..
  This file is part of GNU TALER.
  Copyright (C) 2014-2026 Taler Systems SA

  TALER is free software; you can redistribute it and/or modify it under the
  terms of the GNU Affero General Public License as published by the Free Software
  Foundation; either version 2.1, or (at your option) any later version.

  TALER is distributed in the hope that it will be useful, but WITHOUT ANY
  WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
  A PARTICULAR PURPOSE. See the GNU Affero General Public License for more details.

  You should have received a copy of the GNU Affero General Public License along with
  TALER; see the file COPYING. If not, see <http://www.gnu.org/licenses/>


.. _pos_displays:

Connect a Taler Payment Device
==============================

.. contents::
  :depth: 1
  :local:

Connect a Taler Payment Device so customers can scan the payment QR code or tap
their phone to pay by NFC. You can connect it by Bluetooth or USB.

Open **Settings → Manage payment options → GNU Taler**. The **Manage displays**
section lists your connected devices.

.. figure:: ../../images/pos/tutorial-updates/add-display.png
   :alt: GNU Taler settings with Add device (1) and Check USB connection (2).
   :width: 70%
   :align: center

   Manage your Taler Payment Devices in GNU Taler settings.

Pairing over Bluetooth
----------------------

Keep the Taler Payment Device powered on and near the POS.

1. Press **Add device** (1), then choose **Bluetooth display**.
2. If requested, allow nearby-device access and turn on Bluetooth. Older
   Android versions may also require location to be enabled for discovery.
3. When the POS asks you to open the device settings, swipe left on its screen
   and tap its settings icon. Press **Next** on the POS.
4. On the device, open **Bluetooth → Pair a POS**. Press **Next** on the POS.
5. Select the matching **Taler ...** device (1) from the search results.
   If it is missing, keep the device in pairing mode and press **Search again**.
6. In Android's pairing prompt, enter the code shown on the device.
   Complete this while the device's pairing window is open.
7. Wait for **Display connected**, then press **Done**.

.. figure:: ../../images/pos/tutorial-updates/connection-type.png
   :alt: Add device dialog offering Bluetooth display or USB device.
   :width: 70%
   :align: center

   Select the connection type.

.. figure:: ../../images/pos/tutorial-updates/choose-display.png
   :alt: Choose your display dialog with the Taler Payment Device marked (1).
   :width: 70%
   :align: center

   Select the name shown on your Taler Payment Device.

.. figure:: ../../images/pos/tutorial-updates/pairing.png
   :alt: Connect display dialog instructing the user to enter the code from the device in the Android pairing prompt.
   :width: 70%
   :align: center

   Follow the instructions to pair the device.

You can connect one Taler Payment Device at a time over Bluetooth. If you add
another, the POS asks you to replace the current one. Once paired, the device
reconnects without a new code.

Testing and reconnecting
------------------------

1. On the connected device's card, press **Test display** (1).
2. Check that the device shows a test QR code and clears it after about five
   seconds. The test does not create a payment.
3. Create a payment when you are ready for a sale and check that the device
   shows that payment's QR code. The POS's own QR code remains available.

.. figure:: ../../images/pos/tutorial-updates/connected-display.png
   :alt: Connected Taler Payment Device with Test display (1) and Remove display (2).
   :width: 70%
   :align: center

   Test the screen before using it with a customer.

If the device disconnects, power it on and bring it nearby, then use
**Reconnect** on its card. If the POS reports that a link is too long or could
not be sent, use the QR code on the POS for that payment.

Removing or pairing the device again
------------------------------------

To stop using a Taler Payment Device on this POS, press **Remove display** (2) and confirm.
The device remains paired in Android's Bluetooth settings.

If pairing no longer works, follow **Pair again**:

1. Forget the device in Android's Bluetooth settings, then return to the POS.
2. On the device, open **Bluetooth** and choose **Forget this POS** for the old POS
   if it is listed.
3. On the device, choose **Pair a POS** again.
4. Follow the POS pairing steps and enter the new code when prompted.

Follow these steps too when moving the device to another POS.

Connecting over USB
-------------------

1. Connect a Taler Payment Device to the Android POS using a USB cable.
2. Open **GNU Taler → Manage displays** and press **Check USB connection** (2),
   or use **Add device → USB device**.
3. Grant Android's USB access permission if requested.
4. Check the displayed connection status. If necessary, reconnect the cable
   and press **Check connection**.

.. figure:: ../../images/pos/tutorial-updates/usb-display.png
   :alt: Check USB connection dialog reporting a connected Taler Payment Device.
   :width: 70%
   :align: center

   Verify USB access and connection before showing a payment.

Check that the device clears the QR code and NFC link when you leave a
payment or refund.

.. topic:: Next step

   Continue with :ref:`pos_orders` to try the connected device with an order.