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:breadcrumbs: <a href="../../index.html">Home</a> / <a href="../../index.html#software-delphi">Software</a> / Delphi/Lazarus - CO2 Bricklet

.. |device_identifier_constant| replace:: There is also a :ref:`constant <co2_bricklet_delphi_constants>` for the device identifier of this Bricklet.

.. _co2_bricklet_delphi:

Delphi/Lazarus - CO2 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:`Delphi/Lazarus API bindings <api_bindings_delphi>` for the :ref:`CO2 Bricklet <co2_bricklet>`. General information and technical
specifications for the CO2 Bricklet are summarized in its :ref:`hardware description
<co2_bricklet_description>`.

An :ref:`installation guide <api_bindings_delphi_install>` for the Delphi/Lazarus API
bindings is part of their general description.

.. _co2_bricklet_delphi_examples:


Examples
--------

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

.. _co2_bricklet_delphi_api:

API
---

Since Delphi does not support multiple return values directly, we use the
``out`` keyword to return multiple values from a function.

All functions and procedures listed below are thread-safe.




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


.. delphi:function:: constructor TBrickletCO2.Create(const uid: string; ipcon: TIPConnection)

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

 .. code-block:: delphi

    co2 := TBrickletCO2.Create('YOUR_DEVICE_UID', ipcon);

 This object can then be used after the IP Connection is connected
 (see examples :ref:`above <co2_bricklet_delphi_examples>`).


.. delphi:function:: function TBrickletCO2.GetCO2Concentration(): word

 Returns the measured CO2 concentration. The value is in ppb and
 between TBD and TBD.
 
 If you want to get the CO2 concentration periodically, it is recommended to use the
 callback :delphi:func:`OnCO2Concentration <TBrickletCO2.OnCO2Concentration>` and set the period with
 :delphi:func:`SetCO2ConcentrationCallbackPeriod <TBrickletCO2.SetCO2ConcentrationCallbackPeriod>`.
 


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

.. delphi:function:: function TBrickletCO2.GetAPIVersion(): array [0..2] of byte

 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.
 
.. delphi:function:: function TBrickletCO2.GetResponseExpected(const functionId: byte): boolean

 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
 :delphi:func:`SetResponseExpected <TBrickletCO2.SetResponseExpected>`. 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 :delphi:func:`SetResponseExpected <TBrickletCO2.SetResponseExpected>`
 for the list of function ID constants available for this function.
 
.. delphi:function:: procedure TBrickletCO2.SetResponseExpected(const functionId: byte; const responseExpected: boolean)

 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:
 
 * BRICKLET_CO2_FUNCTION_SET_CO2_CONCENTRATION_CALLBACK_PERIOD = 2
 * BRICKLET_CO2_FUNCTION_SET_CO2_CONCENTRATION_CALLBACK_THRESHOLD = 4
 * BRICKLET_CO2_FUNCTION_SET_DEBOUNCE_PERIOD = 6
 
.. delphi:function:: procedure TBrickletCO2.SetResponseExpectedAll(const responseExpected: boolean)

 Changes the response expected flag for all setter and callback configuration
 functions of this device at once.
 
.. delphi:function:: procedure TBrickletCO2.GetIdentity(out uid: string; out connectedUid: string; out position: char; out hardwareVersion: array [0..2] of byte; out firmwareVersion: array [0..2] of byte; out deviceIdentifier: word)

 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
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

.. delphi:function:: procedure TBrickletCO2.SetCO2ConcentrationCallbackPeriod(const period: longword)

 Sets the period in ms with which the :delphi:func:`OnCO2Concentration <TBrickletCO2.OnCO2Concentration>` callback is triggered
 periodically. A value of 0 turns the callback off.
 
 :delphi:func:`OnCO2Concentration <TBrickletCO2.OnCO2Concentration>` is only triggered if the co2_concentration has changed since the
 last triggering.
 
 The default value is 0.
 
.. delphi:function:: function TBrickletCO2.GetCO2ConcentrationCallbackPeriod(): longword

 Returns the period as set by :delphi:func:`SetCO2ConcentrationCallbackPeriod <TBrickletCO2.SetCO2ConcentrationCallbackPeriod>`.
 
.. delphi:function:: procedure TBrickletCO2.SetCO2ConcentrationCallbackThreshold(const option: char; const min: smallint; const max: smallint)

 Sets the thresholds for the :delphi:func:`OnCO2ConcentrationReached <TBrickletCO2.OnCO2ConcentrationReached>` 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 co2_concentration is *outside* the min and max values"
  "'i'",    "Callback is triggered when the co2_concentration is *inside* the min and max values"
  "'<'",    "Callback is triggered when the co2_concentration is smaller than the min value (max is ignored)"
  "'>'",    "Callback is triggered when the co2_concentration is greater than the min value (max is ignored)"
 
 The default value is ('x', 0, 0).
 
 The following constants are available for this function:
 
 * BRICKLET_CO2_THRESHOLD_OPTION_OFF = 'x'
 * BRICKLET_CO2_THRESHOLD_OPTION_OUTSIDE = 'o'
 * BRICKLET_CO2_THRESHOLD_OPTION_INSIDE = 'i'
 * BRICKLET_CO2_THRESHOLD_OPTION_SMALLER = '<'
 * BRICKLET_CO2_THRESHOLD_OPTION_GREATER = '>'
 
.. delphi:function:: procedure TBrickletCO2.GetCO2ConcentrationCallbackThreshold(out option: char; out min: smallint; out max: smallint)

 Returns the threshold as set by :delphi:func:`SetCO2ConcentrationCallbackThreshold <TBrickletCO2.SetCO2ConcentrationCallbackThreshold>`.
 
 The following constants are available for this function:
 
 * BRICKLET_CO2_THRESHOLD_OPTION_OFF = 'x'
 * BRICKLET_CO2_THRESHOLD_OPTION_OUTSIDE = 'o'
 * BRICKLET_CO2_THRESHOLD_OPTION_INSIDE = 'i'
 * BRICKLET_CO2_THRESHOLD_OPTION_SMALLER = '<'
 * BRICKLET_CO2_THRESHOLD_OPTION_GREATER = '>'
 
.. delphi:function:: procedure TBrickletCO2.SetDebouncePeriod(const debounce: longword)

 Sets the period in ms with which the threshold callbacks
 
 * :delphi:func:`OnCO2ConcentrationReached <TBrickletCO2.OnCO2ConcentrationReached>`,
 
 are triggered, if the thresholds
 
 * :delphi:func:`SetCO2ConcentrationCallbackThreshold <TBrickletCO2.SetCO2ConcentrationCallbackThreshold>`,
 
 keep being reached.
 
 The default value is 100.
 
.. delphi:function:: function TBrickletCO2.GetDebouncePeriod(): longword

 Returns the debounce period as set by :delphi:func:`SetDebouncePeriod <TBrickletCO2.SetDebouncePeriod>`.
 




.. _co2_bricklet_delphi_callbacks:

Callbacks
^^^^^^^^^

Callbacks can be registered to receive time critical or recurring data from
the device. The registration is done by assigning a procedure to an callback
property of the device object:

 .. code-block:: delphi

  procedure TExample.MyCallback(sender: TBrickletCO2; const param: word);
  begin
    WriteLn(param);
  end;

  co2.OnExample := {$ifdef FPC}@{$endif}example.MyCallback;

The available callback property and their 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.

.. delphi:function:: property TBrickletCO2.OnCO2Concentration

 .. code-block:: delphi

  procedure(sender: TBrickletCO2; const co2Concentration: word) of object;


 This callback is triggered periodically with the period that is set by
 :delphi:func:`SetCO2ConcentrationCallbackPeriod <TBrickletCO2.SetCO2ConcentrationCallbackPeriod>`. The parameter is the co2 concentration of the
 sensor.
 
 :delphi:func:`OnCO2Concentration <TBrickletCO2.OnCO2Concentration>` is only triggered if the co2 concentration has changed since the
 last triggering.
 
.. delphi:function:: property TBrickletCO2.OnCO2ConcentrationReached

 .. code-block:: delphi

  procedure(sender: TBrickletCO2; const co2Concentration: word) of object;


 This callback is triggered when the threshold as set by
 :delphi:func:`SetCO2ConcentrationCallbackThreshold <TBrickletCO2.SetCO2ConcentrationCallbackThreshold>` is reached.
 The parameter is the CO2 concentration.
 
 If the threshold keeps being reached, the callback is triggered periodically
 with the period as set by :delphi:func:`SetDebouncePeriod <TBrickletCO2.SetDebouncePeriod>`.
 


.. _co2_bricklet_delphi_constants:

Constants
^^^^^^^^^

.. delphi:function:: const BRICKLET_CO2_DEVICE_IDENTIFIER

 This constant is used to identify a CO2 Bricklet.

 The :delphi:func:`GetIdentity <TBrickletCO2.GetIdentity>` function and the
 :delphi:func:`OnEnumerate <TIPConnection.OnEnumerate>`
 callback of the IP Connection have a ``deviceIdentifier`` parameter to specify
 the Brick's or Bricklet's type.

