#include <Wire.h>
#include <ESP32Servo.h>

Servo myservo;

int pos = 0;

void setup() {
  myservo.attach(D0); 
  Wire.begin(0x8B);                // join i2c bus with address #8
  Wire.onReceive(receiveEvent); // register event
}

void loop() {
  delay(100);
}

void receiveEvent(int howMany){
   while (Wire.available()) {
    char c = Wire.read(); // Receive a byte
    decrypt(c); // Decrypt received byte and control servo
  }
}


void moveServo(int targetPosition) {
  int currentPos = myservo.read();
  if (currentPos < targetPosition) {
    for (pos = currentPos; pos <= targetPosition; pos++) {
      myservo.write(pos);
      delay(15);
    }
  } else {
    for (pos = currentPos; pos >= targetPosition; pos--) {
      myservo.write(pos);
      delay(15);
    }
  }
}

void decrypt(char var) {
  switch (var) {
    case 'A':
      moveServo(0);
      break;
    case 'B':
      moveServo(30);
      break;
    case 'C':
      moveServo(60);
      break;
    case 'D':
      moveServo(120);
      break;
    case 'E':
      moveServo(150);
      break;
    case 'F':
      moveServo(180);
      break;
    default:
      moveServo(90);
      break;
  }
}