    } 
    if (data == 'c'){
      for (pos01 = 90; pos01 >= 0; pos01 -= 1) {
        servoMetal.write(pos01);
        delay(15);
      }
      for (pos01 = 0; pos01 <= 90; pos01 += 1) {
        servoMetal.write(pos01);
        delay(15);
      }
      data == '0';
    } 
    if (data == 'd'){
      for (pos02 = 80; pos02 >= 0; pos02 -= 1) {
        servoNoMetal.write(pos02);
        delay(15);
      }   
      for (pos02 = 0; pos02 <= 80; pos02 += 1) {
        servoNoMetal.write(pos02);
        delay(15);
      }
      data == '0';
    }
    data == '0'
  }   
}