Java - Dual Button Bricklet

This is the description of the Java API bindings for the Dual Button Bricklet. General information and technical specifications for the Dual Button 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).

Callback

Download (ExampleCallback.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
import com.tinkerforge.IPConnection;
import com.tinkerforge.BrickletDualButton;

public class ExampleCallback {
    private static final String HOST = "localhost";
    private static final int PORT = 4223;

    // Change XYZ to the UID of your Dual Button 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
        BrickletDualButton db = new BrickletDualButton(UID, ipcon); // Create device object

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

        // Add state changed listener
        db.addStateChangedListener(new BrickletDualButton.StateChangedListener() {
            public void stateChanged(short buttonL, short buttonR, short ledL,
                                     short ledR) {
                if(buttonL == BrickletDualButton.BUTTON_STATE_PRESSED) {
                    System.out.println("Left Button: Pressed");
                } else if(buttonL == BrickletDualButton.BUTTON_STATE_RELEASED) {
                    System.out.println("Left Button: Released");
                }

                if(buttonR == BrickletDualButton.BUTTON_STATE_PRESSED) {
                    System.out.println("Right Button: Pressed");
                } else if(buttonR == BrickletDualButton.BUTTON_STATE_RELEASED) {
                    System.out.println("Right Button: Released");
                }

                System.out.println("");
            }
        });

        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 BrickletDualButton(String uid, IPConnection ipcon)

Creates an object with the unique device ID uid:

BrickletDualButton dualButton = new BrickletDualButton("YOUR_DEVICE_UID", ipcon);

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

public void setLEDState(short ledL, short ledR)

Sets the state of the LEDs. Possible states are:

  • 0 = AutoToggleOn: Enables auto toggle with initially enabled LED.
  • 1 = AutoToggleOff: Activates auto toggle with initially disabled LED.
  • 2 = On: Enables LED (auto toggle is disabled).
  • 3 = Off: Disables LED (auto toggle is disabled).

In auto toggle mode the LED is toggled automatically at each press of a button.

If you just want to set one of the LEDs and don't know the current state of the other LED, you can get the state with getLEDState() or you can use setSelectedLEDState().

The default value is (1, 1).

The following constants are available for this function:

  • BrickletDualButton.LED_STATE_AUTO_TOGGLE_ON = 0
  • BrickletDualButton.LED_STATE_AUTO_TOGGLE_OFF = 1
  • BrickletDualButton.LED_STATE_ON = 2
  • BrickletDualButton.LED_STATE_OFF = 3
public BrickletDualButton.LEDState getLEDState()

Returns the current state of the LEDs, as set by setLEDState().

The following constants are available for this function:

  • BrickletDualButton.LED_STATE_AUTO_TOGGLE_ON = 0
  • BrickletDualButton.LED_STATE_AUTO_TOGGLE_OFF = 1
  • BrickletDualButton.LED_STATE_ON = 2
  • BrickletDualButton.LED_STATE_OFF = 3

The returned object has the public member variables short ledL and short ledR.

public BrickletDualButton.ButtonState getButtonState()

Returns the current state for both buttons. Possible states are:

  • 0 = pressed
  • 1 = released

The following constants are available for this function:

  • BrickletDualButton.BUTTON_STATE_PRESSED = 0
  • BrickletDualButton.BUTTON_STATE_RELEASED = 1

The returned object has the public member variables short buttonL and short buttonR.

Advanced Functions

public void setSelectedLEDState(short led, short state)

Sets the state of the selected LED (0 or 1).

The other LED remains untouched.

The following constants are available for this function:

  • BrickletDualButton.LED_LEFT = 0
  • BrickletDualButton.LED_RIGHT = 1
  • BrickletDualButton.LED_STATE_AUTO_TOGGLE_ON = 0
  • BrickletDualButton.LED_STATE_AUTO_TOGGLE_OFF = 1
  • BrickletDualButton.LED_STATE_ON = 2
  • BrickletDualButton.LED_STATE_OFF = 3
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.

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:

  • BrickletDualButton.FUNCTION_SET_LED_STATE = 1
  • BrickletDualButton.FUNCTION_SET_SELECTED_LED_STATE = 5
public void setResponseExpectedAll(boolean responseExpected)

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

public BrickletDualButton.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 BrickletDualButton.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 BrickletDualButton.StateChangedListener()

This listener can be added with the addStateChangedListener() function. An added listener can be removed with the removeStateChangedListener() function.

public void stateChanged(short buttonL, short buttonR, short ledL, short ledR)

This listener is called whenever a button is pressed.

Possible states for buttons are:

  • 0 = pressed
  • 1 = released

Possible states for LEDs are:

  • 0 = AutoToggleOn: Auto toggle enabled and LED on.
  • 1 = AutoToggleOff: Auto toggle enabled and LED off.
  • 2 = On: LED on (auto toggle is disabled).
  • 3 = Off: LED off (auto toggle is disabled).

The following constants are available for this function:

  • BrickletDualButton.BUTTON_STATE_PRESSED = 0
  • BrickletDualButton.BUTTON_STATE_RELEASED = 1
  • BrickletDualButton.LED_STATE_AUTO_TOGGLE_ON = 0
  • BrickletDualButton.LED_STATE_AUTO_TOGGLE_OFF = 1
  • BrickletDualButton.LED_STATE_ON = 2
  • BrickletDualButton.LED_STATE_OFF = 3

Constants

public static final int BrickletDualButton.DEVICE_IDENTIFIER

This constant is used to identify a Dual Button 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.

public static final String BrickletDualButton.DEVICE_DISPLAY_NAME

This constant represents the human readable name of a Dual Button Bricklet.