Inside the BluetoothGattCallback method onConnectionStateChange I am checking for the successful connection with the BLE device and calling the discoverServices method afterwards. The BLE device needs a pin entry (prompt by Android) for an successful pairing. I want to discover all available services immediately after connecting to the device because when switching to the main activity of the application there should be data from the available characteristics already displayed.
I tried to analyze the functionality of the onConnectionStateChange method and the behavior of the BLE device with pin. Unfortunately the method is called once you initialize the connection and again after successfully entering the pin. There isn't a difference within the receiving state codes. Status and newState are exactly the same when initializing and after successful pin entry and connection. Therefore i added this workaround with the Thread.sleep method to wait for the user entry of the pin and call afterwards the discoverServices method. But this workaround is not very practical because the user need to enter the pin within these 10 seconds. If not the connection is successful but the services won't be discovered.
How can i check or differ between these two states? Initializing the connection and successful enter of the pin?
@Override
public void onConnectionStateChange(BluetoothGatt gatt, int status, int newState) {
Log.d("KOPPLUNG", "In onConnectionStateChange with status: " + status + " and newState: " + newState);
if (newState == BluetoothProfile.STATE_CONNECTED) {
broadcastUpdate(ACTION_GATT_CONNECTED, mCallbackBleAddress);
Log.i(TAG, "Connected to GATT server." + mCallbackBleAddress);
// Attempts to discover services after successful connection.
try {
Thread.sleep(10000);
} catch (Exception e) {
}
for(int i = 0; i<5; i++){
if(mBoltDeviceHandler.getBoltDevice(mCallbackBleAddress).getBluetoothGatt().discoverServices()){
Log.i(TAG, "Attempting to start service discovery:" + true);
break;
}
}
} else if (newState == BluetoothProfile.STATE_DISCONNECTED) {
switch (status){
case 0: Log.i(TAG, "Sucessfully Disconnected from GATT server.");
break;
case 133: // Handle internal Android Bug
Log.i(TAG, "Connection aborted, Android Error 133");
broadcastUpdate(ACTION_GATT_CONNECTION_NOT_SUCCESSFUL, mCallbackBleAddress);
break;
default: Log.i(TAG, "Unexpected Disconnection from GATT server. Errorcode: "+status);
broadcastUpdate(ACTION_GATT_DISCONNECTED, mCallbackBleAddress);
autoconnect(gatt.getDevice());
}
Addition
The code for building up the connection is divided up in three different classes. The application starts with an scan activity where available devices are being searched and listed. By clicking on one list item (device) the connection process will be started.
onListItemClick
@Override
protected void onListItemClick(ListView l, View v, int position, long id) {
final BluetoothDevice device = mLeDeviceListAdapter.getDevice(position);
if (device == null) return;
Context mContext = getApplicationContext();
BoltDevice boltDevice = new BoltDevice(device,mContext);
int i = mBoltDeviceHandler.addBoltDevice(boltDevice);
Intent resultIntent = new Intent();
resultIntent.putExtra("IN_CONNECTION", boltDevice.getBleAddress());
resultIntent.putExtra("POSITION",i);
if(i != -1){
setResult(Activity.RESULT_OK, resultIntent);
}
else {
setResult(Activity.RESULT_CANCELED, resultIntent);
}
finish();
}
By running the above code an object from type BoltDevice is being created and added to the BoltDeviceHandler.
Relevant code from BoltDevice class
public BoltDevice(BluetoothDevice device, Context context) {
mContext = context;
this.mBluetoothDevice = device;
this.mBleAddress = device.getAddress();
this.mDeviceName = device.getName();
mBatteryLevel = 0;
mSpecialBolt = false;
//Workarround for 133 error taken from: https://github.com/googlesamples/android-BluetoothLeGatt/issues/44
mStartGattHandler.postDelayed(mStartGattRunnable, START_GATT_DELAY);
}
public void closeGatt() {
if (mBluetoothGatt != null) {
mBluetoothGatt.disconnect();
mBluetoothGatt.close();
mBluetoothGatt = null;
}
}
public boolean connect() {
// Previously connected device. Try to reconnect.
if (mBluetoothGatt != null) {
Log.d(TAG, "Trying to connect with existing bluetoothGATT to: " + mBleAddress);
if (mBluetoothGatt.connect()) {
return true;
} else {
Log.d(TAG, "Could not connect to existing bluetoothGATT: " + mBleAddress);
return false;
}
}
// We want to directly connect to the device, so we are setting the autoConnect
// parameter to false.
mBluetoothLeService.connect(mBluetoothDevice);
Log.d(TAG, "Trying to create a new connection to: " + mBluetoothDevice.getAddress());
return true;
}
public boolean disconnect() {
if (mBluetoothGatt != null) {
mBluetoothGatt.disconnect();
return true;
} else {
return false;
}
}
public void bindService(){
Intent gattServiceIntent = new Intent(mContext, BluetoothLeService.class);
}
Relevant code from the MainActivity (active after the ScanActivity is finished)
@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
switch(requestCode) {
case (5) : {
if (resultCode == Activity.RESULT_OK) {
int i = data.getIntExtra("POSITION",-1);
mReconnect[i] = false;
runOnUiThread(new Runnable() {
@Override
public void run() {
if(!isFinishing()) {
updateText(i,true);
ToastCompat.makeText(MainActivity.this, "In Connection!", ToastCompat.LENGTH_SHORT).show();
}
}
});
}
if (resultCode == Activity.RESULT_CANCELED) {
if(data!=null) {
int i = mBoltDeviceHandler.getBoltDevicePositionInList(data.getStringExtra("IN_CONNECTION"));
mReconnect[i] = true;
runOnUiThread(new Runnable() {
@Override
public void run() {
if(!isFinishing()) {
ToastCompat.makeText(MainActivity.this, "In Connection!", ToastCompat.LENGTH_SHORT).show();
}
}
});
}
else{
ToastCompat.makeText(this,"No device selected!", ToastCompat.LENGTH_SHORT).show();
}
}
break;
}
}
}
(...)
private final BroadcastReceiver mGattUpdateReceiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
final String action = intent.getAction();
final String address = intent.getStringExtra(BluetoothLeService.EXTRA_ADDRESS);
if (BluetoothLeService.ACTION_GATT_CONNECTED.equals(action)) {
ToastCompat.makeText(MainActivity.this, mBoltDeviceHandler.getBoltDevice(address).getDeviceName() + " " + getResources().getString(R.string.BLE_Connected), ToastCompat.LENGTH_SHORT).show();
updateText(mBoltDeviceHandler.getBoltDevicePositionInList(address), false);
ToastCompat.makeText(MainActivity.this, mBoltDeviceHandler.getBoltDevice(address).getDeviceName()+ ": "+ getResources().getString(R.string.BLE_ServicesDiscovered), ToastCompat.LENGTH_SHORT).show();
} else if (BluetoothLeService.ACTION_GATT_DISCONNECTED.equals(action)) {
(...)
