Writing data to Bluetooth LE characteristic in Android - android

Although similar questions have been asked but it's slightly different. I know how to pass data to a connected BLE device but I think I'm doing something wrong for which I need help.
The code below contains all the methods from my class that is extending BroadcastReceiver.
I scan and connect to a device specified by `PEN_ADDRESS`.
In `onServicesDiscovered` method I look for a service whose `UUID` contains `abcd`.
Then I loop through the characteristics of this services and look for three characteristics with specific strings in their `UUID`.
The third characteristic is a writable characteristic in which I'm trying to write data by calling the method `writeCharac(mGatt,writeChar1,123);`
The data `123` passed above is just a dummy data.
I debugged my code while trying writing to this characteristic but on putting breakpoints inside the writeCharac method, I found that the status value is false, indicating that the write was not successful.
Am I missing something here? Please do help!
public class BackgroundReceiverFire extends BroadcastReceiver {
Context context;
private BluetoothAdapter mBluetoothAdapter;
private BluetoothGatt mGatt;
private BluetoothLeService mBluetoothLeService;
private boolean mScanning;
private final String TAG = "READING: ";
private BluetoothDevice mDevice;
private Handler mHandler;
private static final int REQUEST_ENABLE_BT = 1;
private final String PEN_ADDRESS = "FB:23:AF:42:5C:56";
// Stops scanning after 10 seconds.
private static final long SCAN_PERIOD = 10000;
public void onReceive(Context context, Intent intent) {
this.context = context;
Toast.makeText(context, "Started Scanning", LENGTH_SHORT).show();
initializeBluetooth();
startScan();
}
private void initializeBluetooth() {
mHandler = new Handler();
// Use this check to determine whether BLE is supported on the device. Then you can
// selectively disable BLE-related features.
// Initializes a Bluetooth adapter. For API level 18 and above, get a reference to
// BluetoothAdapter through BluetoothManager.
final BluetoothManager bluetoothManager =
(BluetoothManager) context.getSystemService(Context.BLUETOOTH_SERVICE);
mBluetoothAdapter = bluetoothManager.getAdapter();
// Checks if Bluetooth is supported on the device.
if (mBluetoothAdapter == null) {
Toast.makeText(this.context, "No Bluetooth", LENGTH_SHORT).show();
return;
}
}
private void startScan() {
scanLeDevice(true);
}
private void stopScan() {
scanLeDevice(false);
}
private void scanLeDevice(final boolean enable) {
if (enable) {
// Stops scanning after a pre-defined scan period.
mHandler.postDelayed(new Runnable() {
#Override
public void run() {
mScanning = false;
mBluetoothAdapter.stopLeScan(mLeScanCallback);
}
}, SCAN_PERIOD);
mScanning = true;
//Scanning for the device
mBluetoothAdapter.startLeScan(mLeScanCallback);
} else {
mScanning = false;
mBluetoothAdapter.stopLeScan(mLeScanCallback);
}
}
private BluetoothAdapter.LeScanCallback mLeScanCallback =
new BluetoothAdapter.LeScanCallback() {
#Override
public void onLeScan(final BluetoothDevice device, int rssi, byte[] scanRecord) {
if (device.getAddress().matches(PEN_ADDRESS)) {
connectBluetooth(device);
Toast.makeText(context, "Device Found: " + device.getAddress(), Toast.LENGTH_LONG).show();
}
}
};
private void connectBluetooth(BluetoothDevice insulinPen) {
if (mGatt == null) {
Log.d("connectToDevice", "connecting to device: " + insulinPen.toString());
mDevice = insulinPen;
mGatt = insulinPen.connectGatt(context, true, gattCallback);
scanLeDevice(false);// will stop after first device detection
}
}
private void enableBluetooth() {
if (!mBluetoothAdapter.isEnabled()) {
mBluetoothAdapter.enable();
}
scanLeDevice(true);
}
private void disableBluetooth() {
if (mBluetoothAdapter.isEnabled()) {
mBluetoothAdapter.disable();
}
}
private final BluetoothGattCallback gattCallback = new BluetoothGattCallback() {
#Override
public void onConnectionStateChange(BluetoothGatt gatt, int status, int newState) {
Log.i("onConnectionStateChange", "Status: " + status);
switch (newState) {
case BluetoothProfile.STATE_CONNECTED:
gatt.discoverServices();
break;
case BluetoothProfile.STATE_DISCONNECTED:
Log.e("gattCallback", "STATE_DISCONNECTED");
Log.i("gattCallback", "reconnecting...");
BluetoothDevice mDevice = gatt.getDevice();
mGatt = null;
connectBluetooth(mDevice);
break;
default:
Log.e("gattCallback", "STATE_OTHER");
break;
}
}
public void onServicesDiscovered(BluetoothGatt gatt, int status) {
mGatt = gatt;
List<BluetoothGattService> services = mGatt.getServices();
Log.i("onServicesDiscovered", services.toString());
Iterator<BluetoothGattService> serviceIterator = services.iterator();
while(serviceIterator.hasNext()){
BluetoothGattService bleService = serviceIterator.next();
if(bleService.getUuid().toString().contains("abcd")){
//Toast.makeText(context,"Got the service",Toast.LENGTH_SHORT);
BluetoothGattCharacteristic readChar1 = bleService.getCharacteristics().get(0);
for (BluetoothGattDescriptor descriptor : readChar1.getDescriptors()) {
descriptor.setValue(BluetoothGattDescriptor.ENABLE_INDICATION_VALUE);
mGatt.writeDescriptor(descriptor);
mGatt.setCharacteristicNotification(readChar1, true);
}
//mGatt.readCharacteristic(readChar1);
BluetoothGattCharacteristic readChar2 = bleService.getCharacteristics().get(1);
for (BluetoothGattDescriptor descriptor : readChar2.getDescriptors()) {
descriptor.setValue(BluetoothGattDescriptor.ENABLE_INDICATION_VALUE);
mGatt.writeDescriptor(descriptor);
mGatt.setCharacteristicNotification(readChar2, true);
}
//mGatt.readCharacteristic(readChar2);
BluetoothGattCharacteristic writeChar1 = bleService.getCharacteristics().get(2);
for (BluetoothGattDescriptor descriptor : writeChar1.getDescriptors()) {
descriptor.setValue( BluetoothGattDescriptor.ENABLE_INDICATION_VALUE);
mGatt.writeDescriptor(descriptor);
mGatt.setCharacteristicNotification(writeChar1, true);
}
writeCharac(mGatt,writeChar1,123);
}
}
//gatt.readCharacteristic(therm_char);
}
public void writeCharac(BluetoothGatt gatt, BluetoothGattCharacteristic charac, int value ){
if (mBluetoothAdapter == null || gatt == null) {
Log.w(TAG, "BluetoothAdapter not initialized");
return;
}
/*
BluetoothGattCharacteristic charac = gattService
.getCharacteristic(uuid);
*/
if (charac == null) {
Log.e(TAG, "char not found!");
}
int unixTime = value;
String unixTimeString = Integer.toHexString(unixTime);
byte[] byteArray = hexStringToByteArray(unixTimeString);
charac.setValue(byteArray);
boolean status = mGatt.writeCharacteristic(charac);
if(status){
Toast.makeText(context,"Written Successfully",Toast.LENGTH_SHORT).show();
}else{
Toast.makeText(context,"Error writing characteristic",Toast.LENGTH_SHORT).show();
}
}
public byte[] hexStringToByteArray(String s) {
int len = s.length();
byte[] data = new byte[len/2];
for(int i = 0; i < len; i+=2){
data[i/2] = (byte) ((Character.digit(s.charAt(i), 16) << 4) + Character.digit(s.charAt(i+1), 16));
}
return data;
}
public void onCharacteristicRead(BluetoothGatt gatt,
BluetoothGattCharacteristic
characteristic, int status) {
Log.i("onCharacteristicRead", characteristic.toString());
String characteristicValue = characteristic.getValue().toString();
Log.d("CHARACTERISTIC VALUE: ", characteristicValue);
gatt.disconnect();
}
public void onCharacteristicChanged(BluetoothGatt gatt,
BluetoothGattCharacteristic
characteristic) {
String value = characteristic.getValue().toString();
Log.d(TAG,value);
}
};

Although the BLE API is asynchronous in nature, the actual signal transmission is inevitably synchronous. You have to wait for the previous connect/write/read call to callback before starting any connecting/writing/reading operation.
In your code onServicesDiscovered(BluetoothGatt gatt, int status) function, you called mGatt.writeDescriptor(descriptor) twice before trying to write the characteristic. The API will refuse to start your write request as it is being busy writing the descriptor, and return false for your mGatt.writeCharacteristic(charac) call.
So just wait for the writeDescriptor to callback before calling writeCharacteristic. This nature is not well documented but you can find some source here and here.

Thanks #reTs and #pooja for suggestions. The issue was due to these two lines
mGatt = nullconnectBluetooth(mDevice);
in STATE_DISCONNECTED. I had figured it out but don't remember the exact reason. Posting it just in case it is helpful.

Related

Obtain notifications from Bluetooth Gatt Characteristic

I'm currently trying to connect to this device Micro:bit. This device has multiple services and characteristics. The problem is that once connected, the device only returns 1 service and 0 characteristics. What I'm missing?
public class MainActivity extends Activity {
private BluetoothAdapter bleAdapter;
private BluetoothGattCharacteristic UART;
private BluetoothGattDescriptor descriptor;
private TextView connectionState;
private final UUID SERVICE = UUID.fromString("6E400001-B5A3-F393-E0A9-E50E24DCCA9E");
private final UUID CHARACTERISTIC = UUID.fromString("6E400003-B5A3-F393-E0A9-E50E24DCCA9E");
private final UUID CONFIG_DESCRIPTOR = UUID.fromString("00002902-0000-1000-8000-00805f9b34fb");
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Check if the system supports Bluetooth Low Energy
if (!getPackageManager().hasSystemFeature(PackageManager.FEATURE_BLUETOOTH_LE)) {
Toast.makeText(this, "BLE Not Supported", Toast.LENGTH_SHORT).show();
finish();
}
// Take the system BLE adapter
bleAdapter = ((BluetoothManager) getSystemService(BLUETOOTH_SERVICE)).getAdapter();
// Enable Bluetooth in case it's off.
if (bleAdapter == null || !bleAdapter.isEnabled()) {
Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableBtIntent, 1);
}
// Get paired devices.
Set<BluetoothDevice> pairedDevices = bleAdapter.getBondedDevices();
for (BluetoothDevice device : pairedDevices) {
// Connect to Micro:Bit (the only one paired device)
device.connectGatt(this, true, new BluetoothGattCallback() {
// Check if it connects or disconnects from the Micro:Bit
#Override
public void onConnectionStateChange(BluetoothGatt gatt, int status, int newState) {
super.onConnectionStateChange(gatt, status, newState);
switch (newState) {
case BluetoothProfile.STATE_CONNECTED:
gatt.discoverServices();
runOnUiThread(new Runnable() {
public void run() {
connectionState = findViewById(R.id.state);
connectionState.setText("Connected = True");
connectionState.setTextColor(Color.GREEN);
}
});
break;
case BluetoothProfile.STATE_DISCONNECTED:
gatt.disconnect();
runOnUiThread(new Runnable() {
public void run() {
connectionState = findViewById(R.id.state);
connectionState.setText("Connected = False");
connectionState.setTextColor(Color.RED);
}
});
}
}
#Override
public void onServicesDiscovered(BluetoothGatt gatt, int status) {
super.onServicesDiscovered(gatt, status);
List<BluetoothGattService> list = new ArrayList<BluetoothGattService>();
list = gatt.getServices();
for (BluetoothGattService elem : list){
Log.i("Service", elem.getUuid().toString());
List<BluetoothGattCharacteristic> list2 = new ArrayList<BluetoothGattCharacteristic>();
list2 = elem.getCharacteristics();
for (BluetoothGattCharacteristic elem2: list2) {
Log.i("Characteristic", elem2.getUuid().toString());
}
}
// Try to set notifications
UART = gatt.getService(SERVICE).getCharacteristic(CHARACTERISTIC);
gatt.setCharacteristicNotification(UART,true);
descriptor = UART.getDescriptor(CONFIG_DESCRIPTOR);
descriptor.setValue(BluetoothGattDescriptor.ENABLE_NOTIFICATION_VALUE);
gatt.writeDescriptor(descriptor);
}
// Activate every time UART Characteristic is updated
#Override
public void onCharacteristicChanged(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic) {
super.onCharacteristicChanged(gatt, characteristic);
runOnUiThread(new Runnable() {
public void run() {
TextView x = (TextView) findViewById(R.id.x_axis);
TextView y = (TextView) findViewById(R.id.y_axis);
TextView z = (TextView) findViewById(R.id.z_axis);
x.setText("HELLO");
y.setText("IT ");
z.setText("WORKS!");
}
});
}
});
}
}
}
The UUID from the variables SERVICE and CHARACTERISTIC are from here. I try to connect to that UART Service and get notifications when this device updates the TX Characteristic. But I'm just obtaining 1 service on the loop from onServicesDiscovered() and I get null pointer if I try to gatt.getService(SERVICE).getCharacteristic(CHARACTERISTIC). What I'm doing wrong?

BLE Services never discovered

I want to send a message to a BLE device. In my understanding one first has to discover the devices services and then send the message to a service characteristic. So here is what I did:
public class BluetoothLeService extends Service {
private BluetoothManager mBluetoothManager;
private BluetoothAdapter mBluetoothAdapter;
private String mBluetoothDeviceAddress;
private BluetoothGatt mBluetoothGatt;
private String macAddress;
private String serviceUuid;
private String characteristicUuid;
private Application app;
private int transmissionValue = 450;
public BluetoothLeService(String address, String serviceUuid, String characteristicUuid) {
this.macAddress = address;
this.serviceUuid = serviceUuid;
this.characteristicUuid = characteristicUuid;
}
private final BluetoothGattCallback mGattCallback = new BluetoothGattCallback() {
#Override
public void onConnectionStateChange(BluetoothGatt gatt, int status, int newState) {
System.out.println("connectionStateChange: " + status);
if (STATE_CONNECTED == newState) {
gatt.discoverServices();
}
}
#Override
public void onServicesDiscovered(BluetoothGatt gatt, int status) {
if(gatt.getDevice().getName().equals("MyDeviceName")) {
sendMessageAfterDiscovery(gatt);
}
}
};
public boolean initialize(Application app) {
this.app = app;
if (mBluetoothManager == null) {
mBluetoothManager = (BluetoothManager) app.getSystemService(Context.BLUETOOTH_SERVICE);
if (mBluetoothManager == null) {
return false;
}
}
mBluetoothAdapter = mBluetoothManager.getAdapter();
if (mBluetoothAdapter == null) {
return false;
}
return true;
}
public boolean connect() {
return connect(macAddress);
}
public boolean connect(final String address) {
this.macAddress = address;
if (mBluetoothAdapter == null || macAddress == null) {
return false;
}
final BluetoothDevice device = mBluetoothAdapter.getRemoteDevice(macAddress);
if (device == null) {
Log.w(TAG, "Device not found. Unable to connect.");
return false;
}
mBluetoothGatt = device.connectGatt(this, false, mGattCallback);
return true;
}
public void writeCharacteristic(int value) {
this.transmissionValue = value;
BluetoothDevice mDevice = mBluetoothAdapter.getRemoteDevice(this.macAddress);
BluetoothGatt mBG = mDevice.connectGatt(app.getApplicationContext(), true, mGattCallback);
System.out.println("device name: " + mBG.getDevice().getName());
}
private void sendMessageAfterDiscovery(BluetoothGatt gatt) {
BluetoothGattService mSVC = gatt.getService(UUID.fromString(serviceUuid));
BluetoothGattCharacteristic mCH = mSVC.getCharacteristic(UUID.fromString(characteristicUuid));
mCH.setValue(transmissionValue, BluetoothGattCharacteristic.FORMAT_UINT16, 0);
System.out.println("characteristic writable: " + isCharacteristicWriteable(mCH));
System.out.println("success? " + gatt.writeCharacteristic(mCH));
}
public static boolean isCharacteristicWriteable(BluetoothGattCharacteristic pChar) {
return (pChar.getProperties() & (BluetoothGattCharacteristic.PROPERTY_WRITE | BluetoothGattCharacteristic.PROPERTY_WRITE_NO_RESPONSE)) != 0;
}
}
And here is the code where I want to send the message:
private void sendMessage() {
BluetoothLeService ble = new BluetoothLeService("B0:00:00:00:00:C0", "0000fff0-1111-0000-0000-00805f9b34fb","0000fff1-1111-0000-0000-00805f9b34fb");
ble.initialize(app);
ble.connect();,
ble.writeCharacteristic(450)
}
Now whenever I want to connect to the device and send a message to it, the onServiceDiscovered method is never called although the device is recognized because I can get the name of the device. Also no error is thrown.
Why is this method never called? Am I doing something wrong?
I already checked the permissions and I added the class as a Service in the manifest.
Thanks for your help...
You need to call discoverServices from within the onConnectionStateChange method of your GATT callback. Documentation of the discoverServices method:
Discovers services offered by a remote device as well as their
characteristics and descriptors.
This is an asynchronous operation. Once service discovery is
completed, the onServicesDiscovered(BluetoothGatt, int) callback is
triggered. If the discovery was successful, the remote services can be
retrieved using the getServices() function.
In your case, updating your code as follows should do the trick:
#Override
public void onConnectionStateChange(BluetoothGatt gatt, int status, int newState) {
System.out.println("connectionStateChange: " + status);
if (STATE_CONNECTED == newState) {
gatt.discoverServices();
}
}

Using BLE - Read GATT characteristics

I'm trying to read GATT characteristic values from a Bluetooth LE device (a Heart Rate bracelet). Its specs are:
Services
Characteristics
I have not yet figured out how to "read" the specifications and "translate" them into code.
I need to show on my app the heartbeats detected by the device. What is the way to read the GATT values? A code example would be much appreciated :)
Follow my actual source code.
SETUP THE BLUETOOT CONNECTION
private BluetoothAdapter mBluetoothAdapter;
private BluetoothGatt mBluetoothGatt;
private Handler mHandler;
private static final int REQUEST_ENABLE_BT = 1;
private static final long SCAN_PERIOD = 10000;
// ...
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_bluetooth);
mHandler = new Handler();
// BLE is supported?
if (!getPackageManager().hasSystemFeature(PackageManager.FEATURE_BLUETOOTH_LE)) {
Toast.makeText(this, "Bluetooth Low Energy non supportato", Toast.LENGTH_SHORT).show();
finish();
}
final BluetoothManager bluetoothManager = (BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE);
mBluetoothAdapter = bluetoothManager.getAdapter();
// Bluetooth is supported?
if (mBluetoothAdapter == null) {
Toast.makeText(this, "Bluetooth non supportato", Toast.LENGTH_SHORT).show();
finish();
}
}
#Override
protected void onResume() {
super.onResume();
// Bluetooth is enabled?
if (!mBluetoothAdapter.isEnabled()) {
Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
}
scanLeDevice(true);
}
#Override
protected void onPause() {
super.onPause();
if (mBluetoothAdapter != null && mBluetoothAdapter.isEnabled()) {
scanLeDevice(false);
}
}
DISCOVER BLE DEVICES AND CONNECT WITH HEART RATE MONITOR
// Device scan callback.
private BluetoothAdapter.LeScanCallback mLeScanCallback =
new BluetoothAdapter.LeScanCallback() {
#Override
public void onLeScan(final BluetoothDevice device, int rssi, byte[] scanRecord) {
runOnUiThread(new Runnable() {
#Override
public void run() {
Log.i(TAG, "Name: " + device.getName() + " (" + device.getAddress() + ")");
String deviceAddress = device.getAddress();
if (deviceAddress.equals("C0:19:37:54:9F:30")) {
connectToDevice(device);
}
}
});
}
};
public void connectToDevice(BluetoothDevice device) {
if (mBluetoothGatt == null) {
Log.i(TAG, "Attempting to connect to device " + device.getName() + " (" + device.getAddress() + ")");
mBluetoothGatt = device.connectGatt(this, true, gattCallback);
scanLeDevice(false);// will stop after first device detection
}
}
private final BluetoothGattCallback gattCallback = new BluetoothGattCallback() {
#Override
public void onConnectionStateChange(BluetoothGatt gatt, int status, int newState) {
Log.i(TAG, "Status: " + status);
switch (newState) {
case BluetoothProfile.STATE_CONNECTED:
Log.i(TAG, "STATE_CONNECTED");
//BluetoothDevice device = gatt.getDevice(); // Get device
gatt.discoverServices();
break;
case BluetoothProfile.STATE_DISCONNECTED:
Log.e(TAG, "STATE_DISCONNECTED");
break;
default:
Log.e(TAG, "STATE_OTHER");
}
}
#Override
public void onServicesDiscovered(BluetoothGatt gatt, int status) {
List<BluetoothGattService> services = gatt.getServices();
Log.i(TAG, "Services: " + services.toString());
BluetoothGattCharacteristic bpm = services.get(2).getCharacteristics().get(0);
gatt.readCharacteristic(services.get(0).getCharacteristics().get(0));
}
#Override
public void onCharacteristicRead(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic, int status) {
// my attempt to read and print characteristics
byte[] charValue = characteristic.getValue();
byte flag = charValue[0];
Log.i(TAG, "Characteristic: " + flag);
//gatt.disconnect();
}
};
try with this inside gattCallback:
#Override
public synchronized void onCharacteristicChanged(BluetoothGatt gatt,
BluetoothGattCharacteristic characteristic) {
final byte[] dataInput = characteristic.getValue();
}
EDIT
And I think you are going to receive a byte with the hear rate data, use this function to get the int value:
public int unsignedByteToInt(byte b) {
return b & 0xFF;
}
And call it inside onCharacteristicChanged():
final byte[] dataInput = characteristic.getValue();
int hearRate = unsignedByteToInt(dataInput);
EDIT 2
Create a notification listener for the heart rate:
public void setHeartRateNotification(boolean enable){
String uuidHRCharacteristic = "YOUR CHARACTERISTIC";
BluetoothGattService mBluetoothLeService = null;
BluetoothGattCharacteristic mBluetoothGattCharacteristic = null;
for (BluetoothGattService service : mBluetoothGatt.getServices()) {
if ((service == null) || (service.getUuid() == null)) {
continue;
}
if (uuidAccelService.equalsIgnoreCase(service.getUuid().toString())) {
mBluetoothLeService = service;
}
}
if(mBluetoothLeService!=null) {
mBluetoothGattCharacteristic =
mBluetoothLeService.getCharacteristic(UUID.fromString(uuidHRCharacteristic));
}
else{
Log.i("Test","mBluetoothLeService is null");
}
if(mBluetoothGattCharacteristic!=null) {
setCharacteristicNotification(mBluetoothGattCharacteristic, enable);
Log.i("Test","setCharacteristicNotification:"+true);
}
else{
Log.i("Test","mBluetoothGattCharacteristic is null");
}
}
And set it onServiceDiscover inside gattCallback:
#Override
public void onServicesDiscovered(BluetoothGatt gatt, int status) {
Log.i("Test", "onServicesDiscovered received: " + status);
setHeartRateNotification(true);
}

how to connect to Bluetooth Low Energy Device

hi everyone i am working on android app which requires connecting to ble device and sending data over ble. i have tried scanning and displaying the scanned devices on a list which works fine. the problem is with connecting to the scanned device. here is the part of my main activity code.
public class main_activity extends Activity implements BluetoothLeUart.Callback{
public ImageButton fabbutton;
Activity activity;
private ArrayAdapter<String> adapter;
private ArrayList<String> liste,devicedata;
private ListView list;
public EditText input;
String name,address,Devicename,Deviceaddress,datadevicename;
private BluetoothGatt mBluetoothGatt;
public static String SelectedDeviceName;
private BluetoothAdapter mBluetoothAdapter;
public ArrayList<BluetoothDevice> dev;
private Handler mHandler;
private static final int REQUEST_ENABLE_BT = 1;
private static final long SCAN_PERIOD = 10000;
BluetoothLeUart uart = new BluetoothLeUart(this);
public static BluetoothDevice device;
private BluetoothGatt mGatt;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main_activity);
fabbutton = (ImageButton) findViewById(R.id.fabbutton);
activity = this;
mHandler = new Handler();
final BluetoothManager bluetoothManager = (BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE);
mBluetoothAdapter = bluetoothManager.getAdapter();
scanLeDevice(true);
mActionBar.setTitle(Html.fromHtml("<font color='#727272'>Board List</font>"));
list = (ListView) findViewById(R.id.list);
liste = new ArrayList<String>();
liste.clear();
adapter = new ArrayAdapter<String>(list.getContext(), android.R.layout.simple_list_item_1, liste);
list.setAdapter(adapter);
// On Click Listener for Paired BLE Device List
list.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
SelectedDeviceName = list.getItemAtPosition(position).toString();
String[] splitString = SelectedDeviceName.split(" ");
Devicename = splitString[0];
Deviceaddress = splitString[1];
device = mBluetoothAdapter.getRemoteDevice(Deviceaddress);
Toast.makeText(getApplicationContext(),device.toString(),Toast.LENGTH_SHORT).show();
//device.connectGatt(getApplicationContext(), true, gattCallback);
uart.connectFirstAvailable();// this is where i start connecting process.
}
});
here is the code of my BluetoothLeUart class
public class BluetoothLeUart extends BluetoothGattCallback implements BluetoothAdapter.LeScanCallback {
public String mDeviceAddress;
// UUIDs for UART service and associated characteristics.
public static UUID UART_UUID = UUID.fromString("6E400001-B5A3-F393-E0A9-E50E24DCCA9E");
public static UUID TX_UUID = UUID.fromString("6E400002-B5A3-F393-E0A9-E50E24DCCA9E");
public static UUID RX_UUID = UUID.fromString("6E400003-B5A3-F393-E0A9-E50E24DCCA9E");
// UUID for the UART BTLE client characteristic which is necessary for notifications.
public static UUID CLIENT_UUID = UUID.fromString("00002902-0000-1000-8000-00805f9b34fb");
// UUIDs for the Device Information service and associated characeristics.
public static UUID DIS_UUID = UUID.fromString("0000180a-0000-1000-8000-00805f9b34fb");
public static UUID DIS_MANUF_UUID = UUID.fromString("00002a29-0000-1000-8000-00805f9b34fb");
public static UUID DIS_MODEL_UUID = UUID.fromString("00002a24-0000-1000-8000-00805f9b34fb");
public static UUID DIS_HWREV_UUID = UUID.fromString("00002a26-0000-1000-8000-00805f9b34fb");
public static UUID DIS_SWREV_UUID = UUID.fromString("00002a28-0000-1000-8000-00805f9b34fb");
// Internal UART state.
private Context context;
private WeakHashMap<Callback, Object> callbacks;
private BluetoothAdapter adapter;
private BluetoothGatt gatt;
private BluetoothGattCharacteristic tx;
private BluetoothGattCharacteristic rx;
private boolean connectFirst;
private boolean writeInProgress; // Flag to indicate a write is currently in progress
// Device Information state.
private BluetoothGattCharacteristic disManuf;
private BluetoothGattCharacteristic disModel;
private BluetoothGattCharacteristic disHWRev;
private BluetoothGattCharacteristic disSWRev;
private boolean disAvailable;
// Queues for characteristic read (synchronous)
private Queue<BluetoothGattCharacteristic> readQueue;
// Interface for a BluetoothLeUart client to be notified of UART actions.
public interface Callback {
public void onConnected(BluetoothLeUart uart);
public void onConnectFailed(BluetoothLeUart uart);
public void onDisconnected(BluetoothLeUart uart);
public void onReceive(BluetoothLeUart uart, BluetoothGattCharacteristic rx);
public void onDeviceFound(BluetoothDevice device);
public void onDeviceInfoAvailable();
}
public BluetoothLeUart(Context context) {
super();
this.context = context;
this.callbacks = new WeakHashMap<Callback, Object>();
this.adapter = BluetoothAdapter.getDefaultAdapter();
this.gatt = null;
this.tx = null;
this.rx = null;
this.disManuf = null;
this.disModel = null;
this.disHWRev = null;
this.disSWRev = null;
this.disAvailable = false;
this.connectFirst = false;
this.writeInProgress = false;
this.readQueue = new ConcurrentLinkedQueue<BluetoothGattCharacteristic>();
}
// Return instance of BluetoothGatt.
public BluetoothGatt getGatt() {
return gatt;
}
// Return true if connected to UART device, false otherwise.
public boolean isConnected() {
return (tx != null && rx != null);
}
public String getDeviceInfo() {
if (tx == null || !disAvailable ) {
// Do nothing if there is no connection.
return "";
}
StringBuilder sb = new StringBuilder();
sb.append("Manufacturer : " + disManuf.getStringValue(0) + "\n");
sb.append("Model : " + disModel.getStringValue(0) + "\n");
sb.append("Firmware : " + disSWRev.getStringValue(0) + "\n");
return sb.toString();
};
public boolean deviceInfoAvailable() { return disAvailable; }
// Send data to connected UART device.
public void send(byte[] data) {
if (tx == null || data == null || data.length == 0) {
// Do nothing if there is no connection or message to send.
return;
}
// Update TX characteristic value. Note the setValue overload that takes a byte array must be used.
tx.setValue(data);
writeInProgress = true; // Set the write in progress flag
gatt.writeCharacteristic(tx);
// ToDo: Update to include a timeout in case this goes into the weeds
while (writeInProgress); // Wait for the flag to clear in onCharacteristicWrite
}
public void registerCallback(Callback callback) {
callbacks.put(callback, null);
}
public void unregisterCallback(Callback callback) {
callbacks.remove(callback);
}
// Disconnect to a device if currently connected.
public void disconnect() {
if (gatt != null) {
gatt.disconnect();
}
gatt = null;
tx = null;
rx = null;
}
// Stop any in progress UART device scan.
public void stopScan() {
if (adapter != null) {
adapter.stopLeScan(this);
}
}
// Start scanning for BLE UART devices. Registered callback's onDeviceFound method will be called
// when devices are found during scanning.
public void startScan() {
if (adapter != null) {
adapter.startLeScan(this);
Toast.makeText(context,"Entered",Toast.LENGTH_SHORT).show();
}
}
// Connect to the first available UART device.
public void connectFirstAvailable() {
// Disconnect to any connected device.
disconnect();
// Stop any in progress device scan.
stopScan();
// Start scan and connect to first available device.
connectFirst = true;
startScan();
}
// Handlers for BluetoothGatt and LeScan events.
#Override
public void onConnectionStateChange(BluetoothGatt gatt, int status, int newState) {
super.onConnectionStateChange(gatt, status, newState);
if (newState == BluetoothGatt.STATE_CONNECTED) {
if (status == BluetoothGatt.GATT_SUCCESS) {
// Connected to device, start discovering services.
if (!gatt.discoverServices()) {
// Error starting service discovery.
connectFailure();
}
}
else {
// Error connecting to device.
connectFailure();
}
}
else if (newState == BluetoothGatt.STATE_DISCONNECTED) {
// Disconnected, notify callbacks of disconnection.
rx = null;
tx = null;
notifyOnDisconnected(this);
}
}
#Override
public void onServicesDiscovered(BluetoothGatt gatt, int status) {
super.onServicesDiscovered(gatt, status);
// Notify connection failure if service discovery failed.
if (status == BluetoothGatt.GATT_FAILURE) {
connectFailure();
return;
}
// Save reference to each UART characteristic.
tx = gatt.getService(UART_UUID).getCharacteristic(TX_UUID);
rx = gatt.getService(UART_UUID).getCharacteristic(RX_UUID);
// Setup notifications on RX characteristic changes (i.e. data received).
// First call setCharacteristicNotification to enable notification.
if (!gatt.setCharacteristicNotification(rx, true)) {
// Stop if the characteristic notification setup failed.
connectFailure();
return;
}
// Next update the RX characteristic's client descriptor to enable notifications.
BluetoothGattDescriptor desc = rx.getDescriptor(CLIENT_UUID);
if (desc == null) {
// Stop if the RX characteristic has no client descriptor.
connectFailure();
return;
}
desc.setValue(BluetoothGattDescriptor.ENABLE_NOTIFICATION_VALUE);
if (!gatt.writeDescriptor(desc)) {
// Stop if the client descriptor could not be written.
connectFailure();
return;
}
// Notify of connection completion.
notifyOnConnected(this);
}
#Override
public void onCharacteristicChanged(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic) {
super.onCharacteristicChanged(gatt, characteristic);
notifyOnReceive(this, characteristic);
}
#Override
public void onCharacteristicRead (BluetoothGatt gatt, BluetoothGattCharacteristic characteristic, int status) {
super.onCharacteristicRead(gatt, characteristic, status);
if (status == BluetoothGatt.GATT_SUCCESS) {
//Log.w("DIS", characteristic.getStringValue(0));
// Check if there is anything left in the queue
BluetoothGattCharacteristic nextRequest = readQueue.poll();
if(nextRequest != null){
// Send a read request for the next item in the queue
gatt.readCharacteristic(nextRequest);
}
else {
// We've reached the end of the queue
disAvailable = true;
notifyOnDeviceInfoAvailable();
}
}
else {
//Log.w("DIS", "Failed reading characteristic " + characteristic.getUuid().toString());
}
}
#Override
public void onCharacteristicWrite(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic, int status) {
super.onCharacteristicWrite(gatt, characteristic, status);
if (status == BluetoothGatt.GATT_SUCCESS) {
// Log.d(TAG,"Characteristic write successful");
}
writeInProgress = false;
}
#Override
public void onLeScan(BluetoothDevice device, int rssi, byte[] scanRecord) {
Toast.makeText(context, "onLe Entered", Toast.LENGTH_SHORT).show();
if (!parseUUIDs(scanRecord).contains(UART_UUID)) {
return;
}
// Notify registered callbacks of found device.
notifyOnDeviceFound(device);
// Connect to first found device if required.
if (connectFirst) {
// Stop scanning for devices.
// Prevent connections to future found devices.
if (mDeviceAddress.equals(device.getAddress())) {
stopScan();
connectFirst = false;
// Connect to device.
gatt = device.connectGatt(context, true, this);
}
}
}
// Private functions to simplify the notification of all callbacks of a certain event.
private void notifyOnConnected(BluetoothLeUart uart) {
for (Callback cb : callbacks.keySet()) {
if (cb != null) {
cb.onConnected(uart);
}
}
}
private void notifyOnConnectFailed(BluetoothLeUart uart) {
for (Callback cb : callbacks.keySet()) {
if (cb != null) {
cb.onConnectFailed(uart);
}
}
}
private void notifyOnDisconnected(BluetoothLeUart uart) {
for (Callback cb : callbacks.keySet()) {
if (cb != null) {
cb.onDisconnected(uart);
}
}
}
private void notifyOnReceive(BluetoothLeUart uart, BluetoothGattCharacteristic rx) {
for (Callback cb : callbacks.keySet()) {
if (cb != null ) {
cb.onReceive(uart, rx);
}
}
}
private void notifyOnDeviceFound(BluetoothDevice device) {
for (Callback cb : callbacks.keySet()) {
if (cb != null) {
cb.onDeviceFound(device);
}
}
}
private void notifyOnDeviceInfoAvailable() {
for (Callback cb : callbacks.keySet()) {
if (cb != null) {
cb.onDeviceInfoAvailable();
}
}
}
// Notify callbacks of connection failure, and reset connection state.
private void connectFailure() {
rx = null;
tx = null;
notifyOnConnectFailed(this);
}
private List<UUID> parseUUIDs(final byte[] advertisedData) {
List<UUID> uuids = new ArrayList<UUID>();
int offset = 0;
while (offset < (advertisedData.length - 2)) {
int len = advertisedData[offset++];
if (len == 0)
break;
int type = advertisedData[offset++];
switch (type) {
case 0x02: // Partial list of 16-bit UUIDs
case 0x03: // Complete list of 16-bit UUIDs
while (len > 1) {
int uuid16 = advertisedData[offset++];
uuid16 += (advertisedData[offset++] << 8);
len -= 2;
uuids.add(UUID.fromString(String.format("%08x-0000-1000-8000-00805f9b34fb", uuid16)));
}
break;
case 0x06:// Partial list of 128-bit UUIDs
case 0x07:// Complete list of 128-bit UUIDs
// Loop through the advertised 128-bit UUID's.
while (len >= 16) {
try {
// Wrap the advertised bits and order them.
ByteBuffer buffer = ByteBuffer.wrap(advertisedData, offset++, 16).order(ByteOrder.LITTLE_ENDIAN);
long mostSignificantBit = buffer.getLong();
long leastSignificantBit = buffer.getLong();
uuids.add(new UUID(leastSignificantBit,
mostSignificantBit));
} catch (IndexOutOfBoundsException e) {
// Defensive programming.
//Log.e(LOG_TAG, e.toString());
continue;
} finally {
// Move the offset to read the next uuid.
offset += 15;
len -= 16;
}
}
break;
default:
offset += (len - 1);
break;
}
}
return uuids;
}
}
here is the code of my BluetoothLeService class
public class BluetoothLeService extends Service {
private final static String TAG = BluetoothLeService.class.getSimpleName();
private BluetoothManager mBluetoothManager;
private BluetoothAdapter mBluetoothAdapter;
private String mBluetoothDeviceAddress;
public BluetoothGatt mBluetoothGatt;
private int mConnectionState =STATE_DISCONNECTED;
private static final int STATE_DISCONNECTED = 0;
private static final int STATE_CONNECTING = 1;
private static final int STATE_CONNECTED = 2;
public final static String ACTION_GATT_CONNECTED =
"com.example.bluetooth.le.ACTION_GATT_CONNECTED";
public final static String ACTION_GATT_DISCONNECTED =
"com.example.bluetooth.le.ACTION_GATT_DISCONNECTED";
public final static String ACTION_GATT_SERVICES_DISCOVERED =
"com.example.bluetooth.le.ACTION_GATT_SERVICES_DISCOVERED";
public final static String ACTION_DATA_AVAILABLE =
"com.example.bluetooth.le.ACTION_DATA_AVAILABLE";
public final static String EXTRA_DATA =
"com.example.bluetooth.le.EXTRA_DATA";
// UUIDs for UART service and associated characteristics.
public static UUID UART_UUID = UUID.fromString("6E400001-B5A3-F393-E0A9-E50E24DCCA9E");
public static UUID TX_UUID = UUID.fromString("6E400002-B5A3-F393-E0A9-E50E24DCCA9E");
public static UUID RX_UUID = UUID.fromString("6E400003-B5A3-F393-E0A9-E50E24DCCA9E");
// UUID for the UART BTLE client characteristic which is necessary for notifications.
public static UUID CLIENT_UUID = UUID.fromString("00002902-0000-1000-8000-00805f9b34fb");
// UUIDs for the Device Information service and associated characeristics.
public static UUID DIS_UUID = UUID.fromString("0000180a-0000-1000-8000-00805f9b34fb");
public static UUID DIS_MANUF_UUID = UUID.fromString("00002a29-0000-1000-8000-00805f9b34fb");
public static UUID DIS_MODEL_UUID = UUID.fromString("00002a24-0000-1000-8000-00805f9b34fb");
public static UUID DIS_HWREV_UUID = UUID.fromString("00002a26-0000-1000-8000-00805f9b34fb");
public static UUID DIS_SWREV_UUID = UUID.fromString("00002a28-0000-1000-8000-00805f9b34fb");
// Implements callback methods for GATT events that the app cares about. For example,
// connection change and services discovered.
public final BluetoothGattCallback mGattCallback = new BluetoothGattCallback() {
#Override
public void onConnectionStateChange(BluetoothGatt gatt, int status, int newState) {
String intentAction;
if (newState == BluetoothProfile.STATE_CONNECTED) {
Log.i("STATE CONNECTED", "OK");
intentAction = ACTION_GATT_CONNECTED;
mConnectionState = STATE_CONNECTED;
broadcastUpdate(intentAction);
Log.i("STATE CONNECTED BROADCAST SENT - DISCOVERING SERVICES", "OK");
// Attempts to discover services after successful connection.
mBluetoothGatt.discoverServices();
Log.i("AFTER DISCOVER SERVICES", "OK");
} else if (newState == BluetoothProfile.STATE_DISCONNECTED) {
Log.i("STATE DISCONNECTED", "OK");
intentAction = ACTION_GATT_DISCONNECTED;
mConnectionState = STATE_DISCONNECTED;
Log.i(TAG, "Disconnected from GATT server.");
broadcastUpdate(intentAction);
Log.i("STATE DISCONNECTED BROADCAST SENT", "OK");
}
if(mConnectionState==123334){
}
}
#Override
public void onServicesDiscovered(BluetoothGatt gatt, int status) {
if (status == BluetoothGatt.GATT_SUCCESS) {
broadcastUpdate(ACTION_GATT_SERVICES_DISCOVERED);
Log.i("GATT SUCCESS - SERVICES DISCOVERED", "OK");
} else {
Log.w(TAG, "onServicesDiscovered received: " + status);
}
}
#Override
public void onCharacteristicRead(BluetoothGatt gatt,
BluetoothGattCharacteristic characteristic,
int status) {
if (status == BluetoothGatt.GATT_SUCCESS) {
broadcastUpdate(ACTION_DATA_AVAILABLE, characteristic);
}
}
#Override
public void onCharacteristicChanged(BluetoothGatt gatt,
BluetoothGattCharacteristic characteristic) {
broadcastUpdate(ACTION_DATA_AVAILABLE, characteristic);
}
};
private void broadcastUpdate(final String action) {
final Intent intent = new Intent(action);
sendBroadcast(intent);
Log.i("INTENT SENT", "OK");
}
private void broadcastUpdate(final String action, final BluetoothGattCharacteristic characteristic) {
final Intent intent = new Intent(action);
// For all other profiles, writes the data formatted in HEX.
final byte[] data = characteristic.getValue();
if (data != null && data.length > 0) {
final StringBuilder stringBuilder = new StringBuilder(data.length);
for(byte byteChar : data)
stringBuilder.append(String.format("%02X ", byteChar));
intent.putExtra(EXTRA_DATA, new String(data) + "\n" + stringBuilder.toString());
}
sendBroadcast(intent);
}
public class LocalBinder extends Binder {
public BluetoothLeService getService() {
return BluetoothLeService.this;
}
}
#Override
public IBinder onBind(Intent intent) {
return mBinder;
}
#Override
public boolean onUnbind(Intent intent) {
close();
return super.onUnbind(intent);
}
private final IBinder mBinder = new LocalBinder();
public boolean initialize() {
// For API level 18 and above, get a reference to BluetoothAdapter through
// BluetoothManager.
if (mBluetoothManager == null) {
mBluetoothManager = (BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE);
if (mBluetoothManager == null) {
Log.e(TAG, "Unable to initialize BluetoothManager.");
return false;
}
}
mBluetoothAdapter = mBluetoothManager.getAdapter();
if (mBluetoothAdapter == null) {
Log.e(TAG, "Unable to obtain a BluetoothAdapter.");
return false;
}
return true;
}
public boolean connect(final String address) {
if (mBluetoothAdapter == null || address == null) {
Log.w(TAG, "BluetoothAdapter not initialized or unspecified address.");
return false;
}
// Previously connected device. Try to reconnect.
if (mBluetoothDeviceAddress != null && address.equals(mBluetoothDeviceAddress)
&& mBluetoothGatt != null) {
Log.d(TAG, "Trying to use an existing mBluetoothGatt for connection.");
if (mBluetoothGatt.connect()) {
mConnectionState = STATE_CONNECTING;
return true;
} else {
return false;
}
}
final BluetoothDevice device = mBluetoothAdapter.getRemoteDevice(address);
if (device == null) {
Log.w(TAG, "Device not found. Unable to connect.");
return false;
}
// We want to directly connect to the device, so we are setting the autoConnect
// parameter to false.
mBluetoothGatt = device.connectGatt(this, false, mGattCallback);
Log.d(TAG, "Trying to create a new connection.");
mBluetoothDeviceAddress = address;
mConnectionState = STATE_CONNECTING;
return true;
}
public void disconnect() {
if (mBluetoothAdapter == null || mBluetoothGatt == null) {
Log.w(TAG, "BluetoothAdapter not initialized");
return;
}
mBluetoothGatt.disconnect();
}
public void close() {
if (mBluetoothGatt == null) {
return;
}
mBluetoothGatt.close();
mBluetoothGatt = null;
}
public void readCharacteristic(BluetoothGattCharacteristic characteristic) {
if (mBluetoothAdapter == null || mBluetoothGatt == null) {
Log.w(TAG, "BluetoothAdapter not initialized");
return;
}
mBluetoothGatt.readCharacteristic(characteristic);
}
public void setCharacteristicNotification(BluetoothGattCharacteristic characteristic,
boolean enabled) {
if (mBluetoothAdapter == null || mBluetoothGatt == null) {
Log.w(TAG, "BluetoothAdapter not initialized");
return;
}
mBluetoothGatt.setCharacteristicNotification(characteristic, enabled);
}
public List<BluetoothGattService> getSupportedGattServices() {
if (mBluetoothGatt == null) return null;
return mBluetoothGatt.getServices();
}
}
What is the target version of targetSdkVersion. I had similar issue and changed build.gradle to
defaultConfig {
applicationId "com.XXX.XXXr"
minSdkVersion 21
targetSdkVersion 22
versionCode 1
versionName "1.0"
}
It solved the problem, but I have some others needs to be solved...
In my case (Adafruit Feather BLE) the following worked
public static String LOG_TAG = "Adafruit Ind";
public static UUID UART_UUID = UUID.fromString("6e400001-b5a3-f393-e0a9-e50e24dcca9e");
public static UUID TX_UUID = UUID.fromString("6e400002-b5a3-f393-e0a9-e50e24dcca9e");
public static UUID RX_UUID = UUID.fromString("6e400003-b5a3-f393-e0a9-e50e24dcca9e");
public static UUID CLIENT_UUID = UUID.fromString("00002902-0000-1000-8000-00805F9B34FB");
public static UUID DIS_UUID = UUID.fromString("000001530-1212-EFDE-1523-785FEABCD123");
public static UUID DIS_MANUF_UUID = UUID.fromString("00002A29-0000-1000-8000-00805F9B34FB");
public static UUID DIS_MODEL_UUID = UUID.fromString("00002A24-0000-1000-8000-00805F9B34FB");
public static UUID DIS_HWREV_UUID = UUID.fromString("00002A26-0000-1000-8000-00805F9B34FB");
public static UUID DIS_SWREV_UUID = UUID.fromString("00002A28-0000-1000-8000-00805F9B34FB");

What are the steps to get notified by Bluetooth Low Energy (BLE) device?

I am working on a Bluetooth Low Energy (BLE) app. I have a BLE device (scale) which measures weight. I am able to connect with this device. But I am not getting how to read data (weight value) from it.
I want to know if my app is connected to any BLE device, so what are the steps to get notified by device in order to get updated data.
Okay, following is the for my Activity which I am using..
public class BlogBLEActivity extends Activity implements OnItemClickListener
{
private final static String TAG = BlogBLEActivity.class.getSimpleName();
private BluetoothAdapter bluetoothAdapter;
BluetoothManager bluetoothManager;
boolean hasBleFeature = false;
TextView tvMessage;
int messageId = R.string.doesnt_support_ble;
int colorId = android.R.color.holo_red_light;
private boolean mScanning;
private Handler handler = new Handler();
private static final long SCAN_PERIOD = 10000;
private static final int REQUEST_ENABLE_BT = 1209;
ListView listView;
ArrayList<BluetoothDevice> listDevices;
BleDeviceAdapter bleDeviceAdapter;
TextView tvHumidity;
TextView tvTemperature;
TextView tvPressure;
boolean isConnected = false;
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.blog_ble);
initParameters();
initViews();
scanLeDevice(true);
}
#SuppressLint("NewApi")
void initParameters()
{
hasBleFeature = getPackageManager().hasSystemFeature(PackageManager.FEATURE_BLUETOOTH_LE);
Log.i(TAG, "hasBleFeature : " + hasBleFeature);
if (hasBleFeature)
{
messageId = R.string.supports_ble;
colorId = android.R.color.holo_blue_light;
} else
{
messageId = R.string.doesnt_support_ble;
colorId = android.R.color.holo_red_light;
}
bluetoothManager = (BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE);
bluetoothAdapter = bluetoothManager.getAdapter();// BluetoothAdapter.getDefaultAdapter();
if (bluetoothAdapter == null || !bluetoothAdapter.isEnabled())
{
Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
}
listDevices = new ArrayList<BluetoothDevice>();
bleDeviceAdapter = new BleDeviceAdapter(this, listDevices);
}
void initViews()
{
tvHumidity = (TextView) findViewById(R.id.blog_ble_tv_humidity);
tvTemperature = (TextView) findViewById(R.id.blog_ble_tv_temprature);
tvPressure = (TextView) findViewById(R.id.blog_ble_tv_pressure);
tvMessage = (TextView) findViewById(R.id.blog_ble_tv_message);
tvMessage.setText(getResources().getString(messageId));
tvMessage.setTextColor(getResources().getColor(colorId));
listView = (ListView) findViewById(R.id.blog_ble_list_view);
listView.setAdapter(bleDeviceAdapter);
listView.setOnItemClickListener(this);
}
#SuppressLint("NewApi")
void scanLeDevice(final boolean enable)
{
if (enable)
{
handler.postDelayed(new Runnable()
{
#SuppressLint("NewApi")
#Override
public void run()
{
mScanning = false;
bluetoothAdapter.stopLeScan(leScanCallback);
}
}, SCAN_PERIOD);
mScanning = false;
bluetoothAdapter.startLeScan(leScanCallback);
} else
{
mScanning = false;
bluetoothAdapter.stopLeScan(leScanCallback);
}
}
#SuppressLint("NewApi")
private BluetoothAdapter.LeScanCallback leScanCallback = new BluetoothAdapter.LeScanCallback()
{
#Override
public void onLeScan(final BluetoothDevice device, int rssi, byte[] scanRecord)
{
runOnUiThread(new Runnable()
{
#Override
public void run()
{
if (device != null)
{
bleDeviceAdapter.add(device);
bleDeviceAdapter.notifyDataSetChanged();
}
}
});
}
};
class BleDeviceAdapter extends ArrayAdapter<BluetoothDevice>
{
public BleDeviceAdapter(Context context, List<BluetoothDevice> objects)
{
super(context, R.layout.row_ble_device, R.id.row_ble_device_tv_name, objects);
}
#SuppressLint("NewApi")
#Override
public View getView(int position, View convertView, ViewGroup parent)
{
View row = super.getView(position, convertView, parent);
ViewHolder holder = (ViewHolder) row.getTag();
if (holder == null)
{
holder = new ViewHolder(row);
row.setTag(holder);
}
BluetoothDevice device = getDevice(position);
holder.tvName.setText("" + device.getName());
Log.i(TAG, "" + device.getName());
return row;
}
}
BluetoothDevice getDevice(int position)
{
return (BluetoothDevice) listView.getAdapter().getItem(position);
}
#SuppressLint("NewApi")
#Override
public void onItemClick(AdapterView<?> arg0, View arg1, int position, long arg3)
{
BluetoothDevice device = getDevice(position);
Toast.makeText(this, "" + device.getName(), Toast.LENGTH_SHORT).show();
BluetoothGatt connectGatt = device.connectGatt(this, false, mGattCallback);
}
/* Client Configuration Descriptor */
private static final UUID CONFIG_DESCRIPTOR = UUID.fromString("00002902-0000-1000-8000-00805f9b34fb");
private static final UUID KITCHEN_SCALE_SERVICE = UUID.fromString("0000780a-0000-1000-8000-00805f9b34fb");
private static final UUID KITCHEN_SCALE_FEATURE_CHAR = UUID.fromString("00008aa0-0000-1000-8000-00805f9b34fb");
private static final UUID KITCHEN_SCALE_MEASUREMENT_CHAR = UUID.fromString("00008aa1-0000-1000-8000-00805f9b34fb");
private static final UUID KITCHEN_SCALE_INTERMEDIATE_CHAR = UUID.fromString("00008aa2-0000-1000-8000-00805f9b34fb");
/*
* In this callback, we've created a bit of a state machine to enforce that
* only one characteristic be read or written at a time until all of our
* sensors are enabled and we are registered to get notifications.
*/
#SuppressLint("NewApi")
private BluetoothGattCallback mGattCallback = new BluetoothGattCallback()
{
/* State Machine Tracking */
private int mState = 0;
private void reset()
{
mState = 0;
}
private void advance()
{
mState++;
}
/*
* Send an enable command to each sensor by writing a configuration
* characteristic. This is specific to the SensorTag to keep power low
* by disabling sensors you aren't using.
*/
private void enableNextSensor(BluetoothGatt gatt)
{
BluetoothGattCharacteristic characteristic;
switch (mState)
{
case 0:
Log.i(TAG, "Enabling weight scale");
characteristic = gatt.getService(KITCHEN_SCALE_SERVICE).getCharacteristic(KITCHEN_SCALE_FEATURE_CHAR);
Log.i(TAG, "Feature Properties : "+characteristic.getProperties());
characteristic.setValue(new byte[]
{ 0x09 });
break;
default:
mHandler.sendEmptyMessage(MSG_DISMISS);
Log.i(TAG, "All Sensors Enabled");
return;
}
gatt.writeCharacteristic(characteristic);
}
/*
* Read the data characteristic's value for each sensor explicitly
*/
private void readNextSensor(BluetoothGatt gatt)
{
BluetoothGattCharacteristic characteristic;
switch (mState)
{
case 0:
Log.i(TAG, "Reading weight cal");
characteristic = gatt.getService(KITCHEN_SCALE_SERVICE).getCharacteristic(KITCHEN_SCALE_MEASUREMENT_CHAR);
break;
default:
mHandler.sendEmptyMessage(MSG_DISMISS);
Log.i(TAG, "All Sensors Enabled");
return;
}
gatt.readCharacteristic(characteristic);
}
/*
* Enable notification of changes on the data characteristic for each
* sensor by writing the ENABLE_NOTIFICATION_VALUE flag to that
* characteristic's configuration descriptor.
*/
private void setNotifyNextSensor(BluetoothGatt gatt)
{
BluetoothGattCharacteristic characteristic;
switch (mState)
{
case 0:
Log.i(TAG, "Set notify weight ");
characteristic = gatt.getService(KITCHEN_SCALE_SERVICE).getCharacteristic(KITCHEN_SCALE_MEASUREMENT_CHAR);
break;
default:
mHandler.sendEmptyMessage(MSG_DISMISS);
Log.i(TAG, "All Sensors Enabled");
return;
}
// Enable local notifications
gatt.setCharacteristicNotification(characteristic, true);
// Enabled remote notifications
BluetoothGattDescriptor desc = characteristic.getDescriptor(CONFIG_DESCRIPTOR);
desc.setValue(BluetoothGattDescriptor.ENABLE_NOTIFICATION_VALUE);
gatt.writeDescriptor(desc);
}
#Override
public void onConnectionStateChange(BluetoothGatt gatt, int status, int newState)
{
Log.i(TAG, "Connection State Change: " + status + " -> " + connectionState(newState));
if (status == BluetoothGatt.GATT_SUCCESS && newState == BluetoothProfile.STATE_CONNECTED)
{
/*
* Once successfully connected, we must next discover all the
* services on the device before we can read and write their
* characteristics.
*/
gatt.discoverServices();
mHandler.sendMessage(Message.obtain(null, MSG_PROGRESS, "Discovering Services..."));
} else if (status == BluetoothGatt.GATT_SUCCESS && newState == BluetoothProfile.STATE_DISCONNECTED)
{
/*
* If at any point we disconnect, send a message to clear the
* weather values out of the UI
*/
mHandler.sendEmptyMessage(MSG_CLEAR);
} else if (status != BluetoothGatt.GATT_SUCCESS)
{
/*
* If there is a failure at any stage, simply disconnect
*/
gatt.disconnect();
}
}
#Override
public void onServicesDiscovered(BluetoothGatt gatt, int status)
{
Log.i(TAG, "Services Discovered: " + status);
if (status == BluetoothGatt.GATT_SUCCESS)
{
Log.i(TAG, "No of services discovered: " + gatt.getServices().size());
mHandler.sendMessage(Message.obtain(null, MSG_PROGRESS, "No of services discovered: " + gatt.getServices().size()));
List<BluetoothGattService> services = gatt.getServices();
for (BluetoothGattService bluetoothGattService : services)
{
UUID uuid = bluetoothGattService.getUuid();
Log.e(TAG, ""+uuid.toString());
List<BluetoothGattCharacteristic> characteristics = bluetoothGattService.getCharacteristics();
for (BluetoothGattCharacteristic bluetoothGattCharacteristic : characteristics)
{
UUID uuidC = bluetoothGattCharacteristic.getUuid();
Log.i(TAG, "Gatt Properties : "+bluetoothGattCharacteristic.getProperties());
Log.i(TAG, ""+uuidC.toString());
CharacteristicHelper helper = new CharacteristicHelper(bluetoothGattCharacteristic);
Log.i(TAG, "isRead : "+helper.isRead());
Log.i(TAG, "isWrite : "+helper.isWrite());
Log.i(TAG, "isNotify : "+helper.isNotify());
Log.i(TAG, "isWriteNoResponse : "+helper.isWriteNoResponse());
}
}
}
// mHandler.sendMessage(Message.obtain(null, MSG_PROGRESS,
// "Enabling Sensors..."));
/*
* With services discovered, we are going to reset our state machine
* and start working through the sensors we need to enable
*/
reset();
enableNextSensor(gatt);
}
#Override
public void onCharacteristicRead(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic, int status)
{
Log.i(TAG, "onCharacteristicRead");
// For each read, pass the data up to the UI thread to update the
// display
/**methodToUpdateUI().*/
// After reading the initial value, next we enable notifications
setNotifyNextSensor(gatt);
}
#Override
public void onCharacteristicWrite(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic, int status)
{
Log.i(TAG, "onCharacteristicWrite");
// After writing the enable flag, next we read the initial value
readNextSensor(gatt);
}
#Override
public void onCharacteristicChanged(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic)
{
Log.i(TAG, "onCharacteristicChanged");
/*
* After notifications are enabled, all updates from the device on
* characteristic value changes will be posted here. Similar to
* read, we hand these up to the UI thread to update the display.
*/
}
#Override
public void onDescriptorWrite(BluetoothGatt gatt, BluetoothGattDescriptor descriptor, int status)
{
Log.i(TAG, "onDescriptorWrite");
// Once notifications are enabled, we move to the next sensor and
// start over with enable
advance();
enableNextSensor(gatt);
}
#Override
public void onReadRemoteRssi(BluetoothGatt gatt, int rssi, int status)
{
Log.i(TAG, "Remote RSSI: " + rssi);
}
private String connectionState(int status)
{
switch (status)
{
case BluetoothProfile.STATE_CONNECTED:
return "Connected";
case BluetoothProfile.STATE_DISCONNECTED:
return "Disconnected";
case BluetoothProfile.STATE_CONNECTING:
return "Connecting";
case BluetoothProfile.STATE_DISCONNECTING:
return "Disconnecting";
default:
return String.valueOf(status);
}
}
};
/*
* We have a Handler to process event results on the main thread
*/
private static final int MSG_PROGRESS = 201;
private static final int MSG_DISMISS = 202;
private static final int MSG_CLEAR = 301;
private Handler mHandler = new Handler()
{
#SuppressLint("NewApi")
#Override
public void handleMessage(Message msg)
{
BluetoothGattCharacteristic characteristic;
switch (msg.what)
{
case MSG_PROGRESS:
tvMessage.setText((String) msg.obj);
break;
case MSG_DISMISS:
tvMessage.setText("Service Enabled");
break;
case MSG_CLEAR:
tvMessage.setText("");
break;
}
}
};
}
In my activity, first of all I am scanning all the available devices & preparing ListView. On clicking on list item I connect to that particular device. When device's status become connected then I discover services. I have UUIDs of the device's service & its characteristics. But I am not sure how to write to any particular characteristics or enable or read data from it.
Although I have tried this thing but I don't see any success.
If any one has any idea about it, so please help me.
Had a device which required me to use
descriptor.setValue(BluetoothGattDescriptor.ENABLE_INDICATION_VALUE)
instead of
descriptor.setValue(BluetoothGattDescriptor.ENABLE_NOTIFICATION_VALUE)
as explained in this question
Android BLE API: GATT Notification not received
Refer the source code of sample application "bluetoothlegatt" provided on developer portal.
Sample service:
http://developer.android.com/samples/BluetoothLeGatt/src/com.example.android.bluetoothlegatt/BluetoothLeService.html
Using service:
http://developer.android.com/samples/BluetoothLeGatt/src/com.example.android.bluetoothlegatt/DeviceControlActivity.html
This example contains characteristics with read and notify properties. So you definitely find your solution. Please go to section with following code:(You may figure it out)
public void readCharacteristic(BluetoothGattCharacteristic characteristic) {
if (mBluetoothAdapter == null || mBluetoothGatt == null) {
Log.w(TAG, "BluetoothAdapter not initialized");
return;
}
mBluetoothGatt.readCharacteristic(characteristic);
}
you have to differentiate the value is notification or indication, and set respective value using descriptor.setValue. if you set wrongly, you will not get the value.
This one is working for me:
to notify master device that some characteristic is change, call this function on your pheripheral:
private BluetoothGattServer server;
//init....
//on BluetoothGattServerCallback...
//call this after change the characteristic
server.notifyCharacteristicChanged(device, characteristic, false);
in your master device: enable setCharacteristicNotification after discover the service:
#Override
public void onServicesDiscovered(BluetoothGatt gatt, int status) {
super.onServicesDiscovered(gatt, status);
services = mGatt.getServices();
for(BluetoothGattService service : services){
if( service.getUuid().equals(SERVICE_UUID)) {
characteristicData = service.getCharacteristic(CHAR_UUID);
for (BluetoothGattDescriptor descriptor : characteristicData.getDescriptors()) {
descriptor.setValue( BluetoothGattDescriptor.ENABLE_INDICATION_VALUE);
mGatt.writeDescriptor(descriptor);
}
gatt.setCharacteristicNotification(characteristicData, true);
}
}
if (dialog.isShowing()){
mHandler.post(new Runnable() {
#Override
public void run() {
dialog.hide();
}
});
}
}
now you can check your characteristic value is change, for example onCharacteristicRead function :
#Override
public void onCharacteristicRead(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic, int status) {
Log.i("onCharacteristicRead", characteristic.toString());
byte[] value=characteristic.getValue();
String v = new String(value);
Log.i("onCharacteristicRead", "Value: " + v);
}

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