#include <Servo.h> //Importação da biblioteca

Servo myservo; //Instância da classe Servo

#define btn1 13
#define btn2 12
#define btn3 11

void setup() {
  myservo.attach(9); //Algum pino PWM (~)

  pinMode(btn1, INPUT_PULLUP);
  pinMode(btn2, INPUT_PULLUP);
  pinMode(btn3, INPUT_PULLUP);

  Serial.begin(9600);
}

void loop() {

  Serial.println(digitalRead(btn1));
  Serial.println(digitalRead(btn2));
  Serial.println(digitalRead(btn3));
  Serial.println("===========");


  if(!digitalRead(btn1)){
    myservo.write(0); 
  } else if(!digitalRead(btn2)){
    myservo.write(90); 
  } else if(!digitalRead(btn3)){
    myservo.write(180); 
  }

  delay(100);
}