Java - LCD 16x2 Bricklet – Tinkerforge

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# Java - LCD 16x2 Bricklet

This is the description of the Java 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 Java API bindings is part of their general description.

## Examples

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

### Hello World

Download (ExampleHelloWorld.java)

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    import com.tinkerforge.BrickletLCD16x2;
    import com.tinkerforge.IPConnection;

    public class ExampleHelloWorld {
        private static final String HOST = "localhost";
        private static final int PORT = 4223;
        private static final String UID = "ABC"; // Change to your UID

        // Note: To make the example code cleaner we do not handle exceptions. Exceptions you
        //       might normally want to catch are described in the documentation
        public static void main(String args[]) throws Exception {
            IPConnection ipcon = new IPConnection(); // Create IP connection
            BrickletLCD16x2 lcd = new BrickletLCD16x2(UID, ipcon); // Create device object

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

            // Turn backlight on
            lcd.backlightOn();

            // Write "Hello World"
            lcd.writeLine((short)0, (short)0, "Hello World");

            System.out.println("Press key to exit"); System.in.read();
            ipcon.disconnect();
        }
    }

### Button Callback

Download (ExampleButtonCallback.java)

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    import com.tinkerforge.BrickletLCD16x2;
    import com.tinkerforge.IPConnection;

    public class ExampleButtonCallback {
        private static final String HOST = "localhost";
        private static final int PORT = 4223;
        private static final String UID = "ABC"; // Change to your UID

        // Note: To make the example code cleaner we do not handle exceptions. Exceptions you
        //       might normally want to catch are described in the documentation
        public static void main(String args[]) throws Exception {
            IPConnection ipcon = new IPConnection(); // Create IP connection
            BrickletLCD16x2 lcd = new BrickletLCD16x2(UID, ipcon); // Create device object

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

            // Add and implement listener for pressed and released events
            lcd.addButtonPressedListener(new BrickletLCD16x2.ButtonPressedListener() {
                public void buttonPressed(short button) {
                    System.out.println("Pressed: " + button);
                }
            });
            lcd.addButtonReleasedListener(new BrickletLCD16x2.ButtonReleasedListener() {
                public void buttonReleased(short button) {
                    System.out.println("Released: " + button);
                }
            });

            System.out.println("Press key to exit"); System.in.read();
            ipcon.disconnect();
        }
    }

### Unicode

Download (ExampleUnicode.java)

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    import com.tinkerforge.BrickletLCD16x2;
    import com.tinkerforge.IPConnection;

    public class ExampleUnicode {
        private static final String HOST = "localhost";
        private static final int PORT = 4223;
        private static final String UID = "6mJ"; // Change to your UID

        // Maps a normal UTF-16 encoded string to the LCD charset
        static String utf16ToKS0066U(String utf16)
        {
            String ks0066u = "";
            char c;

            for (int i = 0; i < utf16.length(); i++) {
                int codePoint = utf16.codePointAt(i);

                if (Character.isHighSurrogate(utf16.charAt(i))) {
                    // Skip low surrogate
                    i++;
                }

                // ASCII subset from JIS X 0201
                if (codePoint >= 0x0020 && codePoint <= 0x007e) {
                    // The LCD charset doesn't include '\' and '~', use similar characters instead
                    switch (codePoint) {
                    case 0x005c: c = (char)0xa4; break; // REVERSE SOLIDUS maps to IDEOGRAPHIC COMMA
                    case 0x007e: c = (char)0x2d; break; // TILDE maps to HYPHEN-MINUS
                    default: c = (char)codePoint; break;
                    }
                }
                // Katakana subset from JIS X 0201
                else if (codePoint >= 0xff61 && codePoint <= 0xff9f) {
                    c = (char)(codePoint - 0xfec0);
                }
                // Special characters
                else {
                    switch (codePoint) {
                    case 0x00a5: c = (char)0x5c; break; // YEN SIGN
                    case 0x2192: c = (char)0x7e; break; // RIGHTWARDS ARROW
                    case 0x2190: c = (char)0x7f; break; // LEFTWARDS ARROW
                    case 0x00b0: c = (char)0xdf; break; // DEGREE SIGN maps to KATAKANA SEMI-VOICED SOUND MARK
                    case 0x03b1: c = (char)0xe0; break; // GREEK SMALL LETTER ALPHA
                    case 0x00c4: c = (char)0xe1; break; // LATIN CAPITAL LETTER A WITH DIAERESIS
                    case 0x00e4: c = (char)0xe1; break; // LATIN SMALL LETTER A WITH DIAERESIS
                    case 0x00df: c = (char)0xe2; break; // LATIN SMALL LETTER SHARP S
                    case 0x03b5: c = (char)0xe3; break; // GREEK SMALL LETTER EPSILON
                    case 0x00b5: c = (char)0xe4; break; // MICRO SIGN
                    case 0x03bc: c = (char)0xe4; break; // GREEK SMALL LETTER MU
                    case 0x03c2: c = (char)0xe5; break; // GREEK SMALL LETTER FINAL SIGMA
                    case 0x03c1: c = (char)0xe6; break; // GREEK SMALL LETTER RHO
                    case 0x221a: c = (char)0xe8; break; // SQUARE ROOT
                    case 0x00b9: c = (char)0xe9; break; // SUPERSCRIPT ONE maps to SUPERSCRIPT (minus) ONE
                    case 0x00a4: c = (char)0xeb; break; // CURRENCY SIGN
                    case 0x00a2: c = (char)0xec; break; // CENT SIGN
                    case 0x2c60: c = (char)0xed; break; // LATIN CAPITAL LETTER L WITH DOUBLE BAR
                    case 0x00f1: c = (char)0xee; break; // LATIN SMALL LETTER N WITH TILDE
                    case 0x00d6: c = (char)0xef; break; // LATIN CAPITAL LETTER O WITH DIAERESIS
                    case 0x00f6: c = (char)0xef; break; // LATIN SMALL LETTER O WITH DIAERESIS
                    case 0x03f4: c = (char)0xf2; break; // GREEK CAPITAL THETA SYMBOL
                    case 0x221e: c = (char)0xf3; break; // INFINITY
                    case 0x03a9: c = (char)0xf4; break; // GREEK CAPITAL LETTER OMEGA
                    case 0x00dc: c = (char)0xf5; break; // LATIN CAPITAL LETTER U WITH DIAERESIS
                    case 0x00fc: c = (char)0xf5; break; // LATIN SMALL LETTER U WITH DIAERESIS
                    case 0x03a3: c = (char)0xf6; break; // GREEK CAPITAL LETTER SIGMA
                    case 0x03c0: c = (char)0xf7; break; // GREEK SMALL LETTER PI
                    case 0x0304: c = (char)0xf8; break; // COMBINING MACRON
                    case 0x00f7: c = (char)0xfd; break; // DIVISION SIGN

                    default:
                    case 0x25a0: c = (char)0xff; break; // BLACK SQUARE
                    }
                }

                // Special handling for 'x' followed by COMBINING MACRON
                if (c == (char)0xf8) {
                    if (!ks0066u.endsWith("x")) {
                        c = (char)0xff; // BLACK SQUARE
                    }

                    if (ks0066u.length() > 0) {
                        ks0066u = ks0066u.substring(0, ks0066u.length() - 1);
                    }
                }

                ks0066u += c;
            }

            return ks0066u;
        }

        // Note: To make the example code cleaner we do not handle exceptions. Exceptions you
        //       might normally want to catch are described in the documentation
        public static void main(String args[]) throws Exception {
            IPConnection ipcon = new IPConnection(); // Create IP connection
            BrickletLCD16x2 lcd = new BrickletLCD16x2(UID, ipcon); // Create device object

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

            // Turn backlight on
            lcd.backlightOn();

            // Write a string using the utf16ToKS0066U function to map to the LCD charset
            lcd.writeLine((short)0, (short)0, utf16ToKS0066U("Stromstärke: 5µA"));

            // Write a string directly including characters from the LCD charset
            lcd.writeLine((short)1, (short)0, "Drehzahl: 1000s\u00e9");

            System.out.println("Press key to exit"); System.in.read();
            ipcon.disconnect();
        }
    }

## API

Generally, every method of the Java bindings that returns a value can throw a `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 unplugs the device). However, if a wireless connection is used, timeouts will occur if the distance to the device gets too big.

Beside the `TimeoutException` there is also a `NotConnectedException` that is thrown if a method needs to communicate with the device while the IP Connection is not connected.

Since Java does not support multiple return values and return by reference is not possible for primitive types, we use small classes that only consist of member variables. The member variables of the returned objects are described in the corresponding method descriptions.

The package for all Brick/Bricklet bindings and the IP Connection is `com.tinkerforge.*`

All methods listed below are thread-safe.

### Basic Functions

public class `BrickletLCD16x2`(String uid, IPConnection ipcon)

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

      BrickletLCD16x2 lcd16x2 = new BrickletLCD16x2("YOUR_DEVICE_UID", ipcon);

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

public void `writeLine`(short line, short position, String text)

  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 for details. The Unicode example above shows how to specify non-ASCII characters and how to translate from Unicode to the LCD charset.

public void `clearDisplay`()

  Deletes all characters from the display.

public void `backlightOn`()

  Turns the backlight on.

public void `backlightOff`()

  Turns the backlight off.

public boolean `isBacklightOn`()

  Returns true if the backlight is on and false otherwise.

### Advanced Functions

public void `setConfig`(boolean cursor, boolean blinking)

  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).

public BrickletLCD16x2.Config `getConfig`()

  Returns the configuration as set by `setConfig()`.

  The returned object has the public member variables `boolean cursor` and `boolean blinking`.

public boolean `isButtonPressed`(short button)

  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 `ButtonPressedListener` and `ButtonReleasedListener` listeners.

public void `setCustomCharacter`(short index, short[] character)

  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 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.

  New in version 2.0.1 (Plugin).

public short[] `getCustomCharacter`(short index)

  Returns the custom character for a given index, as set with `setCustomCharacter()`.

  New in version 2.0.1 (Plugin).

public short[] `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.

public boolean `getResponseExpected`(short 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 listener 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.

public void `setResponseExpected`(short functionId, boolean 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 listener configuration functions (default value: true). For getter functions it is always enabled and listeners 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

public void `setResponseExpectedAll`(boolean responseExpected)

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

public BrickletLCD16x2.Identity `getIdentity`()

  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.

  The returned object has the public member variables `String uid`, `String connectedUid`, `char position`, `short[] hardwareVersion`, `short[] firmwareVersion` and `int deviceIdentifier`.

### Listeners

Listeners can be registered to receive time critical or recurring data from the device. The registration is done with "add*Listener" functions of the device object.

The parameter is a listener class object, for example:

    device.addExampleListener(new BrickletLCD16x2.ExampleListener() {
        public void property(int value) {
            System.out.println("Value: " + value);
        }
    });

The available listener classes with inherent methods to be overwritten are described below. It is possible to add several listeners and to remove them with the corresponding "remove*Listener" function.

Note

Using listeners 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.

public class `BrickletLCD16x2.ButtonPressedListener`()

  This listener can be added with the `addButtonPressedListener()` function. An added listener can be removed with the `removeButtonPressedListener()` function.

  public void `buttonPressed`(short button)

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

public class `BrickletLCD16x2.ButtonReleasedListener`()

  This listener can be added with the `addButtonReleasedListener()` function. An added listener can be removed with the `removeButtonReleasedListener()` function.

  public void `buttonReleased`(short button)

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

### Constants

public static final int `BrickletLCD16x2.DEVICE_IDENTIFIER`

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

  The `getIdentity()` function and the `EnumerateListener` listener of the IP Connection have a `deviceIdentifier` parameter to specify the Brick's or Bricklet's type.

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