Develop Reference

BLE glucose meter

I am trying to get data from a glucose meter and I am not able to find good resources regarding the implementation on internet. Here is what I have been able to implement till now:
I am scanning the devices using BluetoothAdapter.LeScanCallback Interface:
#Override
public void onLeScan(BluetoothDevice device, int rssi, byte[] scanRecord) {
if ((device.getName() != null) && !bleDevices.contains(device)) {
bleDevices.add(device);
}
}
After getting the devices I am connecting to device using:
device.connectGatt(MainActivity.this, true, bleGattCallBack);
In BluetoothGattCallback class I am able to get the status connected in:
#Override
public void onConnectionStateChange(BluetoothGatt gatt, int status,
int newState) {
if (newState == BluetoothProfile.STATE_CONNECTED) {
connectionState = STATE_CONNECTED;
gatt.discoverServices();
} else if (newState == BluetoothProfile.STATE_DISCONNECTED) {
connectionState = STATE_DISCONNECTED;
gatt.close();
}
}
After that onServicesDiscovered gets called
#Override
public void onServicesDiscovered(BluetoothGatt gatt, int status) {
if (status == BluetoothGatt.GATT_SUCCESS) {
List<BluetoothGattService> gattServices = gatt.getServices();
for (BluetoothGattService gattService : gattServices) {
String serviceUUID = gattService.getUuid().toString();
if (serviceUUID.equals("00001808-0000-1000-8000-00805f9b34fb")) {
List<BluetoothGattCharacteristic> characteristics = gattService.getCharacteristics();
for (BluetoothGattCharacteristic characteristic : characteristics) {
if (characteristic.getUuid().equals(UUID.fromString("00002a18-0000-1000-8000-00805f9b34fb"))) {
BluetoothGattCharacteristic charGM =
gatt.getService(UUID.fromString("00001808-0000-1000-8000-00805f9b34fb"))
.getCharacteristic(UUID.fromString("00002a18-0000-1000-8000-00805f9b34fb"));
gatt.setCharacteristicNotification(charGM, true);
glucoseCharacteristic = characteristic;
BluetoothGattDescriptor descGM = charGM.getDescriptor(UUID.fromString(BleUuid.CHAR_CLIENT_CHARACTERISTIC_CONFIG_STRING));
descGM.setValue(BluetoothGattDescriptor.ENABLE_NOTIFICATION_VALUE);
gatt.writeDescriptor(descGM);
} else if (characteristic.getUuid().equals(UUID.fromString("00002a52-0000-1000-8000-00805f9b34fb"))) {
BluetoothGattCharacteristic charRACP =
gatt.getService(UUID.fromString("00001808-0000-1000-8000-00805f9b34fb"))
.getCharacteristic(UUID.fromString("00002a52-0000-1000-8000-00805f9b34fb"));
gatt.setCharacteristicNotification(charRACP, true);
BluetoothGattDescriptor descRACP = charRACP.getDescriptor(UUID.fromString(BleUuid.CHAR_CLIENT_CHARACTERISTIC_CONFIG_STRING));
descRACP.setValue(BluetoothGattDescriptor.ENABLE_INDICATION_VALUE);
gatt.writeDescriptor(descRACP);
}
}
}
} else {
}
}
After this onDescriptorWrite gets called:
#Override
public void onDescriptorWrite(BluetoothGatt gatt, BluetoothGattDescriptor descriptor, int status) {
super.onDescriptorWrite(gatt, descriptor, status);
if (status == BluetoothGatt.GATT_SUCCESS) {
Log.d(TAG, "onDescriptorWrite: GATT_SUCCESS");
BluetoothGattCharacteristic writeRACPchar =
gatt.getService(UUID.fromString("00001808-0000-1000-8000-00805f9b34fb"))
.getCharacteristic(UUID.fromString("00002a52-0000-1000-8000-00805f9b34fb"));
byte[] data = new byte[2];
data[0] = 0x01; // Report Stored records
data[1] = 0x01; // All records
writeRACPchar.setValue(data);
gatt.writeCharacteristic(writeRACPchar);
} else if (status == BluetoothGatt.GATT_INSUFFICIENT_AUTHENTICATION) {
if (gatt.getDevice().getBondState() != BluetoothDevice.BOND_NONE) {
Log.d(TAG, "onDescriptorWrite: GATT_INSUFFICIENT_AUTHENTICATION");
}
} else {
Log.d(TAG, "onDescriptorWrite: GATT_INSUFFICIENT_AUTHENTICATION");
}
}
and then onCharacteristicWrite
#Override
public void onCharacteristicWrite(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic, int status) {
super.onCharacteristicWrite(gatt, characteristic, status);
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));
Log.d(TAG, "onCharacteristicWrite: " + status + "\n" + characteristic.getUuid() + "\n" + stringBuilder.toString() + "\n" + characteristic.getValue().length);
}
}
Now, how do I proceed further? I know that I will get the data in onCharacteristicRead but that is never called.

Accessing to Heart Service in BLE device returns null

I'm trying to read the heart rate from a BLE device (It's a smartwatch and the model is CURREN R5 Pro), but when I get the Heart Rate Service, it returns null.
This is the code:
class Constants {
final static UUID HEART_RATE_SERVICE_UUID = convertFromInteger(0x180D);
final static UUID HEART_RATE_MEASUREMENT_UUID = convertFromInteger(0x2A37);
final static UUID HEART_RATE_CONTROL_POINT_UUID = convertFromInteger(0x2A39);
final static UUID CLIENT_CHARACTERISTIC_CONFIG_UUID = convertFromInteger(0x2902);
private static UUID convertFromInteger(int i) {
final long MSB = 0x0000000000001000L;
final long LSB = 0x800000805f9b34fbL;
long value = i & 0xFFFFFFFF;
return new UUID(MSB | (value << 32), LSB);
}
}
private final BluetoothGattCallback bluetoothGattCallback = new BluetoothGattCallback() {
#Override
public void onConnectionStateChange(BluetoothGatt gatt, int status, int newState) {
if (newState == BluetoothProfile.STATE_CONNECTED) {
bluetoothGatt.discoverServices();
Log.d(TAG, "Connected");
}
if (newState == BluetoothProfile.STATE_DISCONNECTED) {
Log.d(TAG, "Disconnected");
}
}
#Override
public void onServicesDiscovered(BluetoothGatt gatt, int status) {
if (status == BluetoothGatt.GATT_SUCCESS) {
//getCharacteristic(HEART_RATE_MEASUREMENT_UUID) returns null
BluetoothGattCharacteristic characteristic = gatt.getService(HEART_RATE_SERVICE_UUID)
.getCharacteristic(HEART_RATE_MEASUREMENT_UUID);
gatt.setCharacteristicNotification(characteristic, true);
BluetoothGattDescriptor descriptor = characteristic.getDescriptor(CLIENT_CHARACTERISTIC_CONFIG_UUID);
descriptor.setValue(BluetoothGattDescriptor.ENABLE_NOTIFICATION_VALUE);
gatt.writeDescriptor(descriptor);
}
}
#Override
public void onDescriptorWrite(BluetoothGatt gatt, BluetoothGattDescriptor descriptor, int status) {
BluetoothGattCharacteristic characteristic = gatt.getService(HEART_RATE_SERVICE_UUID)
.getCharacteristic(HEART_RATE_CONTROL_POINT_UUID);
characteristic.setValue(DATA_STREAMING_COMMAND);
gatt.writeCharacteristic(characteristic);
}
#Override
public void onCharacteristicChanged(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic) {
if (HEART_RATE_MEASUREMENT_UUID.equals(characteristic.getUuid())) {
Log.d(TAG, "HEART_RATE_MEASUREMENT_UUID");
//PROCESS DATA
}
if (HEART_RATE_CONTROL_POINT_UUID.equals(characteristic.getUuid())) {
Log.d(TAG, "HEART_RATE_CONTROL_POINT_UUID");
//PROCESS DATA
}
}
};
However, the only app that is able to read the heart rate from the device is Wearfit. Other applications are not able to read the heart rate from this device.
The services that I'm able to get are these:
00001800-0000-1000-8000-00805f9b34fb
00001801-0000-1000-8000-00805f9b34fb
6e400001-b5a3-f393-e0a9-e50e24dcca9e
00001530-1212-efde-1523-785feabcd123
0000fee7-0000-1000-8000-00805f9b34fb
Has anyone experienced this situation? Is there anything wrong with my code? Thanks for your help.

onCharacteristicChanged is not called after writing on ble

I need some response data from Ble. When I am writing something on ble I need to read response data from Ble. I am able to successfully enable and disable my ble device but only missing response data from ble. I also need to convert decimal time into Integer hex format like for 60 min into 0x3c.
private BluetoothGattCallback gattCallback= new BluetoothGattCallback() {
#RequiresApi(api = Build.VERSION_CODES.JELLY_BEAN_MR2)
#Override
public void onServicesDiscovered(BluetoothGatt gatt, int status) {
super.onServicesDiscovered(gatt,status);
clientGatt =gatt;
if (status == BluetoothGatt.GATT_SUCCESS) {
BluetoothGattService service = gatt.getServices().get(2);
List<BluetoothGattCharacteristic> gattCharacteristics = service.getCharacteristics();
for (BluetoothGattCharacteristic gattCharacteristic : gattCharacteristics) {
if (gattCharacteristic.getUuid().toString().equalsIgnoreCase(AppConstant.RECEIVE_UUID)) {
readCharacteristic=gattCharacteristic;
}
if (gattCharacteristic.getUuid().toString().equalsIgnoreCase(AppConstant.SEND_UUID_STR)) {
writeCharacteristic = gattCharacteristic;
}
}
}
}
#RequiresApi(api = Build.VERSION_CODES.JELLY_BEAN_MR2)
#Override
public void onCharacteristicRead(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic, int status) {
super.onCharacteristicRead(gatt,characteristic,status);
LogUtils.errorLog("onCharacteristicRead", "##: "+characteristic.getValue()[0]);
}
#RequiresApi(api = Build.VERSION_CODES.JELLY_BEAN_MR2)
#Override
public void onCharacteristicChanged(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic) {
super.onCharacteristicChanged(gatt, characteristic)
}
#RequiresApi(api = Build.VERSION_CODES.JELLY_BEAN_MR2)
#Override
public void onCharacteristicWrite(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic, int status) {
super.onCharacteristicWrite(gatt, characteristic, status);
setCharacteristicNotification(characteristic,true);
}
#TargetApi(Build.VERSION_CODES.JELLY_BEAN_MR2)
#Override
public void onConnectionStateChange(BluetoothGatt gatt, int status, int newState) {
super.onConnectionStateChange(gatt, status, newState);
clientGatt = gatt;
switch (newState) {
case BluetoothProfile.STATE_CONNECTED:
isBLE_Connected=true;
gatt.discoverServices();
break;
case BluetoothProfile.STATE_DISCONNECTED:
isBLE_Connected=false;
if(status==133 || status==22 || status==62){
refreshDeviceCache();
clientGatt.discoverServices();
}else{
clientGatt.disconnect();
clientGatt.close();
}
break;
}
}
};

Before onCharacteristicChanged is called you had to enable notification.
Someting like:
//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);
should help.

You when you write something on characteristic with the help of BluetoothGattDescriptor as
Mike's answer
You need to override the following method to listen to the changes has been completed then you can read the characteristics:
#Override
public void onDescriptorWrite(BluetoothGatt gatt, BluetoothGattDescriptor descriptor, int status) {
super.onDescriptorWrite(gatt, descriptor, status);
Log.d(TAG, "onDescriptorWrite :" + ((status == BluetoothGatt.GATT_SUCCESS) ? "Sucess" : "false"));
}

onCharacteristicChanged is not called in BluetoothGatt

What i am doing:
Connecting my Android app to the device using gatt.connect().
After connecting, i am discovering all the services.
Then, i am enabling the notification on all the control characteristics. It is a successful write.
After that, i am trying to write some data on one of those control characteristics, which is a success.
The expected behavior is that i should receive a reply on onCharacteristicChanged(), but it is not triggering.
Connecting:
mBluetoothGatt = device.connectGatt(mContext, false, mGattCallback);
mDevice = device;
GATT Callback
private final BluetoothGattCallback mGattCallback = new BluetoothGattCallback() {
#Override
public void onConnectionStateChange(BluetoothGatt gatt, int status, int newState) {
Log.i(Constant.BLUETOOTH_GATT_TAG, "Status: " + status);
super.onConnectionStateChange(gatt, status, newState);
switch (newState) {
case STATE_CONNECTED:
Log.i("gattCallback", "STATE_CONNECTED");
gatt.discoverServices();
break;
}
}
#Override
public void onServicesDiscovered(BluetoothGatt gatt, int status) {
super.onServicesDiscovered(gatt, status);
services = gatt.getServices();
for (BluetoothGattService service : services) {
Log.i("services Discovered", service.getUuid().toString());
}
BluetoothGattCharacteristic characteristic = gatt.getService(Constant.UUID_FRANK_SERVICE).getCharacteristic(Constant.UUID_ILLUMINATION_CONTROL_POINT_CHARACTERISTICS);
Log.d("Notification Enabled", "" + enableNotificationsForCharacteristic(characteristic));
//getAuthenticated();
}
#Override
public void onCharacteristicChanged(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic) {
super.onCharacteristicChanged(gatt, characteristic);
Log.d(CHARACTERISTICS_CHANGED_TAG, "Received from Characteristic UUID");
}
#Override
public void onCharacteristicWrite(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic, int status) {
super.onCharacteristicWrite(gatt, characteristic, status);
Log.d("onCharacteristicWrite", "Value is written...");
}
#Override
public void onDescriptorWrite(BluetoothGatt gatt, BluetoothGattDescriptor descriptor, int status) {
super.onDescriptorWrite(gatt, descriptor, status);
Log.d("onDescriptorWrite", "Descriptior is written...");
Log.d("onDescriptorWrite" , "" + mBluetoothGatt.readDescriptor(descriptor));
}
#Override
public void onDescriptorRead(BluetoothGatt gatt, BluetoothGattDescriptor descriptor, int status) {
super.onDescriptorRead(gatt, descriptor, status);
Log.d("onDescriptorRead" , "" + status);
}
#Override
public void onCharacteristicRead(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic, int status) {
super.onCharacteristicRead(gatt, characteristic, status);
}
};
Enabling The Notifications:
private boolean enableNotificationsForCharacteristic(BluetoothGattCharacteristic characteristic) {
BluetoothGattDescriptor descriptor = characteristic.getDescriptor(UUID.fromString("00002902-0000-1000-8000-00805f9b34fb"));
descriptor.setValue(BluetoothGattDescriptor.ENABLE_NOTIFICATION_VALUE);
if (mBluetoothGatt != null) {
mBluetoothGatt.setCharacteristicNotification(characteristic, true);
if (mBluetoothGatt.writeDescriptor(descriptor)) {
return true;
}
}
return false;
}
Writing to Characteristic:
private boolean writeToCharacteristic(BluetoothGattService service, BluetoothGattCharacteristic characteristic, byte[] aValue, boolean aWithResponse) {
boolean ret = false;
if (service != null) {
if (characteristic != null) {
characteristic.setValue(aValue);
characteristic.setWriteType(aWithResponse ? BluetoothGattCharacteristic.WRITE_TYPE_DEFAULT : BluetoothGattCharacteristic.WRITE_TYPE_NO_RESPONSE);
ret = mBluetoothGatt.writeCharacteristic(characteristic);
} else {
Log.e(TAG, "writeToCharacteristic() - Characteristic is null! " + service + " - " + characteristic);
}
} else {
Log.e(TAG, "writeToCharacteristic() - Service is null! " + service);
}
return ret;
}
What i am expecting:
After setting notification descriptor, i am getting a GATT_SUCCESS but when i am writing a characteristic, it is not triggering onCharacteristicChanged(). I am expecting it to trigger so that i can read the notification response. The device is behaving properly because i have confirmed the notification using Nordic Connect App
What have i tried:
Tried verifying the descriptor, to see if it is being written properly. It does.
Cross checking the name of services and characteristics. They are all fine.
Tried putting delay before write descriptor. It is being written properly.
Can anyone help me? Why it is not triggering onCharacteristicChanged?

android 4.3 Bluetooth ble don't called onCharacteristicRead() after write operation performed

I want to perform read and write operation with bluetooth peripheral.I have write sample application in which after giving particular input it give me output but inside code onCharacteristicRead not get called after onCharacteristicWrite. Please help me out.
This is my code
BluetoothGattCharacteristic WriteCharacteristic =null;
BluetoothGattCharacteristic ReadCharacteristic =null;
private BluetoothGattCallback mGattCallback = new BluetoothGattCallback() {
/* State Machine Tracking */
private int mState = 0;
private void reset() { mState = 0; }
private void advance() {
mState++;
}
public void onReliableWriteCompleted(BluetoothGatt gatt, int status) {
Log.e("onReliableWriteCompleted", "Called");
};
#Override
public void onConnectionStateChange(BluetoothGatt gatt, int status, int newState) {
Log.d(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();
//String servicename = gatt.getService(BATTERY_DATA_CHAR).toString();
//System.out.println(servicename);
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
*/
connectedDevice = null;
mHandler.sendEmptyMessage(MSG_CLEAR);
} else if (status != BluetoothGatt.GATT_SUCCESS) {
/*
* If there is a failure at any stage, simply disconnect
*/
gatt.disconnect();
connectedDevice = null;
}
}
#Override
public void onServicesDiscovered(BluetoothGatt gatt, int status) {
Log.d(TAG, "Services Discovered: "+status);
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();
String test="";
List<BluetoothGattService> strname = gatt.getServices();
String servicename =DINSTANCE_SERVICE.toString();
for(int count=0;count<strname.size();count++)
{
if(servicename.equalsIgnoreCase(strname.get(count).getUuid().toString()))
{
ReadCharacteristic = gatt.getService(DINSTANCE_SERVICE).getCharacteristic(DISTAINCE_READ_DATA);
WriteCharacteristic = gatt.getService(DINSTANCE_SERVICE).getCharacteristic(DISTANCE_WRITE_DATA);
test="123";
//characteristic.getStringValue(18);
//byte bbb[] = characteristic.getValue();
// gatt.readCharacteristic(characteristic);
/*String strInput = "012072";
byte passvalues[] = strInput.getBytes();
WriteCharacteristic.setValue(passvalues);
gatt.writeCharacteristic(WriteCharacteristic);*/
WriteCharacteristic.setWriteType(BluetoothGattCharacteristic.WRITE_TYPE_DEFAULT);
//tChar.setWriteType(BluetoothGattCharacteristic.WRITE_TYPE_DEFAULT);
WriteCharacteristic.setValue(012072, BluetoothGattCharacteristic.FORMAT_SINT32, 0);
gatt.writeCharacteristic(WriteCharacteristic);
break;
}
}
System.out.println(servicename);
}
public void onDescriptorRead(BluetoothGatt gatt, BluetoothGattDescriptor descriptor, int status)
{
Log.e("onDescriptorRead","Read method gets called.");
};
#Override
public void onCharacteristicRead(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic, int status) {
//For each read, pass the data up to the UI thread to update the display
byte bbb[] = characteristic.getValue();
if (HUMIDITY_DATA_CHAR.equals(characteristic.getUuid())) {
mHandler.sendMessage(Message.obtain(null, MSG_HUMIDITY, characteristic));
}
if (PRESSURE_DATA_CHAR.equals(characteristic.getUuid())) {
mHandler.sendMessage(Message.obtain(null, MSG_PRESSURE, characteristic));
}
if (PRESSURE_CAL_CHAR.equals(characteristic.getUuid())) {
mHandler.sendMessage(Message.obtain(null, MSG_PRESSURE_CAL, characteristic));
}
if(DISTAINCE_READ_DATA.equals(characteristic.getUuid()))
{
mHandler.sendMessage(Message.obtain(null, MSG_BATTERY, characteristic));
}
if(BATTERY_READ_CHAR.equals(characteristic.getUuid()))
{
mHandler.sendMessage(Message.obtain(null, MSG_BATTERY, characteristic));
}
//After reading the initial value, next we enable notifications
//setNotifyNextSensor(gatt);
}
#Override
public void onCharacteristicWrite(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic, int status)
{
//After writing the enable flag, next we read the initial value
// readNextSensor(gatt);
try {
if (status != BluetoothGatt.GATT_SUCCESS)
throw new AssertionError("Error on char write");
super.onCharacteristicWrite(gatt, characteristic, status);
if (characteristic.getUuid().equals(DISTANCE_WRITE_DATA)) {
BluetoothGattService syncService = gatt.getService(DINSTANCE_SERVICE);
BluetoothGattCharacteristic tChar = syncService.getCharacteristic(DISTANCE_WRITE_DATA);
ReadCharacteristic = syncService.getCharacteristic(DISTAINCE_READ_DATA);
if (tChar == null)throw new AssertionError("characteristic null when sync time!");
tChar.setValue(012072,BluetoothGattCharacteristic.FORMAT_SINT32, 0);
gatt.readCharacteristic(ReadCharacteristic);
// gatt.readDescriptor(null);
}
} catch (AssertionError e) {
e.printStackTrace();
}
}
#Override
public void onCharacteristicChanged(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic) {
/*
* 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.
*/
if (HUMIDITY_DATA_CHAR.equals(characteristic.getUuid())) {
mHandler.sendMessage(Message.obtain(null, MSG_HUMIDITY, characteristic));
}
if (PRESSURE_DATA_CHAR.equals(characteristic.getUuid())) {
mHandler.sendMessage(Message.obtain(null, MSG_PRESSURE, characteristic));
}
if (PRESSURE_CAL_CHAR.equals(characteristic.getUuid())) {
mHandler.sendMessage(Message.obtain(null, MSG_PRESSURE_CAL, characteristic));
}
}
#Override
public void onDescriptorWrite(BluetoothGatt gatt, BluetoothGattDescriptor descriptor, int status) {
//Once notifications are enabled, we move to the next sensor and start over with enable
String strInput = "012072";
byte passvalues[] = strInput.getBytes();
descriptor.setValue(passvalues);
advance();
Log.e("onDescriptorWrite", "called");
//enableNextSensor(gatt);
}
#Override
public void onReadRemoteRssi(BluetoothGatt gatt, int rssi, int status)
{
Log.e("onReadRemoteRssi", "called");
Log.d(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);
}
}
};

Here you can set up (subscribe) to the charactersitic through either notification or indication by calling:
mBluetoothGatt.setCharacteristicNotification(characteristic, true)
mBluetoothGatt.readCharacteristic(characteristic);
from here