BLE: How to send Write Request instead of Write Command?

Question

I'm trying to send packets to bluetooth low energy (BLE) device from smartphone (Android App)

I know how to send Write Command:

something like this:

public void onServicesDiscovered(final BluetoothGatt gatt, int status) {
        List<BluetoothGattService> services = gatt.getServices();
        for (BluetoothGattService service : services) {
            for (final BluetoothGattCharacteristic characteristic : service.getCharacteristics()) {
                if (characteristic.getUuid().toString().equals(CONTROL_UUID)) {
                    boolean setValue = characteristic.setValue(new byte[]{/*..BYTES.*/});
                    boolean writeCharacteristic = gatt.writeCharacteristic(characteristic);
                }
            }
        }
    }

when I see this sent command in Wireshark (sniffing app), I see something like this

but I also need to send something like this (not write command, but write request)

official app which controls that devices sends this write request only once after connecting

seems without it I would not be able to control that device

so before I would send any write command I need to send this write request first

Answer 1

See https://developer.android.com/reference/android/bluetooth/BluetoothGattCharacteristic.html#setWriteType(int)

You need to use the WRITE_TYPE_DEFAULT.