Ble-getting error code - 128 while writing to characterstic

Question

I am using following react library react-native-ble-manager

I am trying to perform read and write operations on BLE device.I am successfully able to perform read operation. But I am getting error code 128 while writing to BLE device.

first, I am enabling notification for characteristic -

BleManager.startNotification(peripheralId, serviceId, characteristicId)

Writing is like this -
converting 'hex' value to base64 string -

  const base64String = new Buffer('0x00B00050D0', 'hex').toString('base64');

  BleManager.write(peripheralId, serviceId, characteristicId, base64Value)

Write operation return error code -128

:(

UPDATE -- This is code snippet to start notification and write value- complete file can be found here- BluetoothLeService.java

public void writeCharacteristic(BleCharacteristic bleCharacteristic, String inputValue) {

    if (mBluetoothAdapter == null || mBluetoothGatt == null) {
        Log.w(TAG, "BluetoothAdapter not initialized");
        return;
    }

    if (!bleCharacteristic.isNotificationStarted()) {
        Log.w(TAG, "Notification not started please start notification");
        return;
    }

    BluetoothGattCharacteristic bluetoothGattCharacteristic = bleCharacteristic.getBluetoothGattCharacteristic();
    bluetoothGattCharacteristic.setValue(inputValue);
    mBluetoothGatt.writeCharacteristic(bluetoothGattCharacteristic);
}

public void setCharacteristicNotification(BleCharacteristic bleCharacteristic) {
    if (mBluetoothAdapter == null || mBluetoothGatt == null) {
        Log.w(TAG, "BluetoothAdapter not initialized");
        return;
    }
    boolean enable = !bleCharacteristic.isNotificationStarted();
    Log.d(TAG, "setCharacteristicNotification(device=" + mBluetoothDeviceAddress + ", UUID="
            + bleCharacteristic.getUUID().toString() + ", enable=" + enable + " )");
    BluetoothGattCharacteristic characteristic = mBluetoothGatt.getService(bleCharacteristic.getServiceUUID()).getCharacteristic(bleCharacteristic.getUUID());
    mBluetoothGatt.setCharacteristicNotification(characteristic, enable);
    BluetoothGattDescriptor descriptor = characteristic.getDescriptor(UUID.fromString(SampleGattAttributes.CLIENT_CHARACTERISTIC_CONFIG));
    descriptor.setValue(enable ? BluetoothGattDescriptor.ENABLE_NOTIFICATION_VALUE : new byte[]{0x00, 0x00});
    boolean result = mBluetoothGatt.writeDescriptor(descriptor);
    bleCharacteristic.setNotificationStarted(result);
    Log.d(TAG, "setCharacteristicNotification(device=" + mBluetoothDeviceAddress + ", UUID="
            + bleCharacteristic.getUUID().toString() + ", enabled=" + result + " )");
}

Answer 1

This is a no resources error. Are you sure you wrote the descriptor? If you don't set the descriptor (BluetoothGattDescriptor) and just call write, you'll get this error.

Here is an example:

protected static final UUID CHARACTERISTIC_UPDATE_NOTIFICATION_DESCRIPTOR_UUID = UUID.fromString("00002902-0000-1000-8000-00805f9b34fb");

public boolean setCharacteristicNotification(BluetoothDevice device, UUID serviceUuid, UUID characteristicUuid,
        boolean enable) {
    if (IS_DEBUG)
        Log.d(TAG, "setCharacteristicNotification(device=" + device.getName() + device.getAddress() + ", UUID="
                + characteristicUuid + ", enable=" + enable + " )");
    BluetoothGatt gatt = mGattInstances.get(device.getAddress()); //I just hold the gatt instances I got from connect in this HashMap
    BluetoothGattCharacteristic characteristic = gatt.getService(serviceUuid).getCharacteristic(characteristicUuid);
    gatt.setCharacteristicNotification(characteristic, enable);
    BluetoothGattDescriptor descriptor = characteristic.getDescriptor(CHARACTERISTIC_UPDATE_NOTIFICATION_DESCRIPTOR_UUID);
    descriptor.setValue(enable ? BluetoothGattDescriptor.ENABLE_NOTIFICATION_VALUE : new byte[] { 0x00, 0x00 });
    return gatt.writeDescriptor(descriptor); //descriptor write operation successfully started? 
}

Source