#include <ESP32Servo.h>

Servo myservo;
int pos = 0; // variable to store the servo position

void setup() {
  myservo.attach(20);  // attach the servo on pin 9 to the servo object
  Serial.begin(9600);  // start serial communication at 9600bps
}

void loop() {
  if (Serial.available() > 0) {
    int command = Serial.read();  // read the incoming byte
    if (command == '1') {
      // Rotate servo
      for (pos = 0; pos <= 180; pos += 1) { 
        myservo.write(pos);             
        delay(15);                       
      }
    } else if (command == '0') {
      // Stop servo (return to position 0)
      myservo.write(0);
    }
  }
}