WiFi P2P network in Android Things

See also questions close to this topic

• How to send data from Android to Arduino in Xamarin.Android using SPP with HC - 06

  I am currently able to read data sent to the Android phone from the Arduino, but I get nothing on the Arduino end when I try to send data.

  Below is my BluetoothManager class that gets instantiated and set up in the main activity. The .sendDataToDevice(String data) method is then called with the data you want to send. I've searched the internet quite a bit, but I am having trouble finding examples that are close to how this code is set up. I'm thinking that I am probably doing something wrong with the output stream, but am not sure. Any help would be appreciated!

  using System;
  using System.Collections.Generic;
  using System.Linq;
  using System.Text;
  
  using Android.App;
  using Android.Bluetooth;
  using Android.Content;
  using Android.OS;
  using Android.Runtime;
  using Android.Views;
  using Android.Widget;
  using Java.IO;
  using Java.Util;
  
  namespace BluetoothTest
  {
      class BluetoothManager
      {
          //Unique ID which helps us connect to any device 
          private const string UuidUniverseProfile = "00001101-0000-1000-8000-00805f9b34fb";
          //Represent bluetooth data coming from UART
          private BluetoothDevice result;
          //get input/output stream of this comunication
          private BluetoothSocket mSocket;
          //convert byte[] to readable strings
          private BufferedReader reader;
          private BufferedWriter writer;//----------------------
          private System.IO.Stream mStream;
          private InputStreamReader mReader;
  
          private System.IO.Stream oStream;
          private OutputStreamWriter oWriter;//-------------------
  
  
  
          public BluetoothManager()
          {
              reader = null;
              writer = null;//---------------------------
          }
  
  
  
          public UUID getUUIDFromString()
          {
              return UUID.FromString(UuidUniverseProfile);
          }
  
  
  
          private void close(IDisposable aConnectableObject)
          {
              if (aConnectableObject == null) return;
              try
              {
                  aConnectableObject.Dispose();
              }
              catch(Exception)
              {
                  throw;
              }
              aConnectableObject = null;
          }
  
  
          public String getDataFromDevice()
          {
              return reader.ReadLine();
          }
  
          public void sendDataToDevice(String data)//---------------
          {
              writer.Write(data.ToCharArray());//------------------------         
          }
  
  
          private void openDeviceConnection(BluetoothDevice btDevice)
          {
              try
              {
                  //Getting socket from specific device
                  mSocket = btDevice.CreateRfcommSocketToServiceRecord(getUUIDFromString());
                  //blocking operation
                  mSocket.Connect();
                  //input stream
                  mStream = mSocket.InputStream;
                  //output stream
                  //mSocket.OutputStream;
                  oStream = mSocket.OutputStream;//----------------------------------
  
                  oWriter = new OutputStreamWriter(oStream);//--------------------------
                  writer = new BufferedWriter(oWriter);//-------------------------------
  
                  mReader = new InputStreamReader(mStream);
                  reader = new BufferedReader(mReader);
              }
              catch(IOException e)
              {
                  //Close all
                  close(mSocket);
                  close(mStream);
                  close(mReader);
                  close(oStream);
                  close(oWriter);//----------------------------------
                  throw e;
              }
          }
  
  
          public void getAllPairedDevices()
          {
               //your android phone bluetooth device
              BluetoothAdapter btAdapter = BluetoothAdapter.DefaultAdapter;
  
              var devices = btAdapter.BondedDevices;
              if(devices != null && devices.Count > 0)
              {
                  foreach (BluetoothDevice mDevice in devices)
                  {
                      //search threw all paired devices
                      //mDevice.Name.Split(' ');
                      openDeviceConnection(mDevice);
                  }
              }
          }
      }
  }
  
• How to Handle Pairing of Bluetooth BLE device when application is killed?

  I am working on application in which i have to connect to BLE devices and send them notification from application. I have succeeded in connecting and sending notification when application is in forground, When my application is killed the devices is connected but notification is not send to BLE device for updating status. I have created Background services and Job Scheduler to handle the communication between BLE and my application.

  For Connecting BLE Device I have used this method.
  

  BluetoothDevice mDevice; BluetoothGatt mConnGatt;

  mConnGatt = mDevice.connectGatt(mContext, true, new BluetoothGattCallback() {});

  When Push notification received then Write data on BLE device by using this method: /* * * * WRITE DATA ON BLE DEVICE *BluetoothGattCharacteristic mWriteGattCharacteristic; * */

  private void writeDataOnGatt(final int value) {
      Log.e("GATT_BLINKING_CLASS", "writeDataOnGatt");
      if (mWriteGattCharacteristic != null) {
          // This method is only called for LED characteristic
          mWriteGattCharacteristic.setValue(value, BluetoothGattCharacteristic.FORMAT_UINT8, 0);
          final int data = mWriteGattCharacteristic.getIntValue(BluetoothGattCharacteristic.FORMAT_UINT8, 0);
          Log.e("GATT_BLINKING_CLASS", "     DATA       " + data);
          if (mBluetoothGatt != null) {
              Log.e("GATT_BLINKING_CLASS", "writeDataOnGatt INSIDE");
              mBluetoothGatt.writeCharacteristic(mWriteGattCharacteristic);
          }
      } 
  }
  
• Can bluetooth cause hands to shake?

  Can bluetooth technology cause hands to shake?

  For a dozen or more years, since bluetooth technology caught on, I've experienced this. Any time I'm within ~a foot of a Bluetooth-equipped/active mouse, cell phone earpiece, or speaker, my hands start shaking a little, like early-stage Parkinson's.

  I turn off the bluetooth device, and my hands stop shaking. I turn it back on and it starts again.

  I can't find any mention anywhere online of this happening to anyone else. Have any of you experienced this or heard of anyone who has?
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  I am not able to install the WiFi drivers on newly installed OpenSuse Leap 15.0. [My wifi chipset is - 0bda:b009 realtek semiconductor corp] See below image:

  I have tried looking up for the hardware information using this

  hwinfo --wlan --short
  

  But there is no hardware listed for "wlan".

  I checked the hardware information through yast and found that the wifi driver is enlist as bluetooth. Please see below:

  What should I do to get Wifi working? I am not sure what might have caused this.

  Thanks in advance for any help regarding this.
• How to check WCN chip vendor of my Android Smartphone

  I want to know the vendor of the WCN (Wifi,BT,GPS) chip of my phone.

  1. Have searched in about phone information there is no such information regarding WCN chip vendor.
  2. Checked on different websites like GSM arena etc. Only the Chipset company name is there (like, Qualcomm snapdragon, Mediatek and Spreadtrum). No information regarding Wifi chip maker, like Brodcom etc.
  3. Have checked in sniffer logs of wifi. There is a field named Vendor specific in the Becon frame. Don't know exact what information does it display. Can anyone please explain this too ? there is very less data available on internet about this.

  Any help will be appreciated.

  Thanks
• Connect WIFI linux (WPA2- Enterprise)

  I have a problem when I want to connect the wifi. My wpa_supplicant is:

  # allow frontend (e.g., wpa_cli) to be used by all users in 'wheel' group
  ctrl_interface=/var/run/wpa_supplicant
  ctrl_interface_group=wheel
  
  # home network; allow all valid ciphers
  network={
    priority=1
    mode=0
    ssid="WiFi1"
    proto=RSN
    key_mgmt=WPA-EAP
    eap=PEAP
    identity="domain\user"
    password="my_pass"
    scan_ssid=1
    phase2="auth=MSCHAPV2"  
  }
  

  And my etc/network/interfaces:

  auto lo
  iface lo inet static
      address 127.0.0.1
      netmask 255.0.0.0
  
  # Wireless interfaces
  auto wlan0
  iface wlan0 inet dhcp
      pre-up wpa_supplicant -i wlan0 -c /etc/wpa_supplicant.conf -B
  
  auto eth0
  iface eth0 inet dhcp
  

  I have this configuration but when I connect the wlan0: sudo ifup wlan0 the wpa_state is always SCANNING What is happened? Am I doing somwthing wrong?
• Reducing jitter in Android's WiFi direct communication using UDP transport protocol

  I'm working on a real-time application that requires transmitting about 512 bytes of data every 5ms over a WiFi direct connection from a slave phone/s to a master (group owner). Average transmission delay is about 15ms, which is not that good, but the biggest issue is that I noticed a quite consistent pattern of periods where delay is as much as 100ms about every 2~3 seconds, plus periods of about 9 seconds every minute where throughput greatly reduces. Please take a look at the graph scatter graph of delay over time. I also attached my socket programming code. Both master and slave internal clocks are synchronized within a 1ms error (don't worry about clock drift). Please let me know if you too have experienced these results and whether there is something that can be done to improve on this issue. Interestingly enough there is typically 0 data loss, and when a packet gets delayed all packets before it too (easy to see from the graph) even though this is UDP. I read somewhere that packets need to get acknowledged at the MAC layer even if UDP is used, and this is what might be causing delays of about 100ms.

  The following is the code at the slave (sender):

  public class DataTransmissionServiceV3 {
  
  public static final String TAG = "DataTransmissionService";
  
  private long mClockOffset;
  private DatagramChannel mDatagramChannel;
  private boolean running;
  
  public void start(InetAddress remoteAddress, long clockOffset) {
      if (!running) {
          running = true;
          mClockOffset = clockOffset;
          Thread t = new Thread(new TransmissionTask(remoteAddress));
          t.setPriority(Thread.MAX_PRIORITY);
          t.start();
      }
  }
  
  public void close() {
      running = false;
      if (mDatagramChannel != null) {
          mDatagramChannel.socket().close();
      }
  }
  
  private class TransmissionTask implements Runnable {
  
      private int mCount;
      private final ByteBuffer mByteBuffer = ByteBuffer.allocateDirect(
              Constants.DATA_PACKET_SIZE);
      private final byte[] mBytes = new byte[Constants.DATA_PACKET_SIZE];
      private final InetAddress mRemoteAddress;
  
      public TransmissionTask(final InetAddress remoteAddress) {
          mRemoteAddress = remoteAddress;
      }
  
      @Override
      public void run() {
          try {
              mDatagramChannel = DatagramChannel.open();
              mDatagramChannel.socket().connect(new InetSocketAddress(mRemoteAddress,
                      Constants.TRANS_MASTER_SERVER_PORT));
              mDatagramChannel.configureBlocking(false);
          } catch (IOException ioe) {
              Log.e(TAG, "Exception while connecting", ioe);
          }
          while (running) {
              TimeUtils.busyWait(5000000); // busy wait for 5ms
              send();
          }
      }
  
      private void send() {
          mCount++;
          DataPacket.setSequenceNumber(mBytes, mCount);
          DataPacket.setTimestamp(mBytes, TimeUtils.getTimestamp() + mClockOffset); // synchronized timestamp to master device to measure delay
          mByteBuffer.clear();
          mByteBuffer.put(mBytes);
          mByteBuffer.flip();
          try {
              mDatagramChannel.write(mByteBuffer);
          } catch (Exception e) {
              Log.e(TAG, "Exception while sending data packet", e);
              running = false;
          }
      }
  }
  

  }

  And the following is the code at the master (receiver):

  public class DataTransmissionServerV3 {
  
  public static final String TAG = "DataTransmissionServer";
  
  private DatagramChannel mDatagramChannel;
  private boolean mRunning;
  private Handler mHandler;
  
  public DataTransmissionServerV3(Handler handler) {
      mHandler = handler;
  }
  
  public void start(InetAddress localAddress) {
      if (!mRunning) {
          mRunning = true;
          Thread t = new Thread(new ReceiveDataTask(localAddress));
          t.setPriority(Thread.MAX_PRIORITY);
          t.start();
      }
  }
  
  public void close() {
      mRunning = false;
      if (mDatagramChannel != null) {
          mDatagramChannel.socket().close();
      }
  }
  
  private class ReceiveDataTask implements Runnable {
  
      private final InetAddress mLocalAddress;
      private final ByteBuffer mByteBuffer = ByteBuffer.allocateDirect(
              Constants.DATA_PACKET_SIZE);
      private final byte[] mBytes = new byte[Constants.DATA_PACKET_SIZE];
      private int mCount;
  
      public ReceiveDataTask(final InetAddress localAddress) {
          mLocalAddress = localAddress;
      }
  
      @Override
      public void run() {
          try {
              bind();
              while (mRunning) {
                  receive();
              }
          } catch (IOException ioe) {
              Log.e(TAG, "Exception while binding datagram socket", ioe);
          }
      }
  
      private void bind() throws IOException {
          mDatagramChannel = DatagramChannel.open();
          mDatagramChannel.socket().bind(new InetSocketAddress(mLocalAddress,
                  Constants.TRANS_MASTER_SERVER_PORT));
          mDatagramChannel.configureBlocking(true);
      }
  
      private boolean receive() {
          mByteBuffer.clear();
          try {
              SocketAddress isa = mDatagramChannel.receive(mByteBuffer);
              long t2 = TimeUtils.getTimestamp();
              if (isa != null) {
                  mByteBuffer.flip();
                  mByteBuffer.get(mBytes);
                  mCount++;
                  TransmissionStat stat = TransmissionStat.get(mBytes, mCount, t2);
                  handlePacket(stat); // a statistic that is saved to file for later analysis (ignore this)
                  return true;
              }
          } catch (IOException ioe) {
              Log.e(TAG, "Exception while receiving data", ioe);
              mRunning = false;
          }
          return false;
      }
  
      private void handlePacket(TransmissionStat stat) {
          Message msg = mHandler.obtainMessage();
          msg.what = Constants.TRANSMISSION_PACKET_RECEIVED_CODE;
          msg.obj = stat;
          msg.sendToTarget();
      }
  }
  
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  I have 2 android devices both are connected to each other via Wi-Fi direct.

  Device A (Android device): No internet connection.

  Device B (Android Smartphone): Mobile data available.

  Is it possible to surf internet on device B while devices are connected and files are being transferred via Wi-Fi direct.
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  Using Wifi direct on Android I'm trying to share my internet connection to my connected clients.

  I've seen that there is a way to achieve it by creating a VPN routing. I do not find any examples on how to do it.

  Any help or guidance is appreciated.
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  I bought Android Starter Kit Pico NXP i.MX7D. I'm developping an application that requires root access, in particular I have to use a particular module of xPosed framework, but it requires root permission. I have just tried to obtain the access using many root-app for Android (such as Framaroot, KingoRoot, Rootmaster, z4root, ecc.) but nothing work.

  Someone knows if exist a method to accomplish my purpose?
• Get SSL Certificate from HttpURLConnection

  I'm working with an Android Things Raspberry Pi.
  I need to get the date and time updated as quick as possible, but the OS takes approximatively 50 seconds, that's too slow for my need.
  I used ipgeolocation services and lib to get current time.
  The problem is that before the date is set by the OS, the http request to get date and time fail : The HttpURLConnection used doesn't load the correct SSL certificate. After the date is updated by the OS, my attempt to get date work : I can get the date manually, after it's been set by the OS...

  So I would like to know wich certificate is used by the OS, extract it and manually use it with my HttpURLConnection to ask for date and time BEFORE the OS.

  I found how to make a request with a certain certificate, my trouble is that I don't find the one used automatically by the OS.

  Is there a way to know which certificate is automatically used by the OS for HttpURLConnection ?

  Thanks for reading
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  I'm running a build from the Android Things Console built with several custom apks

  One of the apps is failing with "{AppName}" has stopped. Open app again" The cause appears isolated to only one Configuration.

  I'm trying to get to root cause, normally I would run "adb logcat" to view full details with android. Is adb logcat support with Android Things build? Is a mechanism such as logcat available in Android Things when built with a build from the Android Things Console? If not, is there an alternative?
• RecyclerView not being updated with [WIFI DIRECT] discovery

  I have a database(SQLite) with specific "device names" and will be added to a RecyclerView while changing the TextView to Online/Offline depending on the device status.

  Devices status are determined when I do an onClickListener of a button running this:

  refreshBtn.setOnClickListener(new View.OnClickListener() {
      @Override
      public void onClick(View view) {
          mManager.discoverPeers(mChannel, new WifiP2pManager.ActionListener() {
              @Override
              public void onSuccess() {
                  Toast.makeText(getApplicationContext(),"Scanning for devices",Toast.LENGTH_LONG).show();
              }
  
              @Override
              public void onFailure(int reason) {
                  Toast.makeText(getApplicationContext(),"Scanning failed",Toast.LENGTH_LONG).show();
              }
          });
      }
  });
  

  PeerListListener:

    WifiP2pManager.PeerListListener peerListListener = new WifiP2pManager.PeerListListener() {
          @Override
          public void onPeersAvailable(WifiP2pDeviceList peerList) {
              loadingBar.setVisibility(View.VISIBLE);
              if(!peerList.getDeviceList().equals(peers)){
                  peers.clear();
                  peers.addAll(peerList.getDeviceList());
  
                  deviceNameArray = new String[peerList.getDeviceList().size()];
                  deviceArray     = new WifiP2pDevice[peerList.getDeviceList().size()];
                  int index       = 0;
                  int dbindex;
  
                  //loadingBar.setMax(deviceDetails.size());
                  //loadingBar.setProgress(0);
  
                  for(WifiP2pDevice device : peerList.getDeviceList()){
                      deviceNameArray[index] = device.deviceName;
  
  
                      System.out.printf(deviceNameArray[index]);
  
  
                      deviceArray[index]     = device;
                      for(dbindex = 0;dbindex<deviceDetails.size();dbindex++) {
                          if(!deviceDetails.get(dbindex).getStatus().equals("lock") || !deviceDetails.get(dbindex).getStatus().equals("maintenance")) {
                              if (deviceDetails.get(dbindex).getDeviceNo().equals(deviceNameArray[index])) {
                                  deviceDetails.get(dbindex).setStatus("online");
                              } else {
                                  deviceDetails.get(dbindex).setStatus("offline");
                              }
                          }
                      }
                      index++;
                      //loadingBar.setProgress(index);
                  }
                  mAdapter = new DeviceAdapter(UserMain.this,deviceDetails);
                  mAdapter.notifyDataSetChanged();
                  mRecyclerView.setAdapter(mAdapter);
  
  //                ArrayAdapter<String> adapter = new ArrayAdapter<String>(getApplicationContext(),android.R.layout.simple_list_item_1,deviceNameArray);
  //                listView.setAdapter(adapter);
              }
              if(peers.size() == 0){
                  Toast.makeText(getApplicationContext(),"No Device Found..",Toast.LENGTH_SHORT).show();
                  return;
              }
              loadingBar.setVisibility(View.INVISIBLE);
          }
      };
  

  I tried printing the deviceNameArray and the devices do show up on the console name but the RecycleView isn't updated at all.

  Part of my RecyclerView Custom Adapter:

  @NonNull
  @Override
  public DeviceAdapter.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
      View v = LayoutInflater.from(parent.getContext())
              .inflate(R.layout.user_main_card,parent,false);
  
      ViewHolder vh = new ViewHolder(v);
      return vh;
  }
  
  @Override
  public void onBindViewHolder(@NonNull DeviceAdapter.ViewHolder holder, final int position) {
      holder.deviceNo.setText("No." +deviceDetails.get(position).getDeviceNo());
  
      if(deviceDetails.get(position).getStatus().equals("online")) {
          holder.deviceStatus.setText("ONLINE");
      }else if(deviceDetails.get(position).getStatus().equals("offline") || deviceDetails.get(position).getStatus().equals("maintenance")){
          if(deviceDetails.get(position).getStatus().equals("offline")){
              holder.deviceStatus.setText("OFFLINE");
  
          }else if(deviceDetails.get(position).getStatus().equals("maintenance")){
              holder.deviceStatus.setText("MAINTENANCE");
  
          }
      }
  
  
  
      holder.cardView.setOnClickListener(new View.OnClickListener() {
          @Override
          public void onClick(View view) {
              if(deviceDetails.get(position).getStatus().equals("offline") || deviceDetails.get(position).getStatus().equals("maintenance")) {
                  Toast.makeText(mContext, deviceDetails.get(position).getDeviceName(), Toast.LENGTH_SHORT).show();
              }
              if(deviceDetails.get(position).getStatus().equals("online")){
                  ((UserMain)mContext).connect(deviceDetails.get(position).getDeviceNo());
              }
          }
      });
  }
  

  I tried using:

  mAdapter.notifyDataSetChanged();

  But it doesn't seem to help.
• android: Share internet on the p2p group

  I have an android phone with a wifi connection that creates a Wifi P2P group. So it will be the host of the group. I have another android phone which is a client of the group. It has the network name and the passworld using discovery services. So he can connect to the access point created by the host phone. Now, How can I share internet connection from the host phone to the client phone? I know that some apps are able to do it such as netshare. I think they are using a VPN routing but how does they do that (programmatically of course)? Do you have an idea?
• WIFI Direct - Device1 Can find Device2 but Device2 can't find Device1

  I'm trying to connect two devices with wifi p2p. Two of my devices are 1. Xiaomi mi5 2. Onplus 3T

  I implemented the broadcast receiver and the main activity as shown here I ran the app, press discover on both the devices and device 1 discovers device 2 and displays the name but device2 can't find anything. I tried pressing the discover button one after another but it didn't help. What can go wrong? Is it possible that device2 doesn't support wifi direct? But from the settings app, in the wifi direct settings, they both can find each other. What am I doing wrong?