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:breadcrumbs: <a href="../../index.html">Home</a> / <a href="../../index.html#software-vbnet">Software</a> / Visual Basic .NET - LCD 16x2 Bricklet

.. |device_identifier_constant| replace:: There is also a :ref:`constant <lcd_16x2_bricklet_vbnet_constants>` for the device identifier of this Bricklet.

.. _lcd_16x2_bricklet_vbnet:

Visual Basic .NET - LCD 16x2 Bricklet
=====================================

This is the description of the :ref:`Visual Basic .NET API bindings <api_bindings_vbnet>` for the :ref:`LCD 16x2 Bricklet <lcd_16x2_bricklet>`. General information and technical
specifications for the LCD 16x2 Bricklet are summarized in its :ref:`hardware description
<lcd_16x2_bricklet_description>`.

An :ref:`installation guide <api_bindings_vbnet_install>` for the Visual Basic .NET API
bindings is part of their general description.

.. _lcd_16x2_bricklet_vbnet_examples:


Examples
--------

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

Hello World
^^^^^^^^^^^

`Download (ExampleHelloWorld.vb) <https://github.com/Tinkerforge/lcd-16x2-bricklet/raw/master/software/examples/vbnet/ExampleHelloWorld.vb>`__

.. literalinclude:: LCD16x2_Bricklet_VBNET_ExampleHelloWorld.vb
 :language: vbnet
 :linenos:
 :tab-width: 4

Button Callback
^^^^^^^^^^^^^^^

`Download (ExampleButtonCallback.vb) <https://github.com/Tinkerforge/lcd-16x2-bricklet/raw/master/software/examples/vbnet/ExampleButtonCallback.vb>`__

.. literalinclude:: LCD16x2_Bricklet_VBNET_ExampleButtonCallback.vb
 :language: vbnet
 :linenos:
 :tab-width: 4

Unicode
^^^^^^^

`Download (ExampleUnicode.vb) <https://github.com/Tinkerforge/lcd-16x2-bricklet/raw/master/software/examples/vbnet/ExampleUnicode.vb>`__

.. literalinclude:: LCD16x2_Bricklet_VBNET_ExampleUnicode.vb
 :language: vbnet
 :linenos:
 :tab-width: 4

.. _lcd_16x2_bricklet_vbnet_api:

API
---

Since Visual Basic .NET does not support multiple return values directly, we
use the ``ByRef`` keyword to return multiple values from a function.

All functions and procedures listed below are thread-safe.




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


.. vbnet:function:: Class BrickletLCD16x2(ByVal uid As String, ByVal ipcon As IPConnection)

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

 .. code-block:: vbnet

    Dim lcd16x2 As New BrickletLCD16x2("YOUR_DEVICE_UID", ipcon)

 This object can then be used after the IP Connection is connected
 (see examples :ref:`above <lcd_16x2_bricklet_vbnet_examples>`).


.. vbnet:function:: Sub BrickletLCD16x2.WriteLine(ByVal line As Byte, ByVal position As Byte, ByVal text As String)

 Writes text to a specific line (0 to 1) with a specific position 
 (0 to 15). The text can have a maximum of 16 characters.
 
 For example: (0, 5, "Hello") will write *Hello* in the middle of the
 first line of the display.
 
 The display uses a special charset that includes all ASCII characters except
 backslash and tilde. The LCD charset also includes several other non-ASCII characters, see
 the `charset specification <https://github.com/Tinkerforge/lcd-16x2-bricklet/raw/master/datasheets/standard_charset.pdf>`__
 for details. The Unicode example above shows how to specify non-ASCII characters
 and how to translate from Unicode to the LCD charset.
 
.. vbnet:function:: Sub BrickletLCD16x2.ClearDisplay()

 Deletes all characters from the display.
 
.. vbnet:function:: Sub BrickletLCD16x2.BacklightOn()

 Turns the backlight on.
 
.. vbnet:function:: Sub BrickletLCD16x2.BacklightOff()

 Turns the backlight off.
 
.. vbnet:function:: Function BrickletLCD16x2.IsBacklightOn() As Boolean

 Returns *true* if the backlight is on and *false* otherwise.
 


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

.. vbnet:function:: Sub BrickletLCD16x2.SetConfig(ByVal cursor As Boolean, ByVal blinking As Boolean)

 Configures if the cursor (shown as "_") should be visible and if it
 should be blinking (shown as a blinking block). The cursor position
 is one character behind the the last text written with 
 :vbnet:func:`WriteLine() <BrickletLCD16x2.WriteLine>`.
 
 The default is (false, false).
 
.. vbnet:function:: Sub BrickletLCD16x2.GetConfig(ByRef cursor As Boolean, ByRef blinking As Boolean)

 Returns the configuration as set by :vbnet:func:`SetConfig() <BrickletLCD16x2.SetConfig>`.
 
.. vbnet:function:: Function BrickletLCD16x2.IsButtonPressed(ByVal button As Byte) As Boolean

 Returns *true* if the button (0 to 2) is pressed. If you want to react
 on button presses and releases it is recommended to use the
 :vbnet:func:`ButtonPressed <BrickletLCD16x2.ButtonPressed>` and :vbnet:func:`ButtonReleased <BrickletLCD16x2.ButtonReleased>` callbacks.
 
.. vbnet:function:: Sub BrickletLCD16x2.SetCustomCharacter(ByVal index As Byte, ByVal character[] As Byte)

 The LCD 16x2 Bricklet can store up to 8 custom characters. The characters
 consist of 5x8 pixels and can be addressed with the index 0-7. To describe
 the pixels, the first 5 bits of 8 bytes are used. For example, to make
 a custom character "H", you should transfer the following:
 
 * ``character[0] = 0b00010001`` (decimal value 17)
 * ``character[1] = 0b00010001`` (decimal value 17)
 * ``character[2] = 0b00010001`` (decimal value 17)
 * ``character[3] = 0b00011111`` (decimal value 31)
 * ``character[4] = 0b00010001`` (decimal value 17)
 * ``character[5] = 0b00010001`` (decimal value 17)
 * ``character[6] = 0b00010001`` (decimal value 17)
 * ``character[7] = 0b00000000`` (decimal value 0)
 
 The characters can later be written with :vbnet:func:`WriteLine() <BrickletLCD16x2.WriteLine>` by using the
 characters with the byte representation 8 to 15.
 
 You can play around with the custom characters in Brick Viewer since
 version 2.0.1.
 
 Custom characters are stored by the LCD in RAM, so they have to be set
 after each startup.
 
 .. versionadded:: 2.0.1~(Plugin)
 
.. vbnet:function:: Function BrickletLCD16x2.GetCustomCharacter(ByVal index As Byte) As Byte[]

 Returns the custom character for a given index, as set with
 :vbnet:func:`SetCustomCharacter() <BrickletLCD16x2.SetCustomCharacter>`.
 
 .. versionadded:: 2.0.1~(Plugin)
 
.. vbnet:function:: Function BrickletLCD16x2.GetAPIVersion() As 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.
 
.. vbnet:function:: Function BrickletLCD16x2.GetResponseExpected(ByVal functionId As Byte) As 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
 :vbnet:func:`SetResponseExpected() <BrickletLCD16x2.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 :vbnet:func:`SetResponseExpected() <BrickletLCD16x2.SetResponseExpected>`
 for the list of function ID constants available for this function.
 
.. vbnet:function:: Sub BrickletLCD16x2.SetResponseExpected(ByVal functionId As Byte, ByVal responseExpected As 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:
 
 * BrickletLCD16x2.FUNCTION_WRITE_LINE = 1
 * BrickletLCD16x2.FUNCTION_CLEAR_DISPLAY = 2
 * BrickletLCD16x2.FUNCTION_BACKLIGHT_ON = 3
 * BrickletLCD16x2.FUNCTION_BACKLIGHT_OFF = 4
 * BrickletLCD16x2.FUNCTION_SET_CONFIG = 6
 * BrickletLCD16x2.FUNCTION_SET_CUSTOM_CHARACTER = 11
 
.. vbnet:function:: Sub BrickletLCD16x2.SetResponseExpectedAll(ByVal responseExpected As Boolean)

 Changes the response expected flag for all setter and callback configuration
 functions of this device at once.
 
.. vbnet:function:: Sub BrickletLCD16x2.GetIdentity(ByRef uid As String, ByRef connectedUid As String, ByRef position As Char, ByRef hardwareVersion[] As Byte, ByRef firmwareVersion[] As Byte, ByRef deviceIdentifier As Integer)

 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|
 


.. _lcd_16x2_bricklet_vbnet_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:: vbnet

    Sub Callback(ByVal sender As BrickletLCD16x2, ByVal value As Short)
        Console.WriteLine("Value: {0}", value)
    End Sub

    AddHandler lcd16x2.Example, AddressOf Callback

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.


.. vbnet:function:: Event BrickletLCD16x2.ButtonPressed(ByVal sender As BrickletLCD16x2, ByVal button As Byte)


 This callback is triggered when a button is pressed. The parameter is
 the number of the button (0 to 2).
 

.. vbnet:function:: Event BrickletLCD16x2.ButtonReleased(ByVal sender As BrickletLCD16x2, ByVal button As Byte)


 This callback is triggered when a button is released. The parameter is
 the number of the button (0 to 2).
 


.. _lcd_16x2_bricklet_vbnet_constants:

Constants
^^^^^^^^^

.. vbnet:attribute:: Const BrickletLCD16x2.DEVICE_IDENTIFIER

 This constant is used to identify a LCD 16x2 Bricklet.

 The :vbnet:func:`GetIdentity() <BrickletLCD16x2.GetIdentity>` function and the
 :vbnet:func:`EnumerateCallback <IPConnection.EnumerateCallback>`
 callback of the IP Connection have a ``deviceIdentifier`` parameter to specify
 the Brick's or Bricklet's type.

