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:breadcrumbs: <a href="../../index.html">Home</a> / <a href="../../index.html#software-c">Software</a> / C/C++ - Piezo Speaker Bricklet

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

.. _piezo_speaker_bricklet_c:

C/C++ - Piezo Speaker Bricklet
==============================

This is the description of the :ref:`C/C++ API bindings <api_bindings_c>` for the :ref:`Piezo Speaker Bricklet <piezo_speaker_bricklet>`. General information and technical
specifications for the Piezo Speaker Bricklet are summarized in its :ref:`hardware description
<piezo_speaker_bricklet_description>`.

An :ref:`installation guide <api_bindings_c_install>` for the C/C++ API
bindings is part of their general description.

.. _piezo_speaker_bricklet_c_examples:


Examples
--------

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

Beep
^^^^

`Download (example_beep.c) <https://github.com/Tinkerforge/piezo-speaker-bricklet/raw/master/software/examples/c/example_beep.c>`__

.. literalinclude:: PiezoSpeaker_Bricklet_C_example_beep.c
 :language: c
 :linenos:
 :tab-width: 4

Morse Code
^^^^^^^^^^

`Download (example_morse_code.c) <https://github.com/Tinkerforge/piezo-speaker-bricklet/raw/master/software/examples/c/example_morse_code.c>`__

.. literalinclude:: PiezoSpeaker_Bricklet_C_example_morse_code.c
 :language: c
 :linenos:
 :tab-width: 4

.. _piezo_speaker_bricklet_c_api:

API
---

Every function of the C/C++ bindings returns an integer which describes an
error code. Data returned from the device, when a getter is called,
is handled via call by reference. These parameters are labeled with the
``ret_`` prefix.

Possible error codes are:

* E_OK = 0
* E_TIMEOUT = -1
* E_NO_STREAM_SOCKET = -2
* E_HOSTNAME_INVALID = -3
* E_NO_CONNECT = -4
* E_NO_THREAD = -5
* E_NOT_ADDED = -6 (unused since bindings version 2.0.0)
* E_ALREADY_CONNECTED = -7
* E_NOT_CONNECTED = -8
* E_INVALID_PARAMETER = -9
* E_NOT_SUPPORTED = -10
* E_UNKNOWN_ERROR_CODE = -11

as defined in :file:`ip_connection.h`.

All functions listed below are thread-safe.




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


.. c:function:: void piezo_speaker_create(PiezoSpeaker *piezo_speaker, const char *uid, IPConnection *ipcon)

 Creates the device object ``piezo_speaker`` with the unique device ID ``uid`` and adds
 it to the IPConnection ``ipcon``:

 .. code-block:: c

    PiezoSpeaker piezo_speaker;
    piezo_speaker_create(&piezo_speaker, "YOUR_DEVICE_UID", &ipcon);

 This device object can be used after the IP connection has been connected
 (see examples :ref:`above <piezo_speaker_bricklet_c_examples>`).

.. c:function:: void piezo_speaker_destroy(PiezoSpeaker *piezo_speaker)

 Removes the device object ``piezo_speaker`` from its IPConnection and destroys it.
 The device object cannot be used anymore afterwards.


.. c:function:: int piezo_speaker_beep(PiezoSpeaker *piezo_speaker, uint32_t duration, uint16_t frequency)

 Beeps with the given frequency for the duration in ms. For example: 
 If you set a duration of 1000, with a frequency value of 2000
 the piezo buzzer will beep for one second with a frequency of
 approximately 2 kHz.
 
 .. versionchanged:: 2.0.2~(Plugin)
    A duration of 0 stops the current beep if any, the frequency parameter is
    ignored. A duration of 4294967295 results in an infinite beep.
 
 The *frequency* parameter can be set between 585 and 7100.
 
 The Piezo Speaker Bricklet can only approximate the frequency, it will play
 the best possible match by applying the calibration (see :c:func:`piezo_speaker_calibrate`).
 
 The following defines are available for this function:
 
 * PIEZO_SPEAKER_BEEP_DURATION_OFF = 0
 * PIEZO_SPEAKER_BEEP_DURATION_INFINITE = 4294967295
 
.. c:function:: int piezo_speaker_morse_code(PiezoSpeaker *piezo_speaker, const char morse[60], uint16_t frequency)

 Sets morse code that will be played by the piezo buzzer. The morse code
 is given as a string consisting of "." (dot), "-" (minus) and " " (space)
 for *dits*, *dahs* and *pauses*. Every other character is ignored.
 The second parameter is the frequency (see :c:func:`piezo_speaker_beep`).
 
 For example: If you set the string "...---...", the piezo buzzer will beep
 nine times with the durations "short short short long long long short 
 short short".
 
 The maximum string size is 60.
 


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

.. c:function:: int piezo_speaker_calibrate(PiezoSpeaker *piezo_speaker, bool *ret_calibration)

 The Piezo Speaker Bricklet can play 512 different tones. This function
 plays each tone and measures the exact frequency back. The result is a
 mapping between setting value and frequency. This mapping is stored
 in the EEPROM and loaded on startup.
 
 The Bricklet should come calibrated, you only need to call this
 function (once) every time you reflash the Bricklet plugin.
 
 Returns *true* after the calibration finishes.
 
.. c:function:: int piezo_speaker_get_api_version(PiezoSpeaker *piezo_speaker, uint8_t ret_api_version[3])

 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.
 
.. c:function:: int piezo_speaker_get_response_expected(PiezoSpeaker *piezo_speaker, uint8_t function_id, bool *ret_response_expected)

 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
 :c:func:`piezo_speaker_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 :c:func:`piezo_speaker_set_response_expected`
 for the list of function ID defines available for this function.
 
.. c:function:: int piezo_speaker_set_response_expected(PiezoSpeaker *piezo_speaker, uint8_t function_id, bool response_expected)

 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 defines are available for this function:
 
 * PIEZO_SPEAKER_FUNCTION_BEEP = 1
 * PIEZO_SPEAKER_FUNCTION_MORSE_CODE = 2
 
.. c:function:: int piezo_speaker_set_response_expected_all(PiezoSpeaker *piezo_speaker, bool response_expected)

 Changes the response expected flag for all setter and callback configuration
 functions of this device at once.
 
.. c:function:: int piezo_speaker_get_identity(PiezoSpeaker *piezo_speaker, char ret_uid[8], char ret_connected_uid[8], char *ret_position, uint8_t ret_hardware_version[3], uint8_t ret_firmware_version[3], uint16_t *ret_device_identifier)

 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|
 


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


.. c:function:: void piezo_speaker_register_callback(PiezoSpeaker *piezo_speaker, uint8_t id, void *callback, void *user_data)

 Registers a callback with ID ``id`` to the function ``callback``. The
 ``user_data`` will be given as a parameter of the callback.

 The available IDs with corresponding function signatures are listed
 :ref:`below <piezo_speaker_bricklet_c_callbacks>`.




.. _piezo_speaker_bricklet_c_callbacks:

Callbacks
^^^^^^^^^

Callbacks can be registered to receive
time critical or recurring data from the device. The registration is done
with the :c:func:`piezo_speaker_register_callback` function. The parameters consist of
the device object, the callback ID, the callback function and optional
user data:

 .. code-block:: c

    void my_callback(int p, void *user_data) {
        printf("parameter: %d\n", p);
    }

    piezo_speaker_register_callback(&piezo_speaker, PIEZO_SPEAKER_CALLBACK_EXAMPLE, (void *)my_callback, NULL);

The available constants with corresponding callback function signatures
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.

.. c:var:: PIEZO_SPEAKER_CALLBACK_BEEP_FINISHED

 .. code-block:: c

  void callback(void *user_data)


 This callback is triggered if a beep set by :c:func:`piezo_speaker_beep` is finished
 
.. c:var:: PIEZO_SPEAKER_CALLBACK_MORSE_CODE_FINISHED

 .. code-block:: c

  void callback(void *user_data)


 This callback is triggered if the playback of the morse code set by
 :c:func:`piezo_speaker_morse_code` is finished.
 


.. _piezo_speaker_bricklet_c_constants:

Constants
^^^^^^^^^

.. c:var:: PIEZO_SPEAKER_DEVICE_IDENTIFIER

 This constant is used to identify a Piezo Speaker Bricklet.

 The :c:func:`piezo_speaker_get_identity` function and the :c:data:`IPCON_CALLBACK_ENUMERATE`
 callback of the IP Connection have a ``device_identifier`` parameter to specify
 the Brick's or Bricklet's type.

