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:breadcrumbs: <a href="../../index.html">Home</a> / <a href="../../index.html#software-csharp">Software</a> / C# - Dual Button Bricklet

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

.. _dual_button_bricklet_csharp:

C# - Dual Button Bricklet
=========================

This is the description of the :ref:`C# API bindings <api_bindings_csharp>` for the :ref:`Dual Button Bricklet <dual_button_bricklet>`. General information and technical
specifications for the Dual Button Bricklet are summarized in its :ref:`hardware description
<dual_button_bricklet_description>`.

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

.. _dual_button_bricklet_csharp_examples:


Examples
--------

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

Callback
^^^^^^^^

`Download (ExampleCallback.cs) <https://github.com/Tinkerforge/dual-button-bricklet/raw/master/software/examples/csharp/ExampleCallback.cs>`__

.. literalinclude:: DualButton_Bricklet_CSharp_ExampleCallback.cs
 :language: csharp
 :linenos:
 :tab-width: 4

.. _dual_button_bricklet_csharp_api:

API
---

Generally, every method of the C# bindings that returns a value can
throw a ``Tinkerforge.TimeoutException``. This exception gets thrown if the
device did not respond. If a cable based connection is used, it is
unlikely that this exception gets thrown (assuming nobody plugs the
device out). However, if a wireless connection is used, timeouts will occur
if the distance to the device gets too big.

Since C# does not support multiple return values directly, we use the ``out``
keyword to return multiple values from a method.

The namespace for all Brick/Bricklet bindings and the IPConnection is
``Tinkerforge.*``.

All methods listed below are thread-safe.




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


.. csharp:function:: class BrickletDualButton(String uid, IPConnection ipcon)

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

 .. code-block:: csharp

  BrickletDualButton dualButton = new BrickletDualButton("YOUR_DEVICE_UID", ipcon);

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


.. csharp:function:: public void BrickletDualButton::SetLEDState(byte ledL, byte ledR)

 Sets the state of the LEDs. Possible states are:
 
 * 0 = AutoToggleOn: Enables auto toggle with initially enabled LED.
 * 1 = AutoToggleOff: Activates auto toggle with initially disabled LED.
 * 2 = On: Enables LED (auto toggle is disabled).
 * 3 = Off: Disables LED (auto toggle is disabled).
 
 In auto toggle mode the LED is toggled automatically at each press of a button.
 
 If you just want to set one of the LEDs and don't know the current state
 of the other LED, you can get the state with :csharp:func:`GetLEDState() <BrickletDualButton::GetLEDState>` or you
 can use :csharp:func:`SetSelectedLEDState() <BrickletDualButton::SetSelectedLEDState>`.
 
 The default value is (1, 1).
 
 The following constants are available for this function:
 
 * BrickletDualButton.LED_STATE_AUTO_TOGGLE_ON = 0
 * BrickletDualButton.LED_STATE_AUTO_TOGGLE_OFF = 1
 * BrickletDualButton.LED_STATE_ON = 2
 * BrickletDualButton.LED_STATE_OFF = 3
 
.. csharp:function:: public void BrickletDualButton::GetLEDState(out byte ledL, out byte ledR)

 Returns the current state of the LEDs, as set by :csharp:func:`SetLEDState() <BrickletDualButton::SetLEDState>`.
 
 The following constants are available for this function:
 
 * BrickletDualButton.LED_STATE_AUTO_TOGGLE_ON = 0
 * BrickletDualButton.LED_STATE_AUTO_TOGGLE_OFF = 1
 * BrickletDualButton.LED_STATE_ON = 2
 * BrickletDualButton.LED_STATE_OFF = 3
 
.. csharp:function:: public void BrickletDualButton::GetButtonState(out byte buttonL, out byte buttonR)

 Returns the current state for both buttons. Possible states are:
 
 * 0 = pressed
 * 1 = released
 
 The following constants are available for this function:
 
 * BrickletDualButton.BUTTON_STATE_PRESSED = 0
 * BrickletDualButton.BUTTON_STATE_RELEASED = 1
 


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

.. csharp:function:: public void BrickletDualButton::SetSelectedLEDState(byte led, byte state)

 Sets the state of the selected LED (0 or 1). 
 
 The other LED remains untouched.
 
 The following constants are available for this function:
 
 * BrickletDualButton.LED_LEFT = 0
 * BrickletDualButton.LED_RIGHT = 1
 * BrickletDualButton.LED_STATE_AUTO_TOGGLE_ON = 0
 * BrickletDualButton.LED_STATE_AUTO_TOGGLE_OFF = 1
 * BrickletDualButton.LED_STATE_ON = 2
 * BrickletDualButton.LED_STATE_OFF = 3
 
.. csharp:function:: public byte[] BrickletDualButton::GetAPIVersion()

 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.
 
.. csharp:function:: public bool BrickletDualButton::GetResponseExpected(byte functionId)

 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
 :csharp:func:`SetResponseExpected() <BrickletDualButton::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 :csharp:func:`SetResponseExpected() <BrickletDualButton::SetResponseExpected>`
 for the list of function ID constants available for this function.
 
.. csharp:function:: public void BrickletDualButton::SetResponseExpected(byte functionId, bool responseExpected)

 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:
 
 * BrickletDualButton.FUNCTION_SET_LED_STATE = 1
 * BrickletDualButton.FUNCTION_SET_SELECTED_LED_STATE = 5
 
.. csharp:function:: public void BrickletDualButton::SetResponseExpectedAll(bool responseExpected)

 Changes the response expected flag for all setter and callback configuration
 functions of this device at once.
 
.. csharp:function:: public void BrickletDualButton::GetIdentity(out string uid, out string connectedUid, out char position, out byte[] hardwareVersion, out byte[] firmwareVersion, out int deviceIdentifier)

 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|
 


.. _dual_button_bricklet_csharp_callbacks:

Callbacks
^^^^^^^^^

Callbacks can be registered to receive time critical or recurring data from
the device. The registration is done by appending your callback handler to
the corresponding event:

.. code-block:: csharp

    void Callback(BrickletDualButton sender, int value)
    {
        System.Console.WriteLine("Value: " + value);
    }

    dualButton.ExampleCallback += Callback;

The available events 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.


.. csharp:function:: public event BrickletDualButton::StateChanged(BrickletDualButton sender, byte buttonL, byte buttonR, byte ledL, byte ledR)


  This callback is called whenever a button is pressed. 
  
  Possible states for buttons are:
  
  * 0 = pressed
  * 1 = released
  
  Possible states for LEDs are:
  
  * 0 = AutoToggleOn: Auto toggle enabled and LED on.
  * 1 = AutoToggleOff: Auto toggle enabled and LED off.
  * 2 = On: LED on (auto toggle is disabled).
  * 3 = Off: LED off (auto toggle is disabled).
  
  The following constants are available for this function:
  
  * BrickletDualButton.BUTTON_STATE_PRESSED = 0
  * BrickletDualButton.BUTTON_STATE_RELEASED = 1
  * BrickletDualButton.LED_STATE_AUTO_TOGGLE_ON = 0
  * BrickletDualButton.LED_STATE_AUTO_TOGGLE_OFF = 1
  * BrickletDualButton.LED_STATE_ON = 2
  * BrickletDualButton.LED_STATE_OFF = 3
  


.. _dual_button_bricklet_csharp_constants:

Constants
^^^^^^^^^

.. csharp:member:: public int BrickletDualButton::DEVICE_IDENTIFIER

 This constant is used to identify a Dual Button Bricklet.

 The :csharp:func:`GetIdentity() <BrickletDualButton::GetIdentity>` function and the
 :csharp:func:`EnumerateCallback <IPConnection::EnumerateCallback>`
 callback of the IP Connection have a ``deviceIdentifier`` parameter to specify
 the Brick's or Bricklet's type.

