<> <> <> package com.example.bluetoothesp32; import android.Manifest; import android.bluetooth.BluetoothAdapter; import android.bluetooth.BluetoothDevice; import android.bluetooth.BluetoothSocket; import android.content.pm.PackageManager; import android.os.Build; import android.os.Bundle; import android.view.View; import android.widget.Button; import android.widget.Toast; import androidx.annotation.RequiresApi; import androidx.appcompat.app.AppCompatActivity; import androidx.core.app.ActivityCompat; import java.io.IOException; import java.io.OutputStream; import java.util.UUID; public class MainActivity extends AppCompatActivity { private BluetoothAdapter bluetoothAdapter; private BluetoothSocket bluetoothSocket; private OutputStream outputStream; // UUID estándar SPP private static final UUID MY_UUID = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB"); // CAMBIA esto por la MAC de tu ESP32 private static final String DEVICE_ADDRESS = "XX:XX:XX:XX:XX:XX"; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); bluetoothAdapter = BluetoothAdapter.getDefaultAdapter(); Button btnConectar = findViewById(R.id.btnConectar); Button btnA = findViewById(R.id.btnA); Button btnB = findViewById(R.id.btnB); Button btnC = findViewById(R.id.btnC); btnConectar.setOnClickListener(v -> conectarESP32()); btnA.setOnClickListener(v -> enviarDato("A")); btnB.setOnClickListener(v -> enviarDato("B")); btnC.setOnClickListener(v -> enviarDato("C")); } private void conectarESP32() { if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.S) { if (ActivityCompat.checkSelfPermission(this, Manifest.permission.BLUETOOTH_CONNECT) != PackageManager.PERMISSION_GRANTED) { ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.BLUETOOTH_CONNECT}, 1); return; } } try { BluetoothDevice device = bluetoothAdapter.getRemoteDevice(DEVICE_ADDRESS); bluetoothSocket = device.createRfcommSocketToServiceRecord(MY_UUID); bluetoothSocket.connect(); outputStream = bluetoothSocket.getOutputStream(); Toast.makeText(this, "Conectado al ESP32", Toast.LENGTH_SHORT).show(); } catch (IOException e) { e.printStackTrace(); Toast.makeText(this, "Error al conectar", Toast.LENGTH_SHORT).show(); } } private void enviarDato(String dato) { if (outputStream != null) { try { outputStream.write(dato.getBytes()); Toast.makeText(this, "Enviado: " + dato, Toast.LENGTH_SHORT).show(); } catch (IOException e) { e.printStackTrace(); } } } @Override protected void onDestroy() { super.onDestroy(); try { if (bluetoothSocket != null) { bluetoothSocket.close(); } } catch (IOException e) { e.printStackTrace(); } } } <> #include "BluetoothSerial.h" BluetoothSerial SerialBT; void setup() { SerialBT.begin("ESP32_BT"); } void loop() { if (SerialBT.available()) { char c = SerialBT.read(); Serial.println(c); } } <> package com.example.bluetoothesp32; import android.Manifest; import android.bluetooth.BluetoothAdapter; import android.bluetooth.BluetoothDevice; import android.bluetooth.BluetoothSocket; import android.content.pm.PackageManager; import android.os.Build; import android.os.Bundle; import android.os.Handler; import android.os.Looper; import android.widget.Button; import android.widget.Toast; import androidx.appcompat.app.AppCompatActivity; import androidx.core.app.ActivityCompat; import java.io.IOException; import java.io.OutputStream; import java.util.UUID; public class MainActivity extends AppCompatActivity { private BluetoothAdapter bluetoothAdapter; private ConnectThread connectThread; private ConnectedThread connectedThread; private static final UUID MY_UUID = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB"); private static final String DEVICE_ADDRESS = "XX:XX:XX:XX:XX:XX"; // MAC ESP32 private Handler handler = new Handler(Looper.getMainLooper()); @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); bluetoothAdapter = BluetoothAdapter.getDefaultAdapter(); Button btnConectar = findViewById(R.id.btnConectar); Button btnA = findViewById(R.id.btnA); Button btnB = findViewById(R.id.btnB); Button btnC = findViewById(R.id.btnC); btnConectar.setOnClickListener(v -> conectarESP32()); btnA.setOnClickListener(v -> enviar("A")); btnB.setOnClickListener(v -> enviar("B")); btnC.setOnClickListener(v -> enviar("C")); } private void conectarESP32() { if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.S) { if (ActivityCompat.checkSelfPermission(this, Manifest.permission.BLUETOOTH_CONNECT) != PackageManager.PERMISSION_GRANTED) { ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.BLUETOOTH_CONNECT}, 1); return; } } BluetoothDevice device = bluetoothAdapter.getRemoteDevice(DEVICE_ADDRESS); connectThread = new ConnectThread(device); connectThread.start(); } private void enviar(String mensaje) { if (connectedThread != null) { connectedThread.write(mensaje.getBytes()); } else { Toast.makeText(this, "No conectado", Toast.LENGTH_SHORT).show(); } } // ========================= // HILO DE CONEXIÓN // ========================= private class ConnectThread extends Thread { private final BluetoothDevice device; private BluetoothSocket socket; public ConnectThread(BluetoothDevice device) { this.device = device; try { socket = device.createRfcommSocketToServiceRecord(MY_UUID); } catch (IOException e) { e.printStackTrace(); } } public void run() { bluetoothAdapter.cancelDiscovery(); try { socket.connect(); handler.post(() -> Toast.makeText(MainActivity.this, "Conectado al ESP32", Toast.LENGTH_SHORT).show()); connectedThread = new ConnectedThread(socket); connectedThread.start(); } catch (IOException connectException) { handler.post(() -> Toast.makeText(MainActivity.this, "Error al conectar", Toast.LENGTH_SHORT).show()); try { socket.close(); } catch (IOException closeException) { closeException.printStackTrace(); } } } } // ========================= // HILO DE COMUNICACIÓN // ========================= private class ConnectedThread extends Thread { private final BluetoothSocket socket; private final OutputStream outputStream; public ConnectedThread(BluetoothSocket socket) { this.socket = socket; OutputStream tmp = null; try { tmp = socket.getOutputStream(); } catch (IOException e) { e.printStackTrace(); } outputStream = tmp; } public void write(byte[] bytes) { try { outputStream.write(bytes); handler.post(() -> Toast.makeText(MainActivity.this, "Enviado", Toast.LENGTH_SHORT).show()); } catch (IOException e) { e.printStackTrace(); } } public void cancel() { try { socket.close(); } catch (IOException e) { e.printStackTrace(); } } } @Override protected void onDestroy() { super.onDestroy(); if (connectedThread != null) { connectedThread.cancel(); } } }