How to read characteristic from BLE device until it have results?

How to read characteristic from BLE device until it have results? - android

I'm building an app that should to connect with a BLE device.
This device, storage the information that retreive from its sensors in a queque.
It is possibile that at the time X, the queque of this device have 100 items value.
Now my Android application must to connect of it, and download the data of the characteristic untile the queque of devis is empty.
This is the code that I use to read one value at time. How can I change it to get all data ?
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_ble);
mHandler = new Handler();
//mSensors = db.getAllSensorTypes();
//BLUETOOTH LOW ENERGY NON SUPPORTATO
if (!getPackageManager().hasSystemFeature(PackageManager.FEATURE_BLUETOOTH_LE)) {
Toast.makeText(this, "BLE Not Supported",
Toast.LENGTH_SHORT).show();
finish();
}
final BluetoothManager bluetoothManager =
(BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE);
mBluetoothAdapter = bluetoothManager.getAdapter();
//VERIFICO SE IL BLUETOOTH DEL DISPOSITIVO E' ABILITATO
//OPPURE NO. SE NON è ABILITATO DEVO CHIEDERE ALL'UTENTE DI ATTIVARLO
// Ensures Bluetooth is available on the device and it is enabled. If not,
if (mBluetoothAdapter == null || !mBluetoothAdapter.isEnabled()) {
Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
}
tvBLE = (TextView) findViewById(R.id.tvBLE);
ibDownload = (ImageButton) findViewById(R.id.ibDownload);
//ibDownload.setEnabled(false);
ibDownload.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
if(currDevice!=null){
GattClientCallback gattClientCallback = new GattClientCallback();
mGatt = currDevice.connectGatt(getBaseContext(), false, gattClientCallback);
scanLeDevice(false);// will stop after first device detection
}
refreshListView();
}
});
// Bluetooth is supported?
if (mBluetoothAdapter == null) {
Toast.makeText(this, "Bluetooth non supportato", Toast.LENGTH_SHORT).show();
finish();
}
}
private void scanLeDevice(final boolean enable) {
if (enable) {
mHandler.postDelayed(new Runnable() {
#Override
public void run() {
if (Build.VERSION.SDK_INT < 21) {
mBluetoothAdapter.stopLeScan(mLeScanCallback);
} else {
mLEScanner.stopScan(mScanCallback);
}
}
}, SCAN_PERIOD);
if (Build.VERSION.SDK_INT < 21) {
mBluetoothAdapter.startLeScan(mLeScanCallback);
} else {
mLEScanner.startScan(filters, settings, mScanCallback);
}
} else {
if (Build.VERSION.SDK_INT < 21) {
mBluetoothAdapter.stopLeScan(mLeScanCallback);
} else {
mLEScanner.stopScan(mScanCallback);
}
}
}
private ScanCallback mScanCallback = new ScanCallback() {
#Override
public void onScanResult(int callbackType, ScanResult result) {
Log.i("callbackType", String.valueOf(callbackType));
Log.i("result", result.toString());
BluetoothDevice btDevice = result.getDevice();
connectToDevice(btDevice);
}
#Override
public void onBatchScanResults(List<ScanResult> results) {
for (ScanResult sr : results) {
Log.i("ScanResult - Results", sr.toString());
}
}
#Override
public void onScanFailed(int errorCode) {
Log.e("Scan Failed", "Error Code: " + errorCode);
}
};
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("onLeScan", device.toString());
connectToDevice(device);
}
});
}
};
public void connectToDevice(BluetoothDevice device) {
String nomeDispositivo = device.getName();
if (mGatt == null && device.getName()!= null && device.getName().equals("Diabesity care")) {
currDevice = device;
ibDownload.setEnabled(true);
ibDownload.setImageResource(R.drawable.download_ok);
//mGatt = device.connectGatt(this, false, gattCallback);
//scanLeDevice(false);// will stop after first device detection
}
}
private class GattClientCallback extends BluetoothGattCallback {
#Override
public void onConnectionStateChange(BluetoothGatt gatt, int status, int newState) {
super.onConnectionStateChange(gatt, status, newState);
Log.i("tag","onConnectionStateChange newState: " + newState);
if (status == BluetoothGatt.GATT_FAILURE) {
logError("Connection Gatt failure status " + status);
disconnectGattServer();
return;
} else if (status != BluetoothGatt.GATT_SUCCESS) {
// handle anything not SUCCESS as failure
logError("Connection not GATT sucess status " + status);
disconnectGattServer();
return;
}
if (newState == BluetoothProfile.STATE_CONNECTED) {
Log.i("INFO","Connected to device " + gatt.getDevice().getAddress());
setConnected(true);
gatt.discoverServices();
} else if (newState == BluetoothProfile.STATE_DISCONNECTED) {
Log.i("INFO","Disconnected from device");
disconnectGattServer();
}
}
#Override
public void onServicesDiscovered(BluetoothGatt gatt, int status) {
super.onServicesDiscovered(gatt, status);
if (status != BluetoothGatt.GATT_SUCCESS) {
Log.i("INFO","Device service discovery unsuccessful, status " + status);
return;
}
List<BluetoothGattCharacteristic> matchingCharacteristics = BluetoothUtils.findCharacteristics(gatt);
if (matchingCharacteristics.isEmpty()) {
logError("Unable to find characteristics.");
return;
}
ReadQueue = new ArrayList<>();
for (BluetoothGattCharacteristic characterist: matchingCharacteristics) {
ReadQueue.add(characterist);
}
ReadQueueIndex = 1;
ReadCharacteristics(ReadQueueIndex);
}
private void ReadCharacteristics(int index){
mGatt.readCharacteristic(ReadQueue.get(index));
}
#Override
public void onCharacteristicRead(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic, int status) {
super.onCharacteristicRead(gatt, characteristic, status);
if (status == BluetoothGatt.GATT_SUCCESS) {
Log.i("INFO","Characteristic read successfully");
//readCharacteristic(characteristic);
SensorData mSenData = new SensorData();
mSenData.setValue(characteristic.getStringValue(0));
//TO-DO HO COMMENTATO QUESTA RIGA DI CODICE
// mSenData.setIdType(st.getId());
mSenData.setIdType(++id);
mSenData.setCharacteristic(characteristic.getUuid().toString());
mSenData.setValueTimestamp(db.getDateTime());
//inserisco i dati nel db
db.insertSensorData(mSenData);
ReadQueue.remove(ReadQueue.get(ReadQueueIndex));
if (ReadQueue.size() >= 0) {
ReadQueueIndex--;
if (ReadQueueIndex == -1) {
Log.i("Read Queue: ", "Complete");
}
else {
ReadCharacteristics(ReadQueueIndex);
}
}
//refreshListView();
} else {
logError("Characteristic read unsuccessful, status: " + status);
// Trying to read from the Time Characteristic? It doesnt have the property or permissions
// set to allow this. Normally this would be an error and you would want to:
// disconnectGattServer();
}
}
}
}

Related

How to increase readCharacteristic of Ble device?

I'm building an app that downlaod all characteristic from a BLE device. This device storage in your local memory 10 distinct double values, every 3ms.
So in 1 second the BLE device has storage 333 row (every row have 10 values).
My Android app, download this values but I can to downlaod one rows of second or little less. In this mode I can't never to download all the information of this BLE device.
Now there is any way to increase the frequency of scan o read this characteristic ?
this is my Service that downlaod the characteristic of BLE device:
public class BlePowerService extends Service {
public DbLayer db;
Setting settingApp;
List<ScanFilter> filters;
String[] stringSequence = new String[] {CHARACTERISTIC_FORZA_STRING, CHARACTERISTIC_TEMPERATURA_STRING};
BluetoothAdapter mBluetoothAdapter;
BluetoothGatt mGatt;
BluetoothDevice currDevice;
static final long SCAN_PERIOD = 500;
static String SPLIT_CHAR =";";
BluetoothLeScanner mLEScanner;
Handler mHandler;
int ReadQueueIndex;
List<BluetoothGattCharacteristic> ReadQueue;
BluetoothGattCharacteristic caratteristicaDaLeggere;
ScanSettings settings;
Integer ultimaForzaLetta,ultimaTemperaturaLetta;
boolean continuaLetturaForza, continuaLetturaTemperatura;
boolean isReading = true;
String LOG_CODE = "NOTIFSRV";
GattClientCallback gattClientCallback;
private static final int PERMISSION_REQUEST_COARSE_LOCATION = 1;
public BlePowerService() {
}
#Override
public void onCreate() {
super.onCreate();
mHandler = new Handler();
Context sharedContext = null;
try {
sharedContext = this.createPackageContext(
"com.care.devicesensor",
Context.CONTEXT_INCLUDE_CODE);
if (sharedContext == null) {
return;
}
db=new DbLayer(sharedContext);
db.open();
} catch (Exception e) {
String error = e.getMessage();
// Log.d(LOG_CODE,"DB error : " + error);
return;
}
}
#Override
public int onStartCommand(Intent intent, int flags, int startId) {
try {
//RECUPERO LE IMPOSTAZIONI SETTATE DALL'UTENTE
settingApp = db.fetchSetting();
if (settingApp != null && settingApp.getAddressBleSX()!=null) {
//POSSO FILTRARE DIRETTAMENTE PER L'UUID DEL DISPOSITIVO MEMORIZZATO
//DALL'UTENTE
ScanFilter.Builder scanFilterMac =
null;
scanFilterMac = new ScanFilter.Builder().setDeviceAddress(settingApp.getAddressBleSX());
if(filters==null)
filters = new ArrayList<ScanFilter>();
//if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
filters.add(scanFilterMac.build());
//}
//FILTRO ANCHE PER LA CARATTERISTICA DI FORZA
ScanFilter filter = null;
filter = new ScanFilter.Builder().setServiceUuid(ParcelUuid.fromString(CHARACTERISTIC_FORZA_STRING)).build();
filters.add(filter);
final BluetoothManager bluetoothManager =
(BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE);
mBluetoothAdapter = bluetoothManager.getAdapter();
//mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
mLEScanner = mBluetoothAdapter.getBluetoothLeScanner();
settings = new ScanSettings.Builder()
.setScanMode(ScanSettings.SCAN_MODE_LOW_POWER)
.build();
scanLeDevice(true);
mTimer = new Timer();
//ogni 2 ore
continuaLetturaForza = true;
continuaLetturaTemperatura = true;
int nSecondi = settingApp.getFrequenzaDownload()!= null ? settingApp.getFrequenzaDownload() : 1;
mTimer.schedule(timerTask,5000);
//mTimer.schedule(timerTask, 10000, 1000 * nSecondi);
//mTimer.scheduleAtFixedRate (timerTask, 10000, 1000 * nSecondi);
}
} catch (Exception e) {
// Log.e("POWER_SERVICE", e.getMessage());
}
return super.onStartCommand(intent, flags, startId);
}
private Timer mTimer;
TimerTask timerTask = new TimerTask() {
#RequiresApi(api = Build.VERSION_CODES.JELLY_BEAN_MR2)
#Override
public void run() {
//LEGGO TUTTI I DATI DAL SENSORE FINCHE CI SONO VALORI
int counter = 0;
while(continuaLetturaForza || continuaLetturaTemperatura){
counter++;
//Log.v("CICLO WHILE", counter+"");
if (currDevice != null) {
if(ReadQueue!= null && ReadQueue.size()>0){
int index =0;
for(index=0; index < ReadQueue.size(); index++){
if(mGatt!=null){
isReading = mGatt.readCharacteristic(ReadQueue.get(index));
while(isReading){
try {
Thread.sleep(1);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}else{
continuaLetturaForza = false;
continuaLetturaTemperatura = false;
}
}
}
}else{
//provo a ricollegarmi al dispositivo probabile, abbia perso la connessione con esso
scanLeDevice(true);
try {
Thread.sleep(2500);
} catch (InterruptedException e) {
e.printStackTrace();
}
if(currDevice == null && counter == 25){
//in questo caso non è riuscito a trovare il dispositivo BLE
//esco dal ciclo
continuaLetturaForza = false;
continuaLetturaTemperatura = false;
continue;
}
}
}
if(gattClientCallback!=null && mGatt != null)
gattClientCallback.disconnectGattServer();
mTimer.cancel();
stopSelf();
EventBus.getDefault().post(new MessageEvent("stopService"));
}
public void stopTask() {
if (timerTask != null) {
Log.d("TIMER", "timer canceled");
timerTask.cancel();
}
}
};
public void connectToDevice(BluetoothDevice device) {
//VERIFICO SE IL DEVICE è QUELLO CHE VOGLIO IO
if (mGatt == null && settingApp != null
&& device.getAddress().equals(settingApp.getAddressBleSX())) {
currDevice = device;
gattClientCallback = new GattClientCallback();
mGatt = currDevice.connectGatt(getBaseContext(), false, gattClientCallback);
scanLeDevice(false);// will stop after first device detection
}
}
private BluetoothAdapter.LeScanCallback mLeScanCallback =
new BluetoothAdapter.LeScanCallback() {
#Override
public void onLeScan(final BluetoothDevice device, int rssi,
byte[] scanRecord) {
Handler h = new Handler(getApplicationContext().getMainLooper());
// Although you need to pass an appropriate context
h.post(new Runnable() {
#Override
public void run() {
// Log.i("onLeScan", device.toString());
connectToDevice(device);
}
});
}
};
private void scanLeDevice(final boolean enable) {
if (enable) {
mHandler.postDelayed(new Runnable() {
#Override
public void run() {
if (Build.VERSION.SDK_INT < 21) {
mBluetoothAdapter.stopLeScan(mLeScanCallback);
} else {
mLEScanner.stopScan(mScanCallback);
}
}
}, SCAN_PERIOD);
if (Build.VERSION.SDK_INT < 21) {
mBluetoothAdapter.startLeScan(mLeScanCallback);
} else {
mLEScanner.startScan(filters, settings, mScanCallback);
}
} else {
if (Build.VERSION.SDK_INT < 21) {
mBluetoothAdapter.stopLeScan(mLeScanCallback);
} else {
mLEScanner.stopScan(mScanCallback);
}
}
}
private ScanCallback mScanCallback = new ScanCallback() {
#Override
public void onScanResult(int callbackType, ScanResult result) {
// Log.i("callbackType", String.valueOf(callbackType));
// Log.i("result", result.toString());
BluetoothDevice btDevice = null;
btDevice = result.getDevice();
connectToDevice(btDevice);
}
#Override
public void onBatchScanResults(List<ScanResult> results) {
for (ScanResult sr : results) {
Log.i("ScanResult - Results", sr.toString());
}
}
#Override
public void onScanFailed(int errorCode) {
Log.e("Scan Failed", "Error Code: " + errorCode);
}
};
private class GattClientCallback extends BluetoothGattCallback {
#Override
public void onConnectionStateChange(BluetoothGatt gatt, int status, int newState) {
try{
super.onConnectionStateChange(gatt, status, newState);
//Log.i("tag", "onConnectionStateChange newState: " + newState);
if (status == BluetoothGatt.GATT_FAILURE) {
Log.e("ERROR_SERVICE", "Connection Gatt failure status " + status);
if(mGatt == null){
}else{
try {
gatt.close();
} catch (Exception e) {
Log.d("", "close ignoring: " + e);
}
mGatt = null;
}
return;
} else if (status != BluetoothGatt.GATT_SUCCESS) {
// handle anything not SUCCESS as failure
Log.e("ERROR_SERVICE", "Connection not GATT sucess status " + status);
if(mGatt == null){
}else{
try {
gatt.close();
} catch (Exception e) {
Log.d("", "close ignoring: " + e);
}
mGatt = null;
}
return;
}
if (newState == BluetoothProfile.STATE_CONNECTED) {
//Log.i("INFO", "Connected to device " + gatt.getDevice().getAddress());
gatt.discoverServices();
} else if (newState == BluetoothProfile.STATE_DISCONNECTED) {
Log.i("INFO", "Disconnected from device");
if(mGatt == null){
}else{
try {
mGatt.close();
mGatt = null;
currDevice = null;
} catch (Exception e) {
Log.d("", "close ignoring: " + e);
}
mGatt = null;
}
}
}catch(Exception e){
Log.e("tag", e.getMessage());
continuaLetturaForza = true;
continuaLetturaTemperatura = true;
}
}
public void disconnectGattServer() {
continuaLetturaForza = true;
continuaLetturaTemperatura = true;
isReading = false;
if (mGatt == null) {
}
else{
try{
mGatt.disconnect();
// mGatt.close();
}catch(Exception e){
mGatt = null;
}
}
//mGatt = null;
//currDevice = null;
}
#Override
public void onServicesDiscovered(BluetoothGatt gatt, int status) {
super.onServicesDiscovered(gatt, status);
if (status != BluetoothGatt.GATT_SUCCESS) {
// Log.i("INFO", "Device service discovery unsuccessful, status " + status);
return;
}
List<BluetoothGattCharacteristic> matchingCharacteristics =
BluetoothUtils.findCharacteristics(gatt,stringSequence);
if (matchingCharacteristics.isEmpty()) {
// Log.e("ERROR_SERVICE","Unable to find characteristics.");
return;
}else {
ReadQueue = new ArrayList<>();
for (BluetoothGattCharacteristic characterist : matchingCharacteristics) {
ReadQueue.add(characterist);
}
//ReadQueueIndex = 0;
//ReadCharacteristics(ReadQueueIndex);
}
}
#Override
public void onCharacteristicRead(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic, int status) {
super.onCharacteristicRead(gatt, characteristic, status);
if (status == BluetoothGatt.GATT_SUCCESS) {
String valoreRestituito = characteristic.getStringValue(0);
if(valoreRestituito==null){
int i = 0;
i = i + 1;
return;
}
//SPLITTO PER IL CARATTERE ;
String[] arrayValori = valoreRestituito.split(SPLIT_CHAR);
//1 valore è l ID
try{
int id = new Integer(arrayValori[0]);
//VERIFICO SE STO LEGGENDO TEMPERATURA O FORZA
if(characteristic.getUuid().equals(CHARACTERISTIC_FORZA_UUID)){
/*Log.v("CARATTERISTICA", "*****************************************");
Log.v("FORZA", "*****************************************");*/
if(ultimaForzaLetta!= null && ultimaForzaLetta == id){
continuaLetturaForza = false;
isReading = false;
return;
}
ultimaForzaLetta = id;
}else if(characteristic.getUuid().equals( CHARACTERISTIC_TEMPERATURA_UUID)){
/*Log.v("CARATTERISTICA", "*****************************************");
Log.v("TEMPERATURA", "*****************************************");*/
if(ultimaTemperaturaLetta!= null && ultimaTemperaturaLetta == id){
continuaLetturaTemperatura = false;
isReading = false;
return;
}
ultimaTemperaturaLetta = id;
}
SensorData mSenData = new SensorData();
mSenData.setIdType(id);
mSenData.setValue1(arrayValori[1]);
mSenData.setValue2(arrayValori[2]);
mSenData.setValue3(arrayValori[3]);
mSenData.setValue4(arrayValori[4]);
mSenData.setValue5(arrayValori[5]);
mSenData.setValue6(arrayValori[6]);
mSenData.setValue7(arrayValori[7]);
mSenData.setValue8(arrayValori[8]);
//TO-DO HO COMMENTATO QUESTA RIGA DI CODICE
// mSenData.setIdType(st.getId());
mSenData.setCharacteristic(characteristic.getUuid().toString());
mSenData.setValueTimestamp(db.getDateTime(true));
db.insertSensorData(mSenData);
EventBus.getDefault().post(new MessageEvent("update"));
}catch (Exception e){
Log.e("ERROR", e.getMessage());
}
isReading = false;
} else {
isReading = false;
Log.e("ERROR_SERVICE", "Characteristic read unsuccessful, status: " + status);
disconnectGattServer();
return;
}
}
}
public void onDestroy() {
try {
db.close();
Log.d(LOG_CODE,"DB connection closed" );
mTimer.cancel();
timerTask.cancel();
} catch (Exception e) {
e.printStackTrace();
}
}
}
The service works correctly but is to slow.

You can't do more than one read request per connection interval. Since 3 ms is much less than the minimum allowed connection interval, what you're trying to do seems impossible. You will have to make your protocol more efficient, for example by letting the peripheral send a stream of notifications. This way you can achieve multiple peckets per connection event.

Android and BLE device

I'm building an app that should to connect a BLE device and download all the information that this device has storage in your flash memory.
So I'm building this code:
This is the Timer that I use to download ALL the information every X minutes:
TimerTask timerTask = new TimerTask() {
#RequiresApi(api = Build.VERSION_CODES.JELLY_BEAN_MR2)
#Override
public void run() {
valore = true;
int conta = 0;
while(valore){
conta++;
if (currDevice != null) {
mGatt = currDevice.connectGatt(getBaseContext(), false, gattClientCallback);
}else{
//provo a ricollegarmi al dispositivo probabile, abbia perso la connessione con esso
scanLeDevice(true);
}
try {
Thread.sleep(300);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
};
This is the method that I use to connect at BLE device:
#RequiresApi(api = Build.VERSION_CODES.JELLY_BEAN_MR2)
public void connectToDevice(BluetoothDevice device) {
//VERIFICO SE IL DEVICE è QUELLO CHE VOGLIO IO
if (mGatt == null && settingApp != null
&& device.getAddress().equals(settingApp.getAddressBleSX())) {
currDevice = device;
gattClientCallback = new GattClientCallback();
mGatt = currDevice.connectGatt(getBaseContext(), false, gattClientCallback);
scanLeDevice(false);// will stop after first device detection
}
}
This is the LeScanCallback():
private BluetoothAdapter.LeScanCallback mLeScanCallback =
new BluetoothAdapter.LeScanCallback() {
#Override
public void onLeScan(final BluetoothDevice device, int rssi,
byte[] scanRecord) {
Handler h = new Handler(getApplicationContext().getMainLooper());
// Although you need to pass an appropriate context
h.post(new Runnable() {
#Override
public void run() {
// Log.i("onLeScan", device.toString());
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR2) {
connectToDevice(device);
}
}
});
}
};
This the last code to effectively download data from BLE device and storage it on SqlLite
private BluetoothAdapter.LeScanCallback mLeScanCallback =
new BluetoothAdapter.LeScanCallback() {
#Override
public void onLeScan(final BluetoothDevice device, int rssi,
byte[] scanRecord) {
Handler h = new Handler(getApplicationContext().getMainLooper());
// Although you need to pass an appropriate context
h.post(new Runnable() {
#Override
public void run() {
// Log.i("onLeScan", device.toString());
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR2) {
connectToDevice(device);
}
}
});
}
};
#RequiresApi(api = Build.VERSION_CODES.JELLY_BEAN_MR2)
private void scanLeDevice(final boolean enable) {
if (enable) {
mHandler.postDelayed(new Runnable() {
#Override
public void run() {
if (Build.VERSION.SDK_INT < 21) {
mBluetoothAdapter.stopLeScan(mLeScanCallback);
} else {
mLEScanner.stopScan(mScanCallback);
}
}
}, SCAN_PERIOD);
if (Build.VERSION.SDK_INT < 21) {
mBluetoothAdapter.startLeScan(mLeScanCallback);
} else {
mLEScanner.startScan(filters, settings, mScanCallback);
}
} else {
if (Build.VERSION.SDK_INT < 21) {
mBluetoothAdapter.stopLeScan(mLeScanCallback);
} else {
mLEScanner.stopScan(mScanCallback);
}
}
}
private ScanCallback mScanCallback = new ScanCallback() {
#RequiresApi(api = Build.VERSION_CODES.JELLY_BEAN_MR2)
#Override
public void onScanResult(int callbackType, ScanResult result) {
// Log.i("callbackType", String.valueOf(callbackType));
// Log.i("result", result.toString());
BluetoothDevice btDevice = null;
if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.LOLLIPOP) {
btDevice = result.getDevice();
}
connectToDevice(btDevice);
}
#Override
public void onBatchScanResults(List<ScanResult> results) {
for (ScanResult sr : results) {
// Log.i("ScanResult - Results", sr.toString());
}
}
#Override
public void onScanFailed(int errorCode) {
// Log.e("Scan Failed", "Error Code: " + errorCode);
}
};
#RequiresApi(api = Build.VERSION_CODES.JELLY_BEAN_MR2)
private class GattClientCallback extends BluetoothGattCallback {
#SuppressLint("LongLogTag")
#Override
public void onConnectionStateChange(BluetoothGatt gatt, int status, int newState) {
try{
super.onConnectionStateChange(gatt, status, newState);
Log.i("tag", "onConnectionStateChange newState: " + newState);
if (status == BluetoothGatt.GATT_FAILURE) {
Log.e("ERROR_SERVICE", "Connection Gatt failure status " + status);
disconnectGattServer();
return;
} else if (status != BluetoothGatt.GATT_SUCCESS) {
// handle anything not SUCCESS as failure
Log.e("ERROR_SERVICE", "Connection not GATT sucess status " + status);
disconnectGattServer();
return;
}
if (newState == BluetoothProfile.STATE_CONNECTED) {
//Log.i("INFO", "Connected to device " + gatt.getDevice().getAddress());
gatt.discoverServices();
} else if (newState == BluetoothProfile.STATE_DISCONNECTED) {
Log.i("INFO", "Disconnected from device");
disconnectGattServer();
}
}catch(Exception e){
Log.e("ON_CONNECTION_STATE_CHANGE", e.getMessage());
}
}
public void disconnectGattServer() {
valore = false;
if (mGatt != null) {
mGatt.disconnect();
mGatt.close();
}
}
#Override
public void onServicesDiscovered(BluetoothGatt gatt, int status) {
super.onServicesDiscovered(gatt, status);
if (status != BluetoothGatt.GATT_SUCCESS) {
// Log.i("INFO", "Device service discovery unsuccessful, status " + status);
return;
}
List<BluetoothGattCharacteristic> matchingCharacteristics =
BluetoothUtils.findCharacteristics(gatt,stringSequence);
if (matchingCharacteristics.isEmpty()) {
// Log.e("ERROR_SERVICE","Unable to find characteristics.");
return;
}else{
gatt.readCharacteristic(matchingCharacteristics.get(0));
}
}
#Override
public void onCharacteristicRead(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic, int status) {
super.onCharacteristicRead(gatt, characteristic, status);
if (status == BluetoothGatt.GATT_SUCCESS) {
SensorData mSenData = new SensorData();
mSenData.setValue(characteristic.getStringValue(0));
mSenData.setIdType(++id);
mSenData.setCharacteristic(characteristic.getUuid().toString());
mSenData.setValueTimestamp(db.getDateTime());
db.insertSensorData(mSenData);
} else {
Log.e("ERROR_SERVICE", "Characteristic read unsuccessful, status: " + status);
}
}
Now, if I try to start my application, I can download some data from BLE device as 35, 36 values. After that I received this message from onConnectionStateChange method
E/ERROR_SERVICE: Connection not GATT sucess status 128
So after this error, the timer stopped. After X minutes the method restart but I'm not able to download never error from BLE device.
So how can I download all data from BLE device every X minutes and until the BLE device have data storage in yuor memory ?

Bluetooth Low energy android app not working all the time

I have refereed the below link to create android app.
1)https://www.bignerdranch.com/blog/bluetooth-low-energy-part-1/
2)https://github.com/bignerdranch/android-bluetooth-testbed/tree/a/android-ble-part-1
But the app is not working all the time.

you can go through this sample code to get data from ble devices
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mHandler = new Handler();
if (!getPackageManager().hasSystemFeature(PackageManager.FEATURE_BLUETOOTH_LE)) {
Toast.makeText(this, "BLE Not Supported",
Toast.LENGTH_SHORT).show();
finish();
}
final BluetoothManager bluetoothManager =
(BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE);
mBluetoothAdapter = bluetoothManager.getAdapter();
}
#Override
protected void onResume() {
super.onResume();
if (mBluetoothAdapter == null || !mBluetoothAdapter.isEnabled()) {
Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
} else {
if (Build.VERSION.SDK_INT >= 21) {
mLEScanner = mBluetoothAdapter.getBluetoothLeScanner();
settings = new ScanSettings.Builder()
.setScanMode(ScanSettings.SCAN_MODE_LOW_LATENCY)
.build();
filters = new ArrayList<ScanFilter>();
}
scanLeDevice(true);
}
}
#Override
protected void onPause() {
super.onPause();
if (mBluetoothAdapter != null && mBluetoothAdapter.isEnabled()) {
scanLeDevice(false);
}
}
#Override
protected void onDestroy() {
if (mGatt == null) {
return;
}
mGatt.close();
mGatt = null;
super.onDestroy();
}
#Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
if (requestCode == REQUEST_ENABLE_BT) {
if (resultCode == Activity.RESULT_CANCELED) {
//Bluetooth not enabled.
finish();
return;
}
}
super.onActivityResult(requestCode, resultCode, data);
}
private void scanLeDevice(final boolean enable) {
if (enable) {
mHandler.postDelayed(new Runnable() {
#Override
public void run() {
if (Build.VERSION.SDK_INT < 21) {
mBluetoothAdapter.stopLeScan(mLeScanCallback);
} else {
mLEScanner.stopScan(mScanCallback);
}
}
}, SCAN_PERIOD);
if (Build.VERSION.SDK_INT < 21) {
mBluetoothAdapter.startLeScan(mLeScanCallback);
} else {
mLEScanner.startScan(filters, settings, mScanCallback);
}
} else {
if (Build.VERSION.SDK_INT < 21) {
mBluetoothAdapter.stopLeScan(mLeScanCallback);
} else {
mLEScanner.stopScan(mScanCallback);
}
}
}
private ScanCallback mScanCallback = new ScanCallback() {
#Override
public void onScanResult(int callbackType, ScanResult result) {
Log.e("callbackType", String.valueOf(callbackType));
Log.e("result", result.toString());//here you will get the details in ascii format and you have to convert that ascii to actual value
BluetoothDevice btDevice = result.getDevice();
connectToDevice(btDevice);
}
#Override
public void onBatchScanResults(List<ScanResult> results) {
for (ScanResult sr : results) {
Log.e("ScanResult - Results", sr.toString());
}
}
#Override
public void onScanFailed(int errorCode) {
Log.e("Scan Failed", "Error Code: " + errorCode);
}
};
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.e("onLeScan", device.toString());
connectToDevice(device);
}
});
}
};
public void connectToDevice(BluetoothDevice device) {
if (mGatt == null) {
mGatt = device.connectGatt(this, false, 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.e("onConnectionStateChange", "Status: " + status);
switch (newState) {
case BluetoothProfile.STATE_CONNECTED:
Log.e("gattCallback", "STATE_CONNECTED");
gatt.discoverServices();
break;
case BluetoothProfile.STATE_DISCONNECTED:
Log.e("gattCallback", "STATE_DISCONNECTED");
break;
default:
Log.e("gattCallback", "STATE_OTHER");
}
}
#Override
public void onServicesDiscovered(BluetoothGatt gatt, int status) {
List<BluetoothGattService> services = gatt.getServices();
Log.e("onServicesDiscovered", services.toString());
gatt.readCharacteristic(services.get(1).getCharacteristics().get
(0));
}
#Override
public void onCharacteristicRead(BluetoothGatt gatt,
BluetoothGattCharacteristic
characteristic, int status) {
Log.e("onCharacteristicRead", characteristic.toString());
gatt.disconnect();
}
};
and you have to add permission for bluetooth
<uses-permission android:name="android.permission.BLUETOOTH"/>
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN"/>
<usesfeature android:name="android.hardware.bluetooth_le"android:required="true"/>

Sending Data via Bluetooth LE from Arduino Mega to an Android App

I'm trying to send data via Bluetooth LE from my Arduino Mefa 2560 connected to a nRF8001 to my Android App. I already managed to find the Characteristics on Android sid, but I don't get notifications.
For the Arduino side I used a code snippet I found multiple times and changed it a bit, so it's counting up and sending every fifth number:
#include <SPI.h>
#include "Adafruit_BLE_UART.h"
#define ADAFRUITBLE_REQ 10
#define ADAFRUITBLE_RDY 2
#define ADAFRUITBLE_RST 9
Adafruit_BLE_UART BTLEserial = Adafruit_BLE_UART(ADAFRUITBLE_REQ, ADAFRUITBLE_RDY, ADAFRUITBLE_RST);
int value = 0;
void setup(void)
{
Serial.begin(9600);
while(!Serial);
BTLEserial.setDeviceName("MEGA1"); /* 7 characters max! */
BTLEserial.begin();
}
aci_evt_opcode_t laststatus = ACI_EVT_DISCONNECTED;
void loop()
{
BTLEserial.pollACI();
aci_evt_opcode_t status = BTLEserial.getState();
if (status != laststatus) {
if (status == ACI_EVT_DEVICE_STARTED) {
Serial.println(F("* Advertising started"));
}
if (status == ACI_EVT_CONNECTED) {
Serial.println(F("* Connected!"));
}
if (status == ACI_EVT_DISCONNECTED) {
Serial.println(F("* Disconnected or advertising timed out"));
}
laststatus = status;
}
if (status == ACI_EVT_CONNECTED) {
value = value+1;
String s = String(value);
uint8_t sendbuffer[20];
s.getBytes(sendbuffer, 20);
char sendbuffersize = min(20, s.length());
Serial.print(F("\n* Sending -> \"")); Serial.print((char *)sendbuffer); Serial.println("\"");
if (value %5 == 0) {
BTLEserial.write(sendbuffer, sendbuffersize);
Serial.println(F("* wrote"));
} else {
Serial.println(F("* filtered"));
}
delay(1000);
}
}
Also I have no problems, reading the expected numbers with an app like BluefruitLE.
For the Android side I used this Tutorial and also changed it a bit, so my code looks like this:
public class MainActivity extends Activity{
private static final String TAG = "MyBLEApplication";
private BluetoothAdapter mBluetoothAdapter;
private int REQUEST_ENABLE_BT = 1;
private Handler mHandler;
private static final long SCAN_PERIOD = 10000;
private BluetoothLeScanner mLEScanner;
private BluetoothGatt mGatt;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mHandler = new Handler();
if (!getPackageManager().hasSystemFeature(PackageManager.FEATURE_BLUETOOTH_LE)) {
Toast.makeText(this, "BLE Not Supported",
Toast.LENGTH_SHORT).show();
finish();
}
final BluetoothManager bluetoothManager =
(BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE);
mBluetoothAdapter = bluetoothManager.getAdapter();
}
#Override
protected void onResume() {
super.onResume();
if (mBluetoothAdapter == null || !mBluetoothAdapter.isEnabled()) {
Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
} else {
mLEScanner = mBluetoothAdapter.getBluetoothLeScanner();
scanLeDevice(true);
}
}
#Override
protected void onPause() {
super.onPause();
if (mBluetoothAdapter != null && mBluetoothAdapter.isEnabled()) {
scanLeDevice(false);
}
}
#Override
protected void onDestroy() {
if (mGatt == null) {
return;
}
mGatt.close();
mGatt = null;
super.onDestroy();
}
#Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
if (requestCode == REQUEST_ENABLE_BT) {
if (resultCode == Activity.RESULT_CANCELED) {
//Bluetooth not enabled.
finish();
return;
}
}
super.onActivityResult(requestCode, resultCode, data);
}
private void scanLeDevice(final boolean enable) {
if (enable) {
mHandler.postDelayed(new Runnable() {
#Override
public void run() {
mLEScanner.stopScan(mScanCallback);
}
}, SCAN_PERIOD);
mLEScanner.startScan(mScanCallback);
} else {
mLEScanner.stopScan(mScanCallback);
}
}
private ScanCallback mScanCallback = new ScanCallback() {
#Override
public void onScanResult(int callbackType, ScanResult result) {
Log.i(TAG, "callbackType: " + String.valueOf(callbackType));
Log.i(TAG, "result: " + result.toString());
BluetoothDevice btDevice = result.getDevice();
connectToDevice(btDevice);
}
#Override
public void onBatchScanResults(List<ScanResult> results) {
for (ScanResult sr : results) {
Log.i(TAG, "ScanResult - Results: " + sr.toString());
}
}
#Override
public void onScanFailed(int errorCode) {
Log.e(TAG, "San failed, Error Code: " + errorCode);
}
};
public void connectToDevice(BluetoothDevice device) {
if (mGatt == null && device.getName() != null && device.getName().equals("MEGA1")) {
mGatt = device.connectGatt(this, false, 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, "ConnectionState: " + status);
switch (newState) {
case BluetoothProfile.STATE_CONNECTED:
Log.i(TAG, "STATE_CONNECTED");
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 discovered: " + services.toString());
for (BluetoothGattService service : services){
if (service.getUuid().equals(UUID.fromString("6E400001-B5A3-F393-E0A9-E50E24DCCA9E"))){
for (BluetoothGattCharacteristic characteristic : service.getCharacteristics()){
if (characteristic.getUuid().equals(UUID.fromString("6E400003-B5A3-F393-E0A9-E50E24DCCA9E"))){
Log.i(TAG, "set notification for characteristic");
gatt.setCharacteristicNotification(characteristic, true);
}
}
}
}
}
#Override
public void onCharacteristicChanged(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic){
Log.i(TAG, "got notified");
}
};
}
My Problem now is, that I find the device, the UART Service and the Characteristic, but onCharacteristicChanged don't get called, so my Android Monitor looks like this:
I/MyBLEApplication: callbackType: 1
I/MyBLEApplication: result: ScanResult{mDevice=XX:XX:XX:XX:XX:XX, mScanRecord=ScanRecord [mAdvertiseFlags=6, mServiceUuids=[6e400001-b5a3-f393-e0a9-e50e24dcca9e], mManufacturerSpecificData={}, mServiceData={}, mTxPowerLevel=-2147483648, mDeviceName=MEGA1], mRssi=-26, mTimestampNanos=1262117579287571}
I/MyBLEApplication: callbackType: 1
I/MyBLEApplication: result: ScanResult{mDevice=XX:XX:XX:XX:XX:XX, mScanRecord=ScanRecord [mAdvertiseFlags=6, mServiceUuids=[6e400001-b5a3-f393-e0a9-e50e24dcca9e], mManufacturerSpecificData={}, mServiceData={}, mTxPowerLevel=-2147483648, mDeviceName=MEGA1], mRssi=-26, mTimestampNanos=1262117665316624}
I/MyBLEApplication: ConnectionState: 0
I/MyBLEApplication: STATE_CONNECTED
I/MyBLEApplication: Services discovered: [android.bluetooth.BluetoothGattService#340653e, android.bluetooth.BluetoothGattService#d382f9f, android.bluetooth.BluetoothGattService#3368e8ec, android.bluetooth.BluetoothGattService#2d2b44b5]
I/MyBLEApplication: set notification for characteristic
Also the serial monitor from the Arduino displays:
* Advertising started
* Connected!
* Sending -> "1"
* filtered
* Sending -> "2"
* filtered
* Sending -> "3"
* filtered
* Sending -> "4"
* filtered
* Sending -> "5"
So the program gets stuck after the first value it sends.
Any solutions, what I am doing wrong and how i can get it to work?

How to set buzzer for BLE device in Android

I'm developed Android app to manipulating with BLE device as shown in this
image.
The app can scan and connect the device, but I can't write correct characteristic to buzzer the tag. I write this code to do that:
private static final int ALERT_HIGH = 2;
private static final UUID IMMEDIATE_ALERT_UUID = UUID.fromString("00001802-0000-1000-8000-00805f9b34fb");
private static final UUID ALERT_LEVEL_UUID = UUID.fromString("00002a06-0000-1000-8000-00805f9b34fb");
public void ClickButton(View view)
{
BluetoothGattService alertService = mGatt.getService(IMMEDIATE_ALERT_UUID);
if (alertService == null)
{
Toast.makeText(this, "Immediate Alert service not found!", 1)
.show();
return;
}
BluetoothGattCharacteristic alertLevel = alertService.getCharacteristic(ALERT_LEVEL_UUID);
if (alertLevel == null)
{
Toast.makeText(this, "Alert Level charateristic not found!", 1)
.show();
return;
}
alertLevel.setValue(ALERT_HIGH, BluetoothGattCharacteristic.FORMAT_UINT8, 0);
mGatt.writeCharacteristic(alertLevel);
}
but no action happened!
I found this app iTracing on play store and it worked fine and it can buzzer the ble device.
I don't know where is the missing in my code; and don't know the problem in a previous function I used or in initialize of connection with this device!
Finally, this is the full code I used
public class MainActivity extends Activity {
private BluetoothAdapter mBluetoothAdapter;
private int REQUEST_ENABLE_BT = 1;
private Handler mHandler;
private static final long SCAN_PERIOD = 1000*60;
private BluetoothLeScanner mLEScanner;
private ScanSettings settings;
private List<ScanFilter> filters;
private BluetoothGatt mGatt;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mHandler = new Handler();
if (!getPackageManager().hasSystemFeature(PackageManager.FEATURE_BLUETOOTH_LE)) {
Toast.makeText(this, "BLE Not Supported",
Toast.LENGTH_SHORT).show();
finish();
}
final BluetoothManager bluetoothManager =
(BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE);
mBluetoothAdapter = bluetoothManager.getAdapter();
}
#Override
protected void onResume() {
super.onResume();
if (mBluetoothAdapter == null || !mBluetoothAdapter.isEnabled()) {
Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
} else {
if (Build.VERSION.SDK_INT >= 21) {
mLEScanner = mBluetoothAdapter.getBluetoothLeScanner();
settings = new ScanSettings.Builder()
.setScanMode(ScanSettings.SCAN_MODE_LOW_LATENCY)
.build();
filters = new ArrayList<ScanFilter>();
}
scanLeDevice(true);
}
}
#Override
protected void onPause() {
super.onPause();
if (mBluetoothAdapter != null && mBluetoothAdapter.isEnabled()) {
scanLeDevice(false);
}
}
#Override
protected void onDestroy() {
if (mGatt == null) {
return;
}
mGatt.close();
mGatt = null;
super.onDestroy();
}
#Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
if (requestCode == REQUEST_ENABLE_BT) {
if (resultCode == Activity.RESULT_CANCELED) {
//Bluetooth not enabled.
finish();
return;
}
}
super.onActivityResult(requestCode, resultCode, data);
}
private void scanLeDevice(final boolean enable) {
if (enable) {
mHandler.postDelayed(new Runnable() {
#Override
public void run() {
if (Build.VERSION.SDK_INT < 21) {
mBluetoothAdapter.stopLeScan(mLeScanCallback);
} else {
mLEScanner.stopScan(mScanCallback);
}
}
}, SCAN_PERIOD);
if (Build.VERSION.SDK_INT < 21) {
mBluetoothAdapter.startLeScan(mLeScanCallback);
} else {
mLEScanner.startScan(filters, settings, mScanCallback);
}
} else {
if (Build.VERSION.SDK_INT < 21) {
mBluetoothAdapter.stopLeScan(mLeScanCallback);
} else {
mLEScanner.stopScan(mScanCallback);
}
}
}
private ScanCallback mScanCallback = new ScanCallback() {
#Override
public void onScanResult(int callbackType, ScanResult result) {
Log.i("callbackType", String.valueOf(callbackType));
Log.i("result", result.toString());
BluetoothDevice btDevice = result.getDevice();
String DeviceAddress = btDevice.getAddress().trim();
if(DeviceAddress.equals("FF:FF:00:01:05:07"))
connectToDevice(btDevice);
}
#Override
public void onBatchScanResults(List<ScanResult> results) {
for (ScanResult sr : results) {
Log.i("ScanResult - Results", sr.toString());
}
}
#Override
public void onScanFailed(int errorCode) {
Log.e("Scan Failed", "Error Code: " + errorCode);
}
};
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("onLeScan", device.toString());
connectToDevice(device);
}
});
}
};
String address;
public void connectToDevice(BluetoothDevice device) {
if (mGatt == null) {
address = device.getAddress();
mGatt = device.connectGatt(this, false, gattCallback);
}
}
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:
Log.i("gattCallback", "STATE_CONNECTED");
mGatt.discoverServices();
break;
case BluetoothProfile.STATE_DISCONNECTED:
Log.e("gattCallback", "STATE_DISCONNECTED");
break;
default:
Log.e("gattCallback", "STATE_OTHER");
}
}
#Override
public void onServicesDiscovered(BluetoothGatt gatt, int status) {
List<BluetoothGattService> services = gatt.getServices();
Log.i("onServicesDiscovered", services.toString());
gatt.readCharacteristic(services.get(1).getCharacteristics().get
(0));
}
#Override
public void onCharacteristicRead(BluetoothGatt gatt,
BluetoothGattCharacteristic
characteristic, int status) {
Log.i("onCharacteristicRead", characteristic.toString());
gatt.disconnect();
}
};
private static final int ALERT_HIGH = 2;
private static final UUID IMMEDIATE_ALERT_UUID = UUID.fromString("00001802-0000-1000-8000-00805f9b34fb");
private static final UUID ALERT_LEVEL_UUID = UUID.fromString("00002a06-0000-1000-8000-00805f9b34fb");
public void ClickButton(View view)
{
BluetoothGattService alertService = mGatt.getService(IMMEDIATE_ALERT_UUID);
if (alertService == null)
{
Toast.makeText(this, "Immediate Alert service not found!", 1)
.show();
return;
}
BluetoothGattCharacteristic alertLevel = alertService.getCharacteristic(ALERT_LEVEL_UUID);
if (alertLevel == null)
{
Toast.makeText(this, "Alert Level charateristic not found!", 1)
.show();
return;
}
alertLevel.setValue(ALERT_HIGH, BluetoothGattCharacteristic.FORMAT_UINT8, 0);
mGatt.writeCharacteristic(alertLevel);
}
}
I will be grateful for help.

This is how I have done it in my code.
byte[] valToWrite = parseHexStringToBytes("0x0" + alertLevel);
immediateAlertChar.setValue(valToWrite);
boolean val = gatt.writeCharacteristic(immediateAlertChar);
Check also the response in onCharacteristicWrite() method

Develop Reference

The Android operating system is a mobile operating system that was developed by Google (GOOGL?) to be primarily used for touchscreen devices, cell phones, and tablets.

How to read characteristic from BLE device until it have results? - android

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