.. _nrf_desktop_passkey:

Passkey module
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Use the passkey module to handle numeric passkey input.
The input handling is based on button presses.

Module events
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.. include:: ../../../../../../../applications/nrf_desktop/doc/event_propagation.rst
    :start-after: table_passkey_start
    :end-before: table_passkey_end

.. note::
    |nrf_desktop_module_event_note|

Configuration
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The passkey input handling is based on ``button_event``.

To configure the passkey module, complete the following steps:

1. Enable and configure the :ref:`caf_buttons`.
#. Enable the passkey module by using the :ref:`CONFIG_DESKTOP_PASSKEY_BUTTONS <config_desktop_app_options>` option.
#. Define the maximum number of digits in the passkey by using the :ref:`CONFIG_DESKTOP_PASSKEY_MAX_LEN <config_desktop_app_options>` option.
#. Define the IDs of the keys used by the passkey module in the :file:`passkey_buttons_def.h` file located in the board-specific directory in the :file:`configuration` directory.
   You must define the IDs of the following keys:

   * Keys used to input the digits.
   * Keys used to confirm the input.
   * Keys used to remove the last digit (short-press removes only the last digit, but if the key is held for longer than 2 seconds, the whole input is cleared).

   You can define multiple sets of keys used to input the digits, but every set should contain keys used to input every digit.
   This is to ensure that the user will be able to input the passkey.
   The index of the key ID in the input configuration array represents the digit.

The example configuration of the module can be found in the :file:`configuration/nrf52kbd_nrf52832/passkey_buttons_def.h` file.

Implementation details
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The passkey module reacts to ``passkey_req_event`` by switching between the idle and the active state:

* The user input is handled only in the active state.
  Key presses are remembered in an array.
* When the input is confirmed, the ``passkey_input_event`` that contains the user input is submitted and the module switches to the idle state.