Delphi/Lazarus - LCD 16x2 Bricklet

This is the description of the Delphi/Lazarus API bindings for the LCD 16x2 Bricklet. General information and technical specifications for the LCD 16x2 Bricklet are summarized in its hardware description.

An installation guide for the Delphi/Lazarus API bindings is part of their general description.

Examples

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

Hello World

Download (ExampleHelloWorld.pas)

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
program ExampleHelloWorld;

{$ifdef MSWINDOWS}{$apptype CONSOLE}{$endif}
{$ifdef FPC}{$mode OBJFPC}{$H+}{$endif}

uses
  SysUtils, IPConnection, BrickletLCD16x2;

type
  TExample = class
  private
    ipcon: TIPConnection;
    lcd: TBrickletLCD16x2;
  public
    procedure Execute;
  end;

const
  HOST = 'localhost';
  PORT = 4223;
  UID = 'XYZ'; { Change XYZ to the UID of your LCD 16x2 Bricklet }

var
  e: TExample;

procedure TExample.Execute;
begin
  { Create IP connection }
  ipcon := TIPConnection.Create;

  { Create device object }
  lcd := TBrickletLCD16x2.Create(UID, ipcon);

  { Connect to brickd }
  ipcon.Connect(HOST, PORT);
  { Don't use device before ipcon is connected }

  { Turn backlight on }
  lcd.BacklightOn;

  { Write "Hello World" }
  lcd.WriteLine(0, 0, 'Hello World');

  WriteLn('Press key to exit');
  ReadLn;
  ipcon.Destroy; { Calls ipcon.Disconnect internally }
end;

begin
  e := TExample.Create;
  e.Execute;
  e.Destroy;
end.

Button Callback

Download (ExampleButtonCallback.pas)

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
program ExampleButtonCallback;

{$ifdef MSWINDOWS}{$apptype CONSOLE}{$endif}
{$ifdef FPC}{$mode OBJFPC}{$H+}{$endif}

uses
  SysUtils, IPConnection, BrickletLCD16x2;

type
  TExample = class
  private
    ipcon: TIPConnection;
    lcd: TBrickletLCD16x2;
  public
    procedure ButtonPressedCB(sender: TBrickletLCD16x2; const button: byte);
    procedure ButtonReleasedCB(sender: TBrickletLCD16x2; const button: byte);
    procedure Execute;
  end;

const
  HOST = 'localhost';
  PORT = 4223;
  UID = 'XYZ'; { Change XYZ to the UID of your LCD 16x2 Bricklet }

var
  e: TExample;

{ Callback procedure for button pressed callback }
procedure TExample.ButtonPressedCB(sender: TBrickletLCD16x2; const button: byte);
begin
  WriteLn(Format('Button Pressed: %d', [button]));
end;

{ Callback procedure for button released callback }
procedure TExample.ButtonReleasedCB(sender: TBrickletLCD16x2; const button: byte);
begin
  WriteLn(Format('Button Released: %d', [button]));
end;

procedure TExample.Execute;
begin
  { Create IP connection }
  ipcon := TIPConnection.Create;

  { Create device object }
  lcd := TBrickletLCD16x2.Create(UID, ipcon);

  { Connect to brickd }
  ipcon.Connect(HOST, PORT);
  { Don't use device before ipcon is connected }

  { Register button pressed callback to procedure ButtonPressedCB }
  lcd.OnButtonPressed := {$ifdef FPC}@{$endif}ButtonPressedCB;

  { Register button released callback to procedure ButtonReleasedCB }
  lcd.OnButtonReleased := {$ifdef FPC}@{$endif}ButtonReleasedCB;

  WriteLn('Press key to exit');
  ReadLn;
  ipcon.Destroy; { Calls ipcon.Disconnect internally }
end;

begin
  e := TExample.Create;
  e.Execute;
  e.Destroy;
end.

Unicode

Download (ExampleUnicode.pas)

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
program ExampleUnicode;

{$ifdef MSWINDOWS}{$apptype CONSOLE}{$endif}
{$ifdef FPC}{$mode OBJFPC}{$H+}{$endif}

uses
  SysUtils, IPConnection, BrickletLCD16x2;

type
  TExample = class
  private
    ipcon: TIPConnection;
    lcd: TBrickletLCD16x2;
  public
    function WideStringToKS0066U(const text: WideString): string;
    procedure Execute;
  end;

const
  HOST = 'localhost';
  PORT = 4223;
  UID = 'XYZ'; { Change XYZ to the UID of your LCD 16x2 Bricklet }

var
  e: TExample;

function TExample.WideStringToKS0066U(const text: WideString): string;
var i, codePoint: longint; w: word; c: char; ks0066u: string;
begin
  i := 1;
  SetLength(ks0066u, 0);
  while (i <= Length(text)) do begin
    { WideString is UTF-16, handle surrogates }
    w := word(text[i]);
    if ((w >= $D800) and (w <= $DBFF)) then begin
      codePoint := $10000 + (w - $D800) * $400 + (w - $DC00);
      i := i + 2;
    end
    else begin
      codePoint := w;
      i := i + 1;
    end;
    { ASCII subset from JIS X 0201 }
    if ((codePoint >= $0020) and (codePoint <= $007E)) then begin
      { The LCD charset doesn't include '\' and '~', use similar characters instead }
      case codePoint of
        $005C: c := char($A4); { REVERSE SOLIDUS maps to IDEOGRAPHIC COMMA }
        $007E: c := char($2D); { TILDE maps to HYPHEN-MINUS }
        else   c := char(codePoint);
      end;
    end
    { Katakana subset from JIS X 0201 }
    else if ((codePoint >= $FF61) and (codePoint <= $FF9F)) then begin
      c := char(codePoint - $FEC0);
    end
    { Special characters }
    else begin
      case codePoint of
        $00A5: c := char($5C); { YEN SIGN }
        $2192: c := char($7E); { RIGHTWARDS ARROW }
        $2190: c := char($7F); { LEFTWARDS ARROW }
        $00B0: c := char($DF); { DEGREE SIGN maps to KATAKANA SEMI-VOICED SOUND MARK }
        $03B1: c := char($E0); { GREEK SMALL LETTER ALPHA }
        $00C4: c := char($E1); { LATIN CAPITAL LETTER A WITH DIAERESIS }
        $00E4: c := char($E1); { LATIN SMALL LETTER A WITH DIAERESIS }
        $00DF: c := char($E2); { LATIN SMALL LETTER SHARP S }
        $03B5: c := char($E3); { GREEK SMALL LETTER EPSILON }
        $00B5: c := char($E4); { MICRO SIGN }
        $03BC: c := char($E4); { GREEK SMALL LETTER MU }
        $03C2: c := char($E5); { GREEK SMALL LETTER FINAL SIGMA }
        $03C1: c := char($E6); { GREEK SMALL LETTER RHO }
        $221A: c := char($E8); { SQUARE ROOT }
        $00B9: c := char($E9); { SUPERSCRIPT ONE maps to SUPERSCRIPT (minus) ONE }
        $00A4: c := char($EB); { CURRENCY SIGN }
        $00A2: c := char($EC); { CENT SIGN }
        $2C60: c := char($ED); { LATIN CAPITAL LETTER L WITH DOUBLE BAR }
        $00F1: c := char($EE); { LATIN SMALL LETTER N WITH TILDE }
        $00D6: c := char($EF); { LATIN CAPITAL LETTER O WITH DIAERESIS }
        $00F6: c := char($EF); { LATIN SMALL LETTER O WITH DIAERESIS }
        $03F4: c := char($F2); { GREEK CAPITAL THETA SYMBOL }
        $221E: c := char($F3); { INFINITY }
        $03A9: c := char($F4); { GREEK CAPITAL LETTER OMEGA }
        $00DC: c := char($F5); { LATIN CAPITAL LETTER U WITH DIAERESIS }
        $00FC: c := char($F5); { LATIN SMALL LETTER U WITH DIAERESIS }
        $03A3: c := char($F6); { GREEK CAPITAL LETTER SIGMA }
        $03C0: c := char($F7); { GREEK SMALL LETTER PI }
        $0304: c := char($F8); { COMBINING MACRON }
        $00F7: c := char($FD); { DIVISION SIGN }
        $25A0: c := char($FF); { BLACK SQUARE }
        else   c := char($FF); { BLACK SQUARE }
      end
    end;
    { Special handling for 'x' followed by COMBINING MACRON }
    if (c = char($F8)) then begin
      if (ks0066u[Length(ks0066u) - 1] <> 'x') then begin
        c := char($FF); { BLACK SQUARE }
      end;
      if (Length(ks0066u) > 0) then begin
        SetLength(ks0066u, Length(ks0066u) - 1);
      end;
    end;
    ks0066u := ks0066u + c;
  end;
  result := ks0066u;
end;

procedure TExample.Execute;
begin
  { Create IP connection }
  ipcon := TIPConnection.Create;

  { Create device object }
  lcd := TBrickletLCD16x2.Create(UID, ipcon);

  { Connect to brickd }
  ipcon.Connect(HOST, PORT);
  { Don't use device before ipcon is connected }

  { Turn backlight on }
  lcd.BacklightOn;

  { Write a string using the WideStringToKS0066U function to map to the LCD charset }
  { Note: For the Free Pascal Compiler (and Lazarus) UTF8Decode is used to create a
          WideString. It assumes that your source file is UTF-8 encoded }
  lcd.WriteLine(0, 0, WideStringToKS0066U({$ifdef FPC}UTF8Decode{$endif}('Stromstärke: 5µA')));

  { Write a string directly including characters from the LCD charset }
  lcd.WriteLine(1, 0, 'Drehzahl: 1000s' + char($E9));

  WriteLn('Press key to exit');
  ReadLn;
  ipcon.Destroy; { Calls ipcon.Disconnect internally }
end;

begin
  e := TExample.Create;
  e.Execute;
  e.Destroy;
end.

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

constructor TBrickletLCD16x2.Create(const uid: string; ipcon: TIPConnection)
Parameters:
  • uid – Type: string
  • ipcon – Type: TIPConnection
Returns:
  • lcd16x2 – Type: TBrickletLCD16x2

Creates an object with the unique device ID uid:

lcd16x2 := TBrickletLCD16x2.Create('YOUR_DEVICE_UID', ipcon);

This object can then be used after the IP Connection is connected.

procedure TBrickletLCD16x2.WriteLine(const line: byte; const position: byte; const text: string)
Parameters:
  • line – Type: byte, Range: [0 to 1]
  • position – Type: byte, Range: [0 to 15]
  • text – Type: string, Length: up to 16

Writes text to a specific line with a specific position. 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 for details. The Unicode example above shows how to specify non-ASCII characters and how to translate from Unicode to the LCD charset.

procedure TBrickletLCD16x2.ClearDisplay

Deletes all characters from the display.

procedure TBrickletLCD16x2.BacklightOn

Turns the backlight on.

procedure TBrickletLCD16x2.BacklightOff

Turns the backlight off.

function TBrickletLCD16x2.IsBacklightOn: boolean
Returns:
  • backlight – Type: boolean

Returns true if the backlight is on and false otherwise.

Advanced Functions

procedure TBrickletLCD16x2.SetConfig(const cursor: boolean; const blinking: boolean)
Parameters:
  • cursor – Type: boolean, Default: false
  • blinking – Type: boolean, Default: 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.

procedure TBrickletLCD16x2.GetConfig(out cursor: boolean; out blinking: boolean)
Output Parameters:
  • cursor – Type: boolean, Default: false
  • blinking – Type: boolean, Default: false

Returns the configuration as set by SetConfig.

function TBrickletLCD16x2.IsButtonPressed(const button: byte): boolean
Parameters:
  • button – Type: byte, Range: [0 to 2]
Returns:
  • pressed – Type: boolean

Returns true if the button is pressed.

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

procedure TBrickletLCD16x2.SetCustomCharacter(const index: byte; const character: array [0..7] of byte)
Parameters:
  • index – Type: byte, Range: [0 to 7]
  • character – Type: array [0..7] of byte, Range: [0 to 31]

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 WriteLine by using the characters with the byte representation 8 ("\x08" or "\u0008") to 15 ("\x0F" or "\u000F").

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.

New in version 2.0.1 (Plugin).

function TBrickletLCD16x2.GetCustomCharacter(const index: byte): array [0..7] of byte
Parameters:
  • index – Type: byte, Range: [0 to 7]
Returns:
  • character – Type: array [0..7] of byte, Range: [0 to 31]

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

New in version 2.0.1 (Plugin).

procedure TBrickletLCD16x2.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)
Output Parameters:
  • uid – Type: string, Length: up to 8
  • connectedUid – Type: string, Length: up to 8
  • position – Type: char, Range: ['a' to 'h', 'i', 'z']
  • hardwareVersion – Type: array [0..2] of byte
    • 0: major – Type: byte, Range: [0 to 255]
    • 1: minor – Type: byte, Range: [0 to 255]
    • 2: revision – Type: byte, Range: [0 to 255]
  • firmwareVersion – Type: array [0..2] of byte
    • 0: major – Type: byte, Range: [0 to 255]
    • 1: minor – Type: byte, Range: [0 to 255]
    • 2: revision – Type: byte, Range: [0 to 255]
  • deviceIdentifier – Type: word, Range: [0 to 216 - 1]

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', 'd', 'e', 'f', 'g' or 'h' (Bricklet Port). The Raspberry Pi HAT (Zero) Brick is always at position 'i' and the Bricklet connected to an Isolator Bricklet is always as position 'z'.

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 procedure to an callback property of the device object:

procedure TExample.MyCallback(sender: TBrickletLCD16x2; const value: longint);
begin
  WriteLn(Format('Value: %d', [value]));
end;

lcd16x2.OnExample := {$ifdef FPC}@{$endif}example.MyCallback;

The available callback properties and their parameter types 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.

property TBrickletLCD16x2.OnButtonPressed
procedure(sender: TBrickletLCD16x2; const button: byte) of object;
Callback Parameters:
  • sender – Type: TBrickletLCD16x2
  • button – Type: byte, Range: [0 to 2]

This callback is triggered when a button is pressed. The parameter is the number of the button.

property TBrickletLCD16x2.OnButtonReleased
procedure(sender: TBrickletLCD16x2; const button: byte) of object;
Callback Parameters:
  • sender – Type: TBrickletLCD16x2
  • button – Type: byte, Range: [0 to 2]

This callback is triggered when a button is released. The parameter is the number of the button.

Virtual Functions

Virtual functions don't communicate with the device itself, but operate only on the API bindings device object. They can be called without the corresponding IP Connection object being connected.

function TBrickletLCD16x2.GetAPIVersion: array [0..2] of byte
Output Parameters:
  • apiVersion – Type: array [0..2] of byte
    • 0: major – Type: byte, Range: [0 to 255]
    • 1: minor – Type: byte, Range: [0 to 255]
    • 2: revision – Type: byte, Range: [0 to 255]

Returns the version of the API definition 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.

function TBrickletLCD16x2.GetResponseExpected(const functionId: byte): boolean
Parameters:
  • functionId – Type: byte, Range: See constants
Returns:
  • responseExpected – Type: 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 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 sent and errors are silently ignored, because they cannot be detected.

The following constants are available for this function:

For functionId:

  • BRICKLET_LCD_16X2_FUNCTION_WRITE_LINE = 1
  • BRICKLET_LCD_16X2_FUNCTION_CLEAR_DISPLAY = 2
  • BRICKLET_LCD_16X2_FUNCTION_BACKLIGHT_ON = 3
  • BRICKLET_LCD_16X2_FUNCTION_BACKLIGHT_OFF = 4
  • BRICKLET_LCD_16X2_FUNCTION_SET_CONFIG = 6
  • BRICKLET_LCD_16X2_FUNCTION_SET_CUSTOM_CHARACTER = 11
procedure TBrickletLCD16x2.SetResponseExpected(const functionId: byte; const responseExpected: boolean)
Parameters:
  • functionId – Type: byte, Range: See constants
  • responseExpected – Type: 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.

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 sent and errors are silently ignored, because they cannot be detected.

The following constants are available for this function:

For functionId:

  • BRICKLET_LCD_16X2_FUNCTION_WRITE_LINE = 1
  • BRICKLET_LCD_16X2_FUNCTION_CLEAR_DISPLAY = 2
  • BRICKLET_LCD_16X2_FUNCTION_BACKLIGHT_ON = 3
  • BRICKLET_LCD_16X2_FUNCTION_BACKLIGHT_OFF = 4
  • BRICKLET_LCD_16X2_FUNCTION_SET_CONFIG = 6
  • BRICKLET_LCD_16X2_FUNCTION_SET_CUSTOM_CHARACTER = 11
procedure TBrickletLCD16x2.SetResponseExpectedAll(const responseExpected: boolean)
Parameters:
  • responseExpected – Type: boolean

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

Constants

const BRICKLET_LCD_16X2_DEVICE_IDENTIFIER

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

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

const BRICKLET_LCD_16X2_DEVICE_DISPLAY_NAME

This constant represents the human readable name of a LCD 16x2 Bricklet.