This is the description of the Java 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 Java API bindings is part of their general description.
The example code below is Public Domain (CC0 1.0).
Download (ExampleHelloWorld.java)
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 | import com.tinkerforge.IPConnection;
import com.tinkerforge.BrickletLCD20x4;
public class ExampleHelloWorld {
private static final String HOST = "localhost";
private static final int PORT = 4223;
// Change XYZ to the UID of your LCD 20x4 Bricklet
private static final String UID = "XYZ";
// 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
BrickletLCD20x4 lcd = new BrickletLCD20x4(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();
}
}
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Download (ExampleButtonCallback.java)
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 | import com.tinkerforge.IPConnection;
import com.tinkerforge.BrickletLCD20x4;
public class ExampleButtonCallback {
private static final String HOST = "localhost";
private static final int PORT = 4223;
// Change XYZ to the UID of your LCD 20x4 Bricklet
private static final String UID = "XYZ";
// 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
BrickletLCD20x4 lcd = new BrickletLCD20x4(UID, ipcon); // Create device object
ipcon.connect(HOST, PORT); // Connect to brickd
// Don't use device before ipcon is connected
// Add button pressed listener
lcd.addButtonPressedListener(new BrickletLCD20x4.ButtonPressedListener() {
public void buttonPressed(short button) {
System.out.println("Button Pressed: " + button);
}
});
// Add button released listener
lcd.addButtonReleasedListener(new BrickletLCD20x4.ButtonReleasedListener() {
public void buttonReleased(short button) {
System.out.println("Button Released: " + button);
}
});
System.out.println("Press key to exit"); System.in.read();
ipcon.disconnect();
}
}
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Download (ExampleUnicode.java)
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 | import com.tinkerforge.IPConnection;
import com.tinkerforge.BrickletLCD20x4;
public class ExampleUnicode {
private static final String HOST = "localhost";
private static final int PORT = 4223;
// Change XYZ to the UID of your LCD 20x4 Bricklet
private static final String UID = "XYZ";
// 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
BrickletLCD20x4 lcd = new BrickletLCD20x4(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 some strings using the utf16ToKS0066U function to map to the LCD charset
lcd.writeLine((short)0, (short)0, utf16ToKS0066U("Stromstärke: 17µA"));
lcd.writeLine((short)1, (short)0, utf16ToKS0066U("Temperatur: 23°C"));
// Write a string directly including characters from the LCD charset
lcd.writeLine((short)2, (short)0, "Drehzahl: 750min\u00e9");
System.out.println("Press key to exit"); System.in.read();
ipcon.disconnect();
}
}
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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.
Creates an object with the unique device ID uid:
BrickletLCD20x4 lcd20x4 = new BrickletLCD20x4("YOUR_DEVICE_UID", ipcon);
This object can then be used after the IP Connection is connected (see examples above).
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.
Deletes all characters from the display.
Turns the backlight on.
Turns the backlight off.
Returns true if the backlight is on and false otherwise.
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).
Returns the configuration as set by setConfig().
The returned object has the public member variables boolean cursor and boolean blinking.
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 ButtonPressedListener and ButtonReleasedListener listeners.
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:
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).
Returns the custom character for a given index, as set with setCustomCharacter().
New in version 2.0.1 (Plugin).
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).
Returns the default text for a given line (0-3) as set by setDefaultText().
New in version 2.0.2 (Plugin).
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).
Returns the current value of the default text counter.
New in version 2.0.2 (Plugin).
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.
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.
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.
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:
Changes the response expected flag for all setter and listener configuration functions of this device at once.
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 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 BrickletLCD20x4.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.
This listener can be added with the addButtonPressedListener() function. An added listener can be removed with the removeButtonPressedListener() function.
This listener 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).
This listener can be added with the addButtonReleasedListener() function. An added listener can be removed with the removeButtonReleasedListener() function.
This listener 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).
This constant is used to identify a LCD 20x4 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.
This constant represents the human readable name of a LCD 20x4 Bricklet.