Mathematica - LCD 20x4 Bricklet

This is the description of the Mathematica API bindings for the LCD 20x4 Bricklet. General information and technical specifications for the LCD 20x4 Bricklet are summarized in its hardware description.

An installation guide for the Mathematica API bindings is part of their general description.

Examples

The example code below is Public Domain (CC0 1.0).

Hello World

Download (ExampleHelloWorld.nb)

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Needs["NETLink`"]
LoadNETAssembly["Tinkerforge",NotebookDirectory[]<>"../../.."]

host="localhost"
port=4223
uid="XYZ"(*Change XYZ to the UID of your LCD 20x4 Bricklet*)

(*Create IPConnection and device object*)
ipcon=NETNew["Tinkerforge.IPConnection"]
lcd=NETNew["Tinkerforge.BrickletLCD20x4",uid,ipcon]
ipcon@Connect[host,port]

(*Turn backlight on*)
lcd@BacklightOn[]

(*Write "Hello World"*)
lcd@WriteLine[0,0,"Hello World"]

(*Clean up*)
ipcon@Disconnect[]
ReleaseNETObject[lcd]
ReleaseNETObject[ipcon]

Button Callback

Download (ExampleButtonCallback.nb)

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Needs["NETLink`"]
LoadNETAssembly["Tinkerforge",NotebookDirectory[]<>"../../.."]

host="localhost"
port=4223
uid="XYZ"(*Change XYZ to the UID of your LCD 20x4 Bricklet*)

(*Create IPConnection and device object*)
ipcon=NETNew["Tinkerforge.IPConnection"]
lcd=NETNew["Tinkerforge.BrickletLCD20x4",uid,ipcon]
ipcon@Connect[host,port]

(*Callback function for button pressed callback*)
ButtonPressedCB[sender_,button_]:=
 Print["Button Pressed: "<>ToString[button]]
AddEventHandler[lcd@ButtonPressedCallback,ButtonPressedCB]

(*Callback function for button released callback*)
ButtonReleasedCB[sender_,button_]:=
 Print["Button Released: "<>ToString[button]]
AddEventHandler[lcd@ButtonReleasedCallback,ButtonReleasedCB]

Input["Click OK to exit"]

(*Clean up*)
ipcon@Disconnect[]
ReleaseNETObject[lcd]
ReleaseNETObject[ipcon]

API

Generally, every method of the Mathematica 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 .NET/Link does not support multiple return values directly, we use the out keyword to return multiple values from a method. For further information about the out keyword in .NET/Link see the corresponding Mathematica .NET/Link documentation.

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

Basic Functions

BrickletLCD20x4[uid, ipcon] → lcd20x4
Parameters:
  • uid -- String
  • ipcon -- NETObject[IPConnection]
Returns:
  • lcd20x4 -- NETObject[BrickletLCD20x4]

Creates an object with the unique device ID uid:

lcd20x4=NETNew["Tinkerforge.BrickletLCD20x4","YOUR_DEVICE_UID",ipcon]

This object can then be used after the IP Connection is connected (see examples above).

The .NET runtime has built-in garbage collection that frees objects that are no longer in use by a program. But because Mathematica can not automatically tell when a Mathematica "program" doesn't use a .NET object anymore, this has to be done by the program. For this the ReleaseNETObject[] function is used in the examples.

For further information about object management in .NET/Link see the corresponding Mathematica .NET/Link documentation.

BrickletLCD20x4@WriteLine[line, position, text] → Null
Parameters:
  • line -- Integer
  • position -- Integer
  • text -- String

Writes text to a specific line (0 to 3) with a specific position (0 to 19). The text can have a maximum of 20 characters.

For example: (0, 7, "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 for details. The Unicode example above shows how to specify non-ASCII characters and how to translate from Unicode to the LCD charset.

BrickletLCD20x4@ClearDisplay[] → Null

Deletes all characters from the display.

BrickletLCD20x4@BacklightOn[] → Null

Turns the backlight on.

BrickletLCD20x4@BacklightOff[] → Null

Turns the backlight off.

BrickletLCD20x4@IsBacklightOn[] → backlight
Returns:
  • backlight -- True/False

Returns true if the backlight is on and false otherwise.

Advanced Functions

BrickletLCD20x4@SetConfig[cursor, blinking] → Null
Parameters:
  • cursor -- True/False
  • blinking -- True/False

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 WriteLine[].

The default is (false, false).

BrickletLCD20x4@GetConfig[out cursor, out blinking] → Null
Parameters:
  • cursor -- True/False
  • blinking -- True/False

Returns the configuration as set by SetConfig[].

BrickletLCD20x4@IsButtonPressed[button] → pressed
Parameters:
  • button -- Integer
Returns:
  • pressed -- True/False

Returns true if the button (0 to 2 or 0 to 3 since hardware version 1.2) is pressed.

If you want to react on button presses and releases it is recommended to use the ButtonPressedCallback and ButtonReleasedCallback callbacks.

BrickletLCD20x4@SetCustomCharacter[index, {character1, character2, ..., character8}] → Null
Parameters:
  • index -- Integer
  • characteri -- Integer

The LCD 20x4 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 WriteLine[] by using the characters with the byte representation 8 ("x08") to 15 ("x0F").

You can play around with the custom characters in Brick Viewer version since 2.0.1.

Custom characters are stored by the LCD in RAM, so they have to be set after each startup.

New in version 2.0.1 (Plugin).

BrickletLCD20x4@GetCustomCharacter[index] → {character1, character2, ..., character8}
Parameters:
  • index -- Integer
Returns:
  • characteri -- Integer

Returns the custom character for a given index, as set with SetCustomCharacter[].

New in version 2.0.1 (Plugin).

BrickletLCD20x4@SetDefaultText[line, text] → Null
Parameters:
  • line -- Integer
  • text -- String

Sets the default text for lines 0-3. The max number of characters per line is 20.

The default text is shown on the LCD, if the default text counter expires, see SetDefaultTextCounter[].

New in version 2.0.2 (Plugin).

BrickletLCD20x4@GetDefaultText[line] → text
Parameters:
  • line -- Integer
Returns:
  • text -- String

Returns the default text for a given line (0-3) as set by SetDefaultText[].

New in version 2.0.2 (Plugin).

BrickletLCD20x4@SetDefaultTextCounter[counter] → Null
Parameters:
  • counter -- Integer

Sets the default text counter in ms. This counter is decremented each ms by the LCD firmware. If the counter reaches 0, the default text (see SetDefaultText[]) is shown on the LCD.

This functionality can be used to show a default text if the controlling program crashes or the connection is interrupted.

A possible approach is to call SetDefaultTextCounter[] every minute with the parameter 1000*60*2 (2 minutes). In this case the default text will be shown no later than 2 minutes after the controlling program crashes.

A negative counter turns the default text functionality off.

The default is -1.

New in version 2.0.2 (Plugin).

BrickletLCD20x4@GetDefaultTextCounter[] → counter
Returns:
  • counter -- Integer

Returns the current value of the default text counter.

New in version 2.0.2 (Plugin).

BrickletLCD20x4@GetAPIVersion[] → {apiVersion1, apiVersion2, apiVersion3}
Returns:
  • apiVersioni -- Integer

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.

BrickletLCD20x4@GetResponseExpected[functionId] → responseExpected
Parameters:
  • functionId -- Integer
Returns:
  • responseExpected -- True/False

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 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 SetResponseExpected[] for the list of function ID constants available for this function.

BrickletLCD20x4@SetResponseExpected[functionId, responseExpected] → Null
Parameters:
  • functionId -- Integer
  • responseExpected -- True/False

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.

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:

  • BrickletLCD20x4`FUNCTIONUWRITEULINE = 1
  • BrickletLCD20x4`FUNCTIONUCLEARUDISPLAY = 2
  • BrickletLCD20x4`FUNCTIONUBACKLIGHTUON = 3
  • BrickletLCD20x4`FUNCTIONUBACKLIGHTUOFF = 4
  • BrickletLCD20x4`FUNCTIONUSETUCONFIG = 6
  • BrickletLCD20x4`FUNCTIONUSETUCUSTOMUCHARACTER = 11
  • BrickletLCD20x4`FUNCTIONUSETUDEFAULTUTEXT = 13
  • BrickletLCD20x4`FUNCTIONUSETUDEFAULTUTEXTUCOUNTER = 15
BrickletLCD20x4@SetResponseExpectedAll[responseExpected] → Null
Parameters:
  • responseExpected -- True/False

Changes the response expected flag for all setter and callback configuration functions of this device at once.

BrickletLCD20x4@GetIdentity[out uid, out connectedUid, out position, out {hardwareVersion1, hardwareVersion2, hardwareVersion3}, out {firmwareVersion1, firmwareVersion2, firmwareVersion3}, out deviceIdentifier] → Null
Parameters:
  • uid -- String
  • connectedUid -- String
  • position -- Integer
  • hardwareVersioni -- Integer
  • firmwareVersioni -- Integer
  • deviceIdentifier -- 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 here. There is also a constant for the device identifier of this Bricklet.

Callbacks

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

MyCallback[sender_,value_]:=Print["Value: "<>ToString[value]]

AddEventHandler[lcd20x4@ExampleCallback,MyCallback]

For further information about event handling using .NET/Link see the corresponding Mathematica .NET/Link documentation.

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.

event BrickletLCD20x4@ButtonPressedCallback[sender, button]
Parameters:
  • sender -- NETObject[BrickletLCD20x4]
  • button -- Integer

This callback is triggered when a button is pressed. The parameter is the number of the button (0 to 2 or 0 to 3 since hardware version 1.2).

event BrickletLCD20x4@ButtonReleasedCallback[sender, button]
Parameters:
  • sender -- NETObject[BrickletLCD20x4]
  • button -- Integer

This callback is triggered when a button is released. The parameter is the number of the button (0 to 2 or 0 to 3 since hardware version 1.2).

Constants

BrickletLCD20x4`DEVICEUIDENTIFIER

This constant is used to identify a LCD 20x4 Bricklet.

The GetIdentity[] function and the EnumerateCallback callback of the IP Connection have a deviceIdentifier parameter to specify the Brick's or Bricklet's type.

BrickletLCD20x4`DEVICEDISPLAYNAME

This constant represents the human readable name of a LCD 20x4 Bricklet.