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

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

.. _ptc_bricklet_c:

C/C++ - PTC Bricklet
====================

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

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

.. _ptc_bricklet_c_examples:


Examples
--------

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

Simple
^^^^^^

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

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

Callback
^^^^^^^^

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

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

Threshold
^^^^^^^^^

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

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

.. _ptc_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 ptc_create(PTC *ptc, const char *uid, IPConnection *ipcon)

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

 .. code-block:: c

    PTC ptc;
    ptc_create(&ptc, "YOUR_DEVICE_UID", &ipcon);

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

.. c:function:: void ptc_destroy(PTC *ptc)

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


.. c:function:: int ptc_get_temperature(PTC *ptc, int32_t *ret_temperature)

 Returns the temperature of connected sensor. The value
 has a range of -246 to 849 °C and is given in °C/100,
 e.g. a value of 4223 means that a temperature of 42.23 °C is measured.
 
 If you want to get the temperature periodically, it is recommended 
 to use the callback :c:data:`PTC_CALLBACK_TEMPERATURE` and set the period with 
 :c:func:`ptc_set_temperature_callback_period`.
 
.. c:function:: int ptc_is_sensor_connected(PTC *ptc, bool *ret_connected)

 Returns *true* if the sensor is connected correctly. 
 
 If this function
 returns *false*, there is either no Pt100 or Pt1000 sensor connected,
 the sensor is connected incorrectly or the sensor itself is faulty.
 
.. c:function:: int ptc_set_wire_mode(PTC *ptc, uint8_t mode)

 Sets the wire mode of the sensor. Possible values are 2, 3 and 4 which
 correspond to 2-, 3- and 4-wire sensors. The value has to match the jumper
 configuration on the Bricklet.
 
 The default value is 2 = 2-wire.
 
 The following defines are available for this function:
 
 * PTC_WIRE_MODE_2 = 2
 * PTC_WIRE_MODE_3 = 3
 * PTC_WIRE_MODE_4 = 4
 
.. c:function:: int ptc_get_wire_mode(PTC *ptc, uint8_t *ret_mode)

 Returns the wire mode as set by :c:func:`ptc_set_wire_mode`
 
 The following defines are available for this function:
 
 * PTC_WIRE_MODE_2 = 2
 * PTC_WIRE_MODE_3 = 3
 * PTC_WIRE_MODE_4 = 4
 


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

.. c:function:: int ptc_get_resistance(PTC *ptc, uint16_t *ret_resistance)

 Returns the value as measured by the MAX31865 precision delta-sigma ADC.
 
 The value can be converted with the following formulas:
 
 * Pt100:  resistance = (value * 390) / 32768
 * Pt1000: resistance = (value * 3900) / 32768
 
 If you want to get the resistance periodically, it is recommended 
 to use the callback :c:data:`PTC_CALLBACK_RESISTANCE` and set the period with 
 :c:func:`ptc_set_resistance_callback_period`.
 
.. c:function:: int ptc_set_noise_rejection_filter(PTC *ptc, uint8_t filter)

 Sets the noise rejection filter to either 50Hz (0) or 60Hz (1).
 Noise from 50Hz or 60Hz power sources (including
 harmonics of the AC power's fundamental frequency) is
 attenuated by 82dB.
 
 Default value is 0 = 50Hz.
 
 The following defines are available for this function:
 
 * PTC_FILTER_OPTION_50HZ = 0
 * PTC_FILTER_OPTION_60HZ = 1
 
.. c:function:: int ptc_get_noise_rejection_filter(PTC *ptc, uint8_t *ret_filter)

 Returns the noise rejection filter option as set by 
 :c:func:`ptc_set_noise_rejection_filter`
 
 The following defines are available for this function:
 
 * PTC_FILTER_OPTION_50HZ = 0
 * PTC_FILTER_OPTION_60HZ = 1
 
.. c:function:: int ptc_get_api_version(PTC *ptc, 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 ptc_get_response_expected(PTC *ptc, 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:`ptc_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:`ptc_set_response_expected`
 for the list of function ID defines available for this function.
 
.. c:function:: int ptc_set_response_expected(PTC *ptc, 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:
 
 * PTC_FUNCTION_SET_TEMPERATURE_CALLBACK_PERIOD = 3
 * PTC_FUNCTION_SET_RESISTANCE_CALLBACK_PERIOD = 5
 * PTC_FUNCTION_SET_TEMPERATURE_CALLBACK_THRESHOLD = 7
 * PTC_FUNCTION_SET_RESISTANCE_CALLBACK_THRESHOLD = 9
 * PTC_FUNCTION_SET_DEBOUNCE_PERIOD = 11
 * PTC_FUNCTION_SET_NOISE_REJECTION_FILTER = 17
 * PTC_FUNCTION_SET_WIRE_MODE = 20
 
.. c:function:: int ptc_set_response_expected_all(PTC *ptc, bool response_expected)

 Changes the response expected flag for all setter and callback configuration
 functions of this device at once.
 
.. c:function:: int ptc_get_identity(PTC *ptc, 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 ptc_register_callback(PTC *ptc, 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 <ptc_bricklet_c_callbacks>`.


.. c:function:: int ptc_set_temperature_callback_period(PTC *ptc, uint32_t period)

 Sets the period in ms with which the :c:data:`PTC_CALLBACK_TEMPERATURE` callback is triggered
 periodically. A value of 0 turns the callback off.
 
 :c:data:`PTC_CALLBACK_TEMPERATURE` is only triggered if the temperature has changed since the
 last triggering.
 
 The default value is 0.
 
.. c:function:: int ptc_get_temperature_callback_period(PTC *ptc, uint32_t *ret_period)

 Returns the period as set by :c:func:`ptc_set_temperature_callback_period`.
 
.. c:function:: int ptc_set_resistance_callback_period(PTC *ptc, uint32_t period)

 Sets the period in ms with which the :c:data:`PTC_CALLBACK_RESISTANCE` callback is triggered
 periodically. A value of 0 turns the callback off.
 
 :c:data:`PTC_CALLBACK_RESISTANCE` is only triggered if the resistance has changed since the
 last triggering.
 
 The default value is 0.
 
.. c:function:: int ptc_get_resistance_callback_period(PTC *ptc, uint32_t *ret_period)

 Returns the period as set by :c:func:`ptc_set_resistance_callback_period`.
 
.. c:function:: int ptc_set_temperature_callback_threshold(PTC *ptc, char option, int32_t min, int32_t max)

 Sets the thresholds for the :c:data:`PTC_CALLBACK_TEMPERATURE_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 temperature is *outside* the min and max values"
  "'i'",    "Callback is triggered when the temperature is *inside* the min and max values"
  "'<'",    "Callback is triggered when the temperature is smaller than the min value (max is ignored)"
  "'>'",    "Callback is triggered when the temperature is greater than the min value (max is ignored)"
 
 The default value is ('x', 0, 0).
 
 The following defines are available for this function:
 
 * PTC_THRESHOLD_OPTION_OFF = 'x'
 * PTC_THRESHOLD_OPTION_OUTSIDE = 'o'
 * PTC_THRESHOLD_OPTION_INSIDE = 'i'
 * PTC_THRESHOLD_OPTION_SMALLER = '<'
 * PTC_THRESHOLD_OPTION_GREATER = '>'
 
.. c:function:: int ptc_get_temperature_callback_threshold(PTC *ptc, char *ret_option, int32_t *ret_min, int32_t *ret_max)

 Returns the threshold as set by :c:func:`ptc_set_temperature_callback_threshold`.
 
 The following defines are available for this function:
 
 * PTC_THRESHOLD_OPTION_OFF = 'x'
 * PTC_THRESHOLD_OPTION_OUTSIDE = 'o'
 * PTC_THRESHOLD_OPTION_INSIDE = 'i'
 * PTC_THRESHOLD_OPTION_SMALLER = '<'
 * PTC_THRESHOLD_OPTION_GREATER = '>'
 
.. c:function:: int ptc_set_resistance_callback_threshold(PTC *ptc, char option, uint16_t min, uint16_t max)

 Sets the thresholds for the :c:data:`PTC_CALLBACK_RESISTANCE_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 temperature is *outside* the min and max values"
  "'i'",    "Callback is triggered when the temperature is *inside* the min and max values"
  "'<'",    "Callback is triggered when the temperature is smaller than the min value (max is ignored)"
  "'>'",    "Callback is triggered when the temperature is greater than the min value (max is ignored)"
 
 The default value is ('x', 0, 0).
 
 The following defines are available for this function:
 
 * PTC_THRESHOLD_OPTION_OFF = 'x'
 * PTC_THRESHOLD_OPTION_OUTSIDE = 'o'
 * PTC_THRESHOLD_OPTION_INSIDE = 'i'
 * PTC_THRESHOLD_OPTION_SMALLER = '<'
 * PTC_THRESHOLD_OPTION_GREATER = '>'
 
.. c:function:: int ptc_get_resistance_callback_threshold(PTC *ptc, char *ret_option, uint16_t *ret_min, uint16_t *ret_max)

 Returns the threshold as set by :c:func:`ptc_set_resistance_callback_threshold`.
 
 The following defines are available for this function:
 
 * PTC_THRESHOLD_OPTION_OFF = 'x'
 * PTC_THRESHOLD_OPTION_OUTSIDE = 'o'
 * PTC_THRESHOLD_OPTION_INSIDE = 'i'
 * PTC_THRESHOLD_OPTION_SMALLER = '<'
 * PTC_THRESHOLD_OPTION_GREATER = '>'
 
.. c:function:: int ptc_set_debounce_period(PTC *ptc, uint32_t debounce)

 Sets the period in ms with which the threshold callback
 
 * :c:data:`PTC_CALLBACK_TEMPERATURE_REACHED`,
 * :c:data:`PTC_CALLBACK_RESISTANCE_REACHED`
 
 is triggered, if the threshold
 
 * :c:func:`ptc_set_temperature_callback_threshold`,
 * :c:func:`ptc_set_resistance_callback_threshold`
 
 keeps being reached.
 
 The default value is 100.
 
.. c:function:: int ptc_get_debounce_period(PTC *ptc, uint32_t *ret_debounce)

 Returns the debounce period as set by :c:func:`ptc_set_debounce_period`.
 


.. _ptc_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:`ptc_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);
    }

    ptc_register_callback(&ptc, PTC_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:: PTC_CALLBACK_TEMPERATURE

 .. code-block:: c

  void callback(int32_t temperature, void *user_data)


 This callback is triggered periodically with the period that is set by
 :c:func:`ptc_set_temperature_callback_period`. The parameter is the temperature
 of the connected sensor.
 
 :c:data:`PTC_CALLBACK_TEMPERATURE` is only triggered if the temperature has changed since the
 last triggering.
 
.. c:var:: PTC_CALLBACK_TEMPERATURE_REACHED

 .. code-block:: c

  void callback(int32_t temperature, void *user_data)


 This callback is triggered when the threshold as set by
 :c:func:`ptc_set_temperature_callback_threshold` is reached.
 The parameter is the temperature of the connected sensor.
 
 If the threshold keeps being reached, the callback is triggered periodically
 with the period as set by :c:func:`ptc_set_debounce_period`.
 
.. c:var:: PTC_CALLBACK_RESISTANCE

 .. code-block:: c

  void callback(uint16_t resistance, void *user_data)


 This callback is triggered periodically with the period that is set by
 :c:func:`ptc_set_resistance_callback_period`. The parameter is the resistance
 of the connected sensor.
 
 :c:data:`PTC_CALLBACK_RESISTANCE` is only triggered if the resistance has changed since the
 last triggering.
 
.. c:var:: PTC_CALLBACK_RESISTANCE_REACHED

 .. code-block:: c

  void callback(uint16_t resistance, void *user_data)


 This callback is triggered when the threshold as set by
 :c:func:`ptc_set_resistance_callback_threshold` is reached.
 The parameter is the resistance of the connected sensor.
 
 If the threshold keeps being reached, the callback is triggered periodically
 with the period as set by :c:func:`ptc_set_debounce_period`.
 


.. _ptc_bricklet_c_constants:

Constants
^^^^^^^^^

.. c:var:: PTC_DEVICE_IDENTIFIER

 This constant is used to identify a PTC Bricklet.

 The :c:func:`ptc_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.

