Arduino nano I2C as slaves and NodeMCU is master

#include "ESP8266WiFi.h"        //I can connect to a Wifi
#include "ESP8266WebServer.h"   //I can be a server 'cos I have the class ESP8266WebServer available
#include "WiFiClient.h"
#include <Wire.h>

const char *ssid = "ESP8266AP";  //Credentials to register network defined by the SSID (Service Set IDentifier)
const char *password = "123456654"; //and the second one a password if you wish to use it.
ESP8266WebServer server(80);    //Class ESP8266WebServer and default port for HTTP

int addr = 0; //This variable is related to the number of turns. If microstepping is disabled, 200 corresponds to a complete turn.
int wing = 0; //This variable is the pulse duration in milliseconds and it is related to the rotation speed. Without microstepping, 1.8º are stepDelay ms.

void handleRootPath() {
 server.send(200, "text/plain", "Ready, player one.");
}

void handleInit() {// Handler. 192.168.XXX.XXX/Init?Dir=HIGH&Delay=5&Steps=200 (One turn clockwise in one second)
addr = 0; //Motor stopped if the arguments are wrong.
wing = 0;
String message = "Initialization with: ";

 if (server.hasArg("Address")) {
 addr = (server.arg("Address")).toInt(); //Converts the string to integer.
 message += " Address: ";
 message += server.arg("Address");
 
 }
 if (server.hasArg("Wing")) {
 wing = (server.arg("Wing")).toInt();
 message += " Wing: ";
 message += server.arg("Wing");
 }
 server.send(200, "text/plain", message); //It's better to return something so the browser don't get frustrated+
 
 Wire.beginTransmission(addr); /* begin with device address 8 */
 Wire.write(wing);  /* sends integer */
 Wire.endTransmission();    /* stop transmitting */
 
}

void setup() {
Serial.begin(115200); //I can debbug through the serial port
// Configure NODEMCU as Access Point
Serial.println();
Wire.begin(D1, D2); /* join i2c bus with SDA=D1 and SCL=D2 of NodeMCU */
Serial.println("Configuring access point...");
WiFi.softAP(ssid, password); //Password is not necessary
IPAddress myIP = WiFi.softAPIP(); //Get the IP assigned to itself.
Serial.print("AP IP address: "); //This is written in the PC console.
Serial.println(myIP);

pinMode(2, OUTPUT); // Pins are outputs


server.on("/", handleRootPath);
server.on("/Init", handleInit);

server.begin(); //Let's call the begin method on the server object to start the server.
Serial.println("HTTP server started");
}

void loop() {
 server.handleClient();
}

#include <Wire.h>
unsigned int x;
bool f1 = 0 , f2 = 0, f3 = 0;

void setup() {
  Serial.begin(9600);
  pinMode(2, OUTPUT);
  pinMode(3, OUTPUT);
  pinMode(4, OUTPUT);
  digitalWrite(2, HIGH);
  digitalWrite(3, HIGH);
  digitalWrite(4 HIGH);
  Wire.begin(4);  // 1,2,3,4,5,6 Nanos                                                                                                                                                    // join i2c bus with address #8
  Wire.onReceive(receiveEvent); // register event
  delay(2000);
}

void loop() {
delay(50);
}

void receiveEvent(int howMany) {
 
  int x = Wire.read();    // receive byte as an integer
  Serial.println(x);         // print the integer
  if (x == 1) {
    f1=!f1;
    if (f1 == 0) {
    digitalWrite(2, HIGH);
    }
    if (f1 == 1) {
    digitalWrite(2, LOW);
    }
  }

  if (x == 2) {
    f2=!f2;
    if (f2 == 0) {
digitalWrite(3, HIGH);    }
    if (f2 == 1) {
digitalWrite(3, LOW);    }
  }

  if (x == 3) {
    f3=!f3;
    if (f3 == 0) {
digitalWrite(4, HIGH);    }
    if (f3 == 1) {
digitalWrite(4, LOW);    }
  }

}

#include "ESP8266WiFi.h"        //I can connect to a Wifi
#include "ESP8266WebServer.h"   //I can be a server 'cos I have the class ESP8266WebServer available
#include "WiFiClient.h"
#include <Wire.h>

const char *ssid = "ESP8266AP";  //Credentials to register network defined by the SSID (Service Set IDentifier)
const char *password = "*********"; //and the second one a password if you wish to use it.
ESP8266WebServer server(80);    //Class ESP8266WebServer and default port for HTTP

int addr = 0; //This variable is related to the number of turns. If microstepping is disabled, 200 corresponds to a complete turn.
int wing = 0; //This variable is the pulse duration in milliseconds and it is related to the rotation speed. Without microstepping, 1.8º are stepDelay ms.

void handleRootPath() {
  server.send(200, "text/plain", "Ready, player one.");
}

void handleInit() {// Handler. 192.168.XXX.XXX/Init?Dir=HIGH&Delay=5&Steps=200 (One turn clockwise in one second)
  addr = 0; //Motor stopped if the arguments are wrong.
  wing = 0;
  String message = "Initialization with: ";

  if (server.hasArg("Address")) {
    addr = (server.arg("Address")).toInt(); //Converts the string to integer.
    message += " Address: ";
    message += server.arg("Address");

  }
  if (server.hasArg("Wing")) {
    wing = (server.arg("Wing")).toInt();
    message += " Wing: ";
    message += server.arg("Wing");
  }
  server.send(200, "text/plain", message); //It's better to return something so the browser don't get frustrated+

  if (addr == 45 && (wing == 58 || wing == 59)) {
    for (int ad = 30 ; ad <= 40 ; ad = ad + 2) {
      Wire.beginTransmission(ad); /* begin with device address 8 */
      Wire.write(wing);  /* sends integer */
      Wire.endTransmission();    /* stop transmitting */
    }
  } else if ((addr==30 || addr==32 || addr==34 || addr==36 || addr==38 || addr==40) && (wing==50 || wing==52 || wing==54)) {
    Wire.beginTransmission(addr); /* begin with device address 8 */
    Wire.write(wing);  /* sends integer */
    Wire.endTransmission();    /* stop transmitting */
  }
}

void setup() {
  Serial.begin(115200); //I can debbug through the serial port
  // Configure NODEMCU as Access Point
  Serial.println();
  Wire.begin(D1, D2); /* join i2c bus with SDA=D1 and SCL=D2 of NodeMCU */
  Serial.println("Configuring access point...");
  WiFi.softAP(ssid, password); //Password is not necessary
  IPAddress myIP = WiFi.softAPIP(); //Get the IP assigned to itself.
  Serial.print("AP IP address: "); //This is written in the PC console.
  Serial.println(myIP);

  pinMode(2, OUTPUT); // Pins are outputs


  server.on("/", handleRootPath);
  server.on("/Init", handleInit);

  server.begin(); //Let's call the begin method on the server object to start the server.
  Serial.println("HTTP server started");
}

void loop() {
  server.handleClient();  //
}

#include <Servo.h>
#include <NewPing.h>
#include <Wire.h>
#define TRIGGER_PIN  2  // Arduino pin tied to trigger pin on the ultrasonic sensor.
#define ECHO_PIN     3  // Arduino pin tied to echo pin on the ultrasonic sensor.
#define MAX_DISTANCE 200 // Maximum distance we want to ping for (in centimeters). Maximum sensor distance is rated at 400-500cm.

Servo servo1, servo2, servo3;  // create servo object to control a servo
// twelve servo objects can be created on most boards
NewPing sonar(TRIGGER_PIN, ECHO_PIN, MAX_DISTANCE); // NewPing setup of pins and maximum distance.
volatile unsigned int x, f1 = 0 , f2 = 0, f3 = 0, f4 = 0;
unsigned long distanceDetect, distanceDetectMapped;
uint8_t tog = 0;
uint32_t oldtime = millis();
int pos = 45;    // variable to store the servo position
void setup() {
  servo1.attach(9);  // attaches the servo on pin 9 to the servo object
  servo1.write(45);
  servo2.attach(10);  // attaches the servo on pin 9 to the servo object
  servo2.write(45);
  servo3.attach(11);  // attaches the servo on pin 9 to the servo object
  servo3.write(45);
  Serial.begin(9600);
  Wire.begin(40);     // join i2c bus with address #30-40
  Wire.onReceive(receiveEvent); // register event
  delay(2000);
}

void loop() {

 // Serial.println(x);      // print the integer

  if (f4 == 1) {
    if ( (millis() - oldtime) > 400) {
      oldtime = millis();
      tog = !tog; // Invert
      if (tog) {
        distanceDetect = sonar.ping_cm();
        Serial.print("distanceDetect = ");
        Serial.println(distanceDetect);
        // distanceDetectMapped = map(distanceDetect, 0, 60, 45, 170);
        if (distanceDetect > 30 && distanceDetect < 40) {
          servo1.write(45);              // tell servo to go to position in variable 'pos'
          servo2.write(45);              // tell servo to go to position in variable 'pos'
          servo3.write(45);              // tell servo to go to position in variable 'pos'
        } else {
          servo1.write(170);              // tell servo to go to position in variable 'pos'
          servo2.write(170);              // tell servo to go to position in variable 'pos'
          servo3.write(170);              // tell servo to go to position in variable 'pos'
        }
      }
    }
  }
  if (f4 == 0) {
    if (f1 == 0) {
      servo1.write(45);              // tell servo to go to position in variable 'pos'
    }
    if (f1 == 1) {
      servo1.write(170);              // tell servo to go to position in variable 'pos'
    }

    if (f2 == 0) {
      servo2.write(45);              // tell servo to go to position in variable 'pos'
    }
    if (f2 == 1) {
      servo2.write(170);              // tell servo to go to position in variable 'pos'
    }

    if (f3 == 0) {
      servo3.write(45);              // tell servo to go to position in variable 'pos'
    }
    if (f3 == 1) {
      servo3.write(170);              // tell servo to go to position in variable 'pos'
    }
  }
}

void receiveEvent(int howMany) {
  //  while (1 < Wire.available()) { // loop through all but the last
  //    char c = Wire.read(); // receive byte as a character
  //    Serial.print(c);         // print the character
  //}
  x = Wire.read();        // receive byte as an integer

  if (x == 50) {
    f1 = !f1;
  }

  if (x == 52) {
    f2 = !f2;

  }

  if (x == 54) {
    f3 = !f3;

  }

  if (x == 58) {
    f4 = 1;
  }
  if (x == 59) {
    f4 = 0;
  }
}

package com.example.kineticwall;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

import com.android.volley.Request;
import com.android.volley.RequestQueue;
import com.android.volley.toolbox.StringRequest;
import com.android.volley.toolbox.Volley;

import org.json.JSONArray;
import org.json.JSONException;

import java.io.IOException;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;

public class MainActivity extends AppCompatActivity {
    TextView tv, textMode;
    EditText edt_steps, edt_direction, edt_delay;
    Button add1, add2, add3, add4, add5, add6, wing1, wing2, wing3, autoMan;
    String url = "", addr, wing, autoManButtonText;
    boolean flag = true;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        add1 = findViewById(R.id.add1);
        add2 = findViewById(R.id.add2);
        add3 = findViewById(R.id.add3);
        add4 = findViewById(R.id.add4);
        add5 = findViewById(R.id.add5);
        add6 = findViewById(R.id.add6);
        wing1 = findViewById(R.id.wing1);
        wing2 = findViewById(R.id.wing2);
        wing3 = findViewById(R.id.wing3);
        autoMan = findViewById(R.id.autoMan);
        autoMan.setText("Auto");
        tv = findViewById(R.id.tv);
        textMode = findViewById(R.id.textMode);
        textMode.setText("Manual Mode");
        if(flag) {
             manualMode();
        }
        autoMan.setOnClickListener(view -> {
            autoManButtonText = autoMan.getText().toString();
            if(autoManButtonText.equals("Auto")){
                //code for auto
                flag = false;
                autoMan.setText("Manual");
                textMode.setText("Auto Mode");
                addr = "45";
                wing = "58";
                url ="http://192.168.4.1/Init?"+ "Address=" + addr + "&" + "Wing=" + wing;
                System.out.println(url);
                requestVolley();
                url = "";
            }else{
                //code for manual
                flag = false;
                autoMan.setText("Auto");
                textMode.setText("Manual Mode");
                addr = "45";
                wing = "59";
                url ="http://192.168.4.1/Init?"+ "Address=" + addr + "&" + "Wing=" + wing;
                System.out.println(url);
                requestVolley();
                url = "";
                manualMode();

            }

        });


//
//        th = new Thread(() -> {
//            while(true){
//                try {
//                    Thread.sleep(500);
//                    requestVolley();
//
//                } catch (InterruptedException e) {
//                    e.printStackTrace();
//                }}
//        });th.start();
        // schedule();

    }

//    public void schedule() {
//        ScheduledExecutorService executor = Executors.newSingleThreadScheduledExecutor();
//        executor.scheduleAtFixedRate(this::requestVolley, 0, 500, TimeUnit.MILLISECONDS);
//    }
    public void manualMode(){

        add1.setOnClickListener(view -> {
            addr = "30";
        });
        add2.setOnClickListener(view -> {
            addr = "32";
        });
        add3.setOnClickListener(view -> {
            addr = "34";
        });
        add4.setOnClickListener(view -> {
            addr = "36";
        });
        add5.setOnClickListener(view -> {
            addr = "38";
        });
        add6.setOnClickListener(view -> {
            addr = "40";
        });


        wing1.setOnClickListener(view -> {
            wing = "50";
            url ="http://192.168.4.1/Init?"+ "Address=" + addr + "&" + "Wing=" + wing;
            System.out.println(url);
            requestVolley();
            url = "";
        });

        wing2.setOnClickListener(view -> {
            wing = "52";
            url ="http://192.168.4.1/Init?"+ "Address=" + addr + "&" + "Wing=" + wing;
            System.out.println(url);
            requestVolley();
            url = "";
        });

        wing3.setOnClickListener(view -> {
            wing = "54";
            url ="http://192.168.4.1/Init?"+ "Address=" + addr + "&" + "Wing=" + wing;
            System.out.println(url);
            requestVolley();
            url = "";
        });


    }

    private void requestVolley() {
        RequestQueue requestQueue = Volley.newRequestQueue(this);
        StringRequest stringRequest = new StringRequest(Request.Method.POST, url, response -> {
            try {
                tv.setText(String.valueOf(response));
                JSONArray jsonArray = new JSONArray(response);
                //   tv.setText(String.valueOf(jsonArray));
                //    JSONObject jsonObject = jsonArray.getJSONObject(0);
                //    String status = jsonObject.getString("message");
                //    if (status.equals("success")) {
                //       JSONObject data = jsonObject.getJSONObject("data");
                //       value = data.getString("value");
                //       tv.setText(value);
                //     }
            } catch (JSONException e) {
                e.printStackTrace();
            }

        }, error -> tv.setText(error.toString()));
//        stringRequest.setRetryPolicy(new DefaultRetryPolicy(
//                6000,
//                DefaultRetryPolicy.DEFAULT_MAX_RETRIES,
//                DefaultRetryPolicy.DEFAULT_BACKOFF_MULT)
//        );
        requestQueue.add(stringRequest);

    }
}