..
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:orphan:
:breadcrumbs: <a href="../../index.html">Home</a> / <a href="../../index.html#software-perl">Software</a> / Perl - Dust Detector Bricklet

.. |device_identifier_constant| replace:: There is also a :ref:`constant <dust_detector_bricklet_perl_constants>` for the device identifier of this Bricklet.

.. _dust_detector_bricklet_perl:

Perl - Dust Detector Bricklet
=============================

.. note::
 This Bricklet is currently in the prototype stage and the software/hardware
 as well as the documentation is in an incomplete state.


This is the description of the :ref:`Perl API bindings <api_bindings_perl>` for the :ref:`Dust Detector Bricklet <dust_detector_bricklet>`. General information and technical
specifications for the Dust Detector Bricklet are summarized in its :ref:`hardware description
<dust_detector_bricklet_description>`.

An :ref:`installation guide <api_bindings_perl_install>` for the Perl API
bindings is part of their general description.

.. _dust_detector_bricklet_perl_examples:


Examples
--------

The example code below is `Public Domain (CC0 1.0)
<http://creativecommons.org/publicdomain/zero/1.0/>`__.

Simple
^^^^^^

`Download (example_simple.pl) <https://github.com/Tinkerforge/dust-detector-bricklet/raw/master/software/examples/perl/example_simple.pl>`__

.. literalinclude:: DustDetector_Bricklet_Perl_example_simple.pl
 :language: perl
 :linenos:
 :tab-width: 4

Callback
^^^^^^^^

`Download (example_callback.pl) <https://github.com/Tinkerforge/dust-detector-bricklet/raw/master/software/examples/perl/example_callback.pl>`__

.. literalinclude:: DustDetector_Bricklet_Perl_example_callback.pl
 :language: perl
 :linenos:
 :tab-width: 4

Threshold
^^^^^^^^^

`Download (example_threshold.pl) <https://github.com/Tinkerforge/dust-detector-bricklet/raw/master/software/examples/perl/example_threshold.pl>`__

.. literalinclude:: DustDetector_Bricklet_Perl_example_threshold.pl
 :language: perl
 :linenos:
 :tab-width: 4

.. _dust_detector_bricklet_perl_api:

API
---

Generally, every subroutine of the Perl bindings can report an error as
``Tinkerforge::Error`` object via ``croak()``. The object has a
``get_code()`` and a ``get_message()`` subroutine. There are different
error code:

* Error->ALREADY_CONNECTED = 11
* Error->NOT_CONNECTED = 12
* Error->CONNECT_FAILED = 13
* Error->INVALID_FUNCTION_ID = 21
* Error->TIMEOUT = 31
* Error->INVALID_PARAMETER = 41
* Error->FUNCTION_NOT_SUPPORTED = 42
* Error->UNKNOWN_ERROR = 43

All methods listed below are thread-safe.




Basic Functions
^^^^^^^^^^^^^^^


.. perl:function:: BrickletDustDetector->new($uid, $ipcon)

 :param $uid: string
 :param $ipcon: IPConnection
 :rtype: BrickletDustDetector

 Creates an object with the unique device ID ``$uid``:

 .. code-block:: perl

    $dust_detector = BrickletDustDetector->new("YOUR_DEVICE_UID", $ipcon);

 This object can then be used after the IP Connection is connected
 (see examples :ref:`above <dust_detector_bricklet_perl_examples>`).


.. perl:function:: BrickletDustDetector->get_dust_density()

 :rtype: int

 Returns the dust density in µg/m³.
 
 If you want to get the dust density periodically, it is recommended 
 to use the callback :perl:attr:`CALLBACK_DUST_DENSITY <BrickletDustDetector->CALLBACK_DUST_DENSITY>` and set the period with 
 :perl:func:`set_dust_density_callback_period() <BrickletDustDetector->set_dust_density_callback_period>`.
 


Advanced Functions
^^^^^^^^^^^^^^^^^^

.. perl:function:: BrickletDustDetector->set_moving_average($average)

 :param $average: int
 :rtype: undef

 Sets the length of a `moving averaging <http://en.wikipedia.org/wiki/Moving_average>`__ 
 for the dust_density.
 
 Setting the length to 0 will turn the averaging completely off. With less
 averaging, there is more noise on the data.
 
 The range for the averaging is 0-100.
 
 The default value is 100.
 
.. perl:function:: BrickletDustDetector->get_moving_average()

 :rtype: int

 Returns the length moving average as set by :perl:func:`set_moving_average() <BrickletDustDetector->set_moving_average>`.
 
.. perl:function:: BrickletDustDetector->get_api_version()

 :rtype: [int, int, int]

 Returns the version of the API definition (major, minor, revision) implemented
 by this API bindings. This is neither the release version of this API bindings
 nor does it tell you anything about the represented Brick or Bricklet.
 
.. perl:function:: BrickletDustDetector->get_response_expected($function_id)

 :param $function_id: int
 :rtype: bool

 Returns the response expected flag for the function specified by the function
 ID parameter. It is *true* if the function is expected to send a response,
 *false* otherwise.
 
 For getter functions this is enabled by default and cannot be disabled,
 because those functions will always send a response. For callback configuration
 functions it is enabled by default too, but can be disabled by
 :perl:func:`set_response_expected() <BrickletDustDetector->set_response_expected>`. For setter functions it is disabled by default
 and can be enabled.
 
 Enabling the response expected flag for a setter function allows to detect
 timeouts and other error conditions calls of this setter as well. The
 device will then send a response for this purpose. If this flag is disabled for
 a setter function then no response is send and errors are silently ignored,
 because they cannot be detected.
 
 See :perl:func:`set_response_expected() <BrickletDustDetector->set_response_expected>`
 for the list of function ID constants available for this function.
 
.. perl:function:: BrickletDustDetector->set_response_expected($function_id, $response_expected)

 :param $function_id: int
 :param $response_expected: bool
 :rtype: undef

 Changes the response expected flag of the function specified by the
 function ID parameter. This flag can only be changed for setter (default value:
 *false*) and callback configuration functions (default value: *true*). For
 getter functions it is always enabled and callbacks it is always disabled.
 
 Enabling the response expected flag for a setter function allows to detect
 timeouts and other error conditions calls of this setter as well. The
 device will then send a response for this purpose. If this flag is disabled for
 a setter function then no response is send and errors are silently ignored,
 because they cannot be detected.
 
 The following function ID constants are available for this function:
 
 * BrickletDustDetector->FUNCTION_SET_DUST_DENSITY_CALLBACK_PERIOD = 2
 * BrickletDustDetector->FUNCTION_SET_DUST_DENSITY_CALLBACK_THRESHOLD = 4
 * BrickletDustDetector->FUNCTION_SET_DEBOUNCE_PERIOD = 6
 * BrickletDustDetector->FUNCTION_SET_MOVING_AVERAGE = 10
 
.. perl:function:: BrickletDustDetector->set_response_expected_all($response_expected)

 :param $response_expected: bool
 :rtype: undef

 Changes the response expected flag for all setter and callback configuration
 functions of this device at once.
 
.. perl:function:: BrickletDustDetector->get_identity()

 :rtype: [string, string, char, [int, int, int], [int, int, int], int]

 Returns the UID, the UID where the Bricklet is connected to, 
 the position, the hardware and firmware version as well as the
 device identifier.
 
 The position can be 'a', 'b', 'c' or 'd'.
 
 The device identifier numbers can be found :ref:`here <device_identifier>`.
 |device_identifier_constant|
 
 The returned array contains the elements ``uid``, ``connected_uid``, ``position``, ``hardware_version``, ``firmware_version`` and ``device_identifier``.



Callback Configuration Functions
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^


.. perl:function:: BrickletDustDetector->register_callback($id, $callback)

 :param $id: int
 :param $callback: string
 :rtype: undef

 Registers a callback with ID ``$id`` to the function named ``$callback``. The
 available IDs with corresponding function signatures are listed
 :ref:`below <dust_detector_bricklet_perl_callbacks>`.


.. perl:function:: BrickletDustDetector->set_dust_density_callback_period($period)

 :param $period: int
 :rtype: undef

 Sets the period in ms with which the :perl:attr:`CALLBACK_DUST_DENSITY <BrickletDustDetector->CALLBACK_DUST_DENSITY>` callback is triggered
 periodically. A value of 0 turns the callback off.
 
 :perl:attr:`CALLBACK_DUST_DENSITY <BrickletDustDetector->CALLBACK_DUST_DENSITY>` is only triggered if the dust density has changed since the
 last triggering.
 
 The default value is 0.
 
.. perl:function:: BrickletDustDetector->get_dust_density_callback_period()

 :rtype: int

 Returns the period as set by :perl:func:`set_dust_density_callback_period() <BrickletDustDetector->set_dust_density_callback_period>`.
 
.. perl:function:: BrickletDustDetector->set_dust_density_callback_threshold($option, $min, $max)

 :param $option: char
 :param $min: int
 :param $max: int
 :rtype: undef

 Sets the thresholds for the :perl:attr:`CALLBACK_DUST_DENSITY_REACHED <BrickletDustDetector->CALLBACK_DUST_DENSITY_REACHED>` callback. 
 
 The following options are possible:
 
 .. csv-table::
  :header: "Option", "Description"
  :widths: 10, 100
 
  "'x'",    "Callback is turned off"
  "'o'",    "Callback is triggered when the dust density value is *outside* the min and max values"
  "'i'",    "Callback is triggered when the dust density value is *inside* the min and max values"
  "'<'",    "Callback is triggered when the dust density value is smaller than the min value (max is ignored)"
  "'>'",    "Callback is triggered when the dust density value is greater than the min value (max is ignored)"
 
 The default value is ('x', 0, 0).
 
 The following constants are available for this function:
 
 * BrickletDustDetector->THRESHOLD_OPTION_OFF = 'x'
 * BrickletDustDetector->THRESHOLD_OPTION_OUTSIDE = 'o'
 * BrickletDustDetector->THRESHOLD_OPTION_INSIDE = 'i'
 * BrickletDustDetector->THRESHOLD_OPTION_SMALLER = '<'
 * BrickletDustDetector->THRESHOLD_OPTION_GREATER = '>'
 
.. perl:function:: BrickletDustDetector->get_dust_density_callback_threshold()

 :rtype: [char, int, int]

 Returns the threshold as set by :perl:func:`set_dust_density_callback_threshold() <BrickletDustDetector->set_dust_density_callback_threshold>`.
 
 The following constants are available for this function:
 
 * BrickletDustDetector->THRESHOLD_OPTION_OFF = 'x'
 * BrickletDustDetector->THRESHOLD_OPTION_OUTSIDE = 'o'
 * BrickletDustDetector->THRESHOLD_OPTION_INSIDE = 'i'
 * BrickletDustDetector->THRESHOLD_OPTION_SMALLER = '<'
 * BrickletDustDetector->THRESHOLD_OPTION_GREATER = '>'
 
 The returned array contains the elements ``option``, ``min`` and ``max``.

.. perl:function:: BrickletDustDetector->set_debounce_period($debounce)

 :param $debounce: int
 :rtype: undef

 Sets the period in ms with which the threshold callback
 
 * :perl:attr:`CALLBACK_DUST_DENSITY_REACHED <BrickletDustDetector->CALLBACK_DUST_DENSITY_REACHED>`
 
 is triggered, if the threshold
 
 * :perl:func:`set_dust_density_callback_threshold() <BrickletDustDetector->set_dust_density_callback_threshold>`
 
 keeps being reached.
 
 The default value is 100.
 
.. perl:function:: BrickletDustDetector->get_debounce_period()

 :rtype: int

 Returns the debounce period as set by :perl:func:`set_debounce_period() <BrickletDustDetector->set_debounce_period>`.
 


.. _dust_detector_bricklet_perl_callbacks:

Callbacks
^^^^^^^^^

Callbacks can be registered to receive
time critical or recurring data from the device. The registration is done
with the :perl:func:`register_callback() <BrickletDustDetector->register_callback>` function of
the device object. The first parameter is the callback ID and the second
parameter the callback function name:

.. code-block:: perl

    sub my_callback
    {
        print "@_[0]";
    }

    $dust_detector->register_callback(BrickletDustDetector->CALLBACK_EXAMPLE, 'my_callback')

The callback function will be called from an internal thread of the
IP Connection. In contrast to many other programming languages, variables are
not automatically shared between threads in Perl. If you want to share a global
variable between a callback function and the rest for your program it has to be
marked as ``:shared``. See the documentation of the `threads::shared
<http://perldoc.perl.org/threads/shared.html>`__ Perl module for more details.

The available constants with inherent number and type of parameters are
described below.

.. note::
 Using callbacks for recurring events is *always* preferred
 compared to using getters. It will use less USB bandwidth and the latency
 will be a lot better, since there is no round trip time.

.. perl:attribute:: BrickletDustDetector->CALLBACK_DUST_DENSITY

 :param $dust_density: int


 This callback is triggered periodically with the period that is set by
 :perl:func:`set_dust_density_callback_period() <BrickletDustDetector->set_dust_density_callback_period>`. The parameter is the 
 dust density of the sensor.
 
 :perl:attr:`CALLBACK_DUST_DENSITY <BrickletDustDetector->CALLBACK_DUST_DENSITY>` is only triggered if the dust density value has changed since the
 last triggering.
 
.. perl:attribute:: BrickletDustDetector->CALLBACK_DUST_DENSITY_REACHED

 :param $dust_density: int


 This callback is triggered when the threshold as set by
 :perl:func:`set_dust_density_callback_threshold() <BrickletDustDetector->set_dust_density_callback_threshold>` is reached.
 The parameter is the dust density of the sensor.
 
 If the threshold keeps being reached, the callback is triggered periodically
 with the period as set by :perl:func:`set_debounce_period() <BrickletDustDetector->set_debounce_period>`.
 


.. _dust_detector_bricklet_perl_constants:

Constants
^^^^^^^^^

.. perl:attribute:: BrickletDustDetector->DEVICE_IDENTIFIER

 This constant is used to identify a Dust Detector Bricklet.

 The :perl:func:`get_identity() <BrickletDustDetector->get_identity>` function and the
 :perl:attr:`CALLBACK_ENUMERATE <IPConnection.CALLBACK_ENUMERATE>`
 callback of the IP Connection have a ``device_identifier`` parameter to specify
 the Brick's or Bricklet's type.

