GATT characteristic not change value

Question

BLE device (pulsometer) value in characteristic always the same. The signal goes to onCharacteristicChanged but the value does not change, tried to get the value in different ways.

@Override
public void onServicesDiscovered(BluetoothGatt gatt, int status) {
super.onServicesDiscovered(gatt, status);
    BluetoothGattCharacteristic characteristic3 = gatt.getService(UUID.fromString("0000180f-0000-1000-8000-00805f9b34fb"))
                    .getCharacteristic(UUID.fromString("00002a19-0000-1000-8000-00805f9b34fb"));
    gatt.setCharacteristicNotification(characteristic3, true);
    gatt.readCharacteristic(characteristic3);
}

@Override
public void onCharacteristicRead(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic, int status) {
    super.onCharacteristicRead(gatt, characteristic, status);
    UUID uuid = UUID.fromString("00002902-0000-1000-8000-00805f9b34fb");
    BluetoothGattDescriptor descriptor = characteristic.getDescriptor(uuid);
    descriptor.setValue(BluetoothGattDescriptor.ENABLE_NOTIFICATION_VALUE);
    gatt.writeDescriptor(descriptor);
}

@Override
public void onCharacteristicChanged(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic) {
    super.onCharacteristicChanged(gatt, characteristic);
    Log.e(TAG, "pulse: " + characteristic.getIntValue(BluetoothGattCharacteristic.FORMAT_UINT8, 0));
}

logcat

check this https://github.com/devunwired/accessory-samples/blob/master/BluetoothGatt/src/com/example/bluetoothgatt/MainActivity.java if it helps. — Raghunandan, May 03 '17 at 07:14

score 0 · Answer 1 · edited May 23 '17 at 11:33

Decision:

@Override
    public void onServicesDiscovered(BluetoothGatt gatt, int status) {
    super.onServicesDiscovered(gatt, status);

    BluetoothGattCharacteristic characteristic2 = gatt.getService(UUID.fromString("0000180d-0000-1000-8000-00805f9b34fb"))
                    .getCharacteristic(UUID.fromString("00002a37-0000-1000-8000-00805f9b34fb"));

    gatt.setCharacteristicNotification(characteristic2, true);

    // 1 !!!!!!
    UUID uuid = UUID.fromString("00002902-0000-1000-8000-00805f9b34fb");
    BluetoothGattDescriptor descriptor = characteristic2.getDescriptor(uuid);
    descriptor.setValue(BluetoothGattDescriptor.ENABLE_NOTIFICATION_VALUE);
    gatt.writeDescriptor(descriptor);

    // 2 !!!!!!
    gatt.readCharacteristic(characteristic2);
}

This Helped , change UUIDs (it can be found), and lib get value - SmartGattLib, and all working )

GATT characteristic not change value

1 Answers1