We provide lighting with two or three LEDs that we connect to the microcontroller.
We made the Android program using the Flutter-Dart programming language.
 The chandelier part consists of paper cups, straws and glossy gelatin paper.
 

Below are the Flutter-Dart codes we wrote for the Android phone:

import 'dart:async';

//import 'dart:convert';

import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
 import 'package:flutter_bluetooth_serial/flutter_bluetooth_serial.dart';

void main()=> runApp(const MyApp());

class MyApp extends StatefulWidget {
   const MyApp({super.key});

  @override
  // ignore: library_private_types_in_public_api
  _MyAppState createState()=> _MyAppState();
 }

class _MyAppState extends State {
  List _devices=[];
  late BluetoothConnection connection;
   String adr="00:21:07:00:50:69"; // my bluetooth device MAC Adres

  @override
  void initState() {
    super.initState();
    _loadDevices();
   }

  Future _loadDevices() async {
     List devices=await FlutterBluetoothSerial.instance.getBondedDevices();

    setState(() {   _devices=devices;    });
  }
//----------------------------
   Future sendData(String data)  async {

    data=data.trim();
    try {
      List list=data.codeUnits;
      Uint8List bytes=Uint8List.fromList(list);
      connection.output.add(bytes);
      await connection.output.allSent;
      if (kDebugMode) {
        // print('Data sent successfully');
      }
    } catch (e) {
      //print(e.toString());
    }
   }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
        home: Scaffold(
          appBar: AppBar(
            title: const Text("Bluetooth Night LAMP Control"),
          ),
          body: Center(
            child: Column(
              mainAxisAlignment: MainAxisAlignment.center,
              children: [
                 const Text("MAC Adress: 00:21:07:00:50:69"),

                ElevatedButton(child:Text("Connect"),onPressed: () {
                  connect(adr);   },),
                SizedBox(height: 30.0,),
                ElevatedButton(child:Text(" YELLOW_ON "),onPressed: () {
                  sendData("yellow_on");  },),
                SizedBox(height: 10.0,),
                ElevatedButton(child:Text("YELLOW_OFF"),onPressed: () {
                  sendData("yellow_off"); },),
                 SizedBox(height: 10.0,),

                ElevatedButton(child:Text(" RED_ON "),onPressed: () {
                  sendData("red_on");  },),
                SizedBox(height: 10.0,),
                ElevatedButton(child:Text("RED_OFF"),onPressed: () {
                  sendData("red_off"); },),
                 SizedBox(height: 10.0,),

                ElevatedButton(child:Text(" BLUE_ON "),onPressed: () {
                  sendData("blue_on");  },),
                SizedBox(height: 10.0,),
                ElevatedButton(child:Text("BLUE_OFF"),onPressed: () {
                  sendData("blue_off"); },),
                 SizedBox(height: 10.0,),

              ],
            ),
           ),

        )

    );
   }

  Future connect(String address) async {
    try {
      connection=await BluetoothConnection.toAddress(address);
      sendData('111');
      //durum="Connected to the device";
      connection.input!.listen((Uint8List data) {
        //Data entry point
        // durum=ascii.decode(data);
       });

    } catch (exception) {
      // durum="Cannot connect, exception occured";
    }
   }

// --------------**************data gonder
//Future send(Uint8List data) async {
//connection.output.add(data);
//await connection.output.allSent;
}
 //------------*********** data gonder end

Below are the microcontroller codes:

#include 

SoftwareSerial mySerial(10, 11); // RX, TX

// YELLOW-->pin 7   RED--->pin 6     BLUE--->pin 5    ====> digital pins
String rec_data="off";

void setup() {
   pinMode(7, OUTPUT);
   pinMode(6, OUTPUT);
   pinMode(5, OUTPUT);
   
  Serial.begin(9600);
  mySerial.begin(9600);   // BlueTooth Data baud,set the data rate for the SoftwareSerial port
  
  digitalWrite(7,LOW);
  digitalWrite(6, LOW);
  digitalWrite(5, LOW);
}

void loop() { // run over and over
  if (mySerial.available()) {
    
    rec_data=mySerial.readString();
   
    if(rec_data=="yellow_on"){digitalWrite(7, HIGH);}
    if(rec_data=="yellow_off"){digitalWrite(7, LOW);}

    if(rec_data=="red_on"){digitalWrite(6, HIGH);}
    if(rec_data=="red_off"){digitalWrite(6, LOW);}

    if(rec_data=="blue_on"){digitalWrite(5, HIGH);}
    if(rec_data=="blue_off"){digitalWrite(5, LOW);}

    
    
    Serial.println(rec_data);
    delay(100);
  }
  
}