Java - Joystick Bricklet

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

Simple

Download (ExampleSimple.java)

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import com.tinkerforge.IPConnection;
import com.tinkerforge.BrickletJoystick;
import com.tinkerforge.BrickletJoystick.Position;

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

    // Change XYZ to the UID of your Joystick 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
        BrickletJoystick j = new BrickletJoystick(UID, ipcon); // Create device object

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

        // Get current position
        Position position = j.getPosition(); // Can throw com.tinkerforge.TimeoutException

        System.out.println("Position [X]: " + position.x);
        System.out.println("Position [Y]: " + position.y);

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

Callback

Download (ExampleCallback.java)

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import com.tinkerforge.IPConnection;
import com.tinkerforge.BrickletJoystick;

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

    // Change XYZ to the UID of your Joystick 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
        BrickletJoystick j = new BrickletJoystick(UID, ipcon); // Create device object

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

        // Add pressed listener
        j.addPressedListener(new BrickletJoystick.PressedListener() {
            public void pressed() {
                System.out.println("Pressed");
            }
        });

        // Add released listener
        j.addReleasedListener(new BrickletJoystick.ReleasedListener() {
            public void released() {
                System.out.println("Released");
            }
        });

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

Find Borders

Download (ExampleFindBorders.java)

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import com.tinkerforge.IPConnection;
import com.tinkerforge.BrickletJoystick;

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

    // Change XYZ to the UID of your Joystick 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
        BrickletJoystick j = new BrickletJoystick(UID, ipcon); // Create device object

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

        // Get threshold callbacks with a debounce time of 0.2 seconds (200ms)
        j.setDebouncePeriod(200);

        // Add position reached listener
        j.addPositionReachedListener(new BrickletJoystick.PositionReachedListener() {
            public void positionReached(short x, short y) {
                if(y == 100) {
                    System.out.println("Top");
                } else if(y == -100) {
                    System.out.println("Bottom");
                }

                if(x == 100) {
                    System.out.println("Right");
                } else if(x == -100) {
                    System.out.println("Left");
                }

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

        // Configure threshold for position "outside of -99, -99 to 99, 99"
        j.setPositionCallbackThreshold('o', (short)(-99), (short)99, (short)(-99),
                                       (short)99);

        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 BrickletJoystick(String uid, IPConnection ipcon)

Creates an object with the unique device ID uid:

BrickletJoystick joystick = new BrickletJoystick("YOUR_DEVICE_UID", ipcon);

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

public BrickletJoystick.Position getPosition()

Returns the position of the Joystick. The value ranges between -100 and 100 for both axis. The middle position of the joystick is x=0, y=0. The returned values are averaged and calibrated (see calibrate()).

If you want to get the position periodically, it is recommended to use the PositionListener listener and set the period with setPositionCallbackPeriod().

The returned object has the public member variables short x and short y.

public boolean isPressed()

Returns true if the button is pressed and false otherwise.

It is recommended to use the PressedListener and ReleasedListener listeners to handle the button.

Advanced Functions

public BrickletJoystick.AnalogValue getAnalogValue()

Returns the values as read by a 12-bit analog-to-digital converter. The values are between 0 and 4095 for both axis.

Note

The values returned by getPosition() are averaged over several samples to yield less noise, while getAnalogValue() gives back raw unfiltered analog values. The only reason to use getAnalogValue() is, if you need the full resolution of the analog-to-digital converter.

If you want the analog values periodically, it is recommended to use the AnalogValueListener listener and set the period with setAnalogValueCallbackPeriod().

The returned object has the public member variables int x and int y.

public void calibrate()

Calibrates the middle position of the Joystick. If your Joystick Bricklet does not return x=0 and y=0 in the middle position, call this function while the Joystick is standing still in the middle position.

The resulting calibration will be saved on the EEPROM of the Joystick Bricklet, thus you only have to calibrate it once.

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:

  • BrickletJoystick.FUNCTION_CALIBRATE = 4
  • BrickletJoystick.FUNCTION_SET_POSITION_CALLBACK_PERIOD = 5
  • BrickletJoystick.FUNCTION_SET_ANALOG_VALUE_CALLBACK_PERIOD = 7
  • BrickletJoystick.FUNCTION_SET_POSITION_CALLBACK_THRESHOLD = 9
  • BrickletJoystick.FUNCTION_SET_ANALOG_VALUE_CALLBACK_THRESHOLD = 11
  • BrickletJoystick.FUNCTION_SET_DEBOUNCE_PERIOD = 13
public void setResponseExpectedAll(boolean responseExpected)

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

public BrickletJoystick.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.

Listener Configuration Functions

public void setPositionCallbackPeriod(long period)

Sets the period in ms with which the PositionListener listener is triggered periodically. A value of 0 turns the listener off.

The PositionListener listener is only triggered if the position has changed since the last triggering.

The default value is 0.

public long getPositionCallbackPeriod()

Returns the period as set by setPositionCallbackPeriod().

public void setAnalogValueCallbackPeriod(long period)

Sets the period in ms with which the AnalogValueListener listener is triggered periodically. A value of 0 turns the listener off.

The AnalogValueListener listener is only triggered if the analog values have changed since the last triggering.

The default value is 0.

public long getAnalogValueCallbackPeriod()

Returns the period as set by setAnalogValueCallbackPeriod().

public void setPositionCallbackThreshold(char option, short minX, short maxX, short minY, short maxY)

Sets the thresholds for the PositionReachedListener listener.

The following options are possible:

Option Description
'x' Listener is turned off
'o' Listener is triggered when the position is outside the min and max values
'i' Listener is triggered when the position is inside the min and max values
'<' Listener is triggered when the position is smaller than the min values (max is ignored)
'>' Listener is triggered when the position is greater than the min values (max is ignored)

The default value is ('x', 0, 0, 0, 0).

The following constants are available for this function:

  • BrickletJoystick.THRESHOLD_OPTION_OFF = 'x'
  • BrickletJoystick.THRESHOLD_OPTION_OUTSIDE = 'o'
  • BrickletJoystick.THRESHOLD_OPTION_INSIDE = 'i'
  • BrickletJoystick.THRESHOLD_OPTION_SMALLER = '<'
  • BrickletJoystick.THRESHOLD_OPTION_GREATER = '>'
public BrickletJoystick.PositionCallbackThreshold getPositionCallbackThreshold()

Returns the threshold as set by setPositionCallbackThreshold().

The following constants are available for this function:

  • BrickletJoystick.THRESHOLD_OPTION_OFF = 'x'
  • BrickletJoystick.THRESHOLD_OPTION_OUTSIDE = 'o'
  • BrickletJoystick.THRESHOLD_OPTION_INSIDE = 'i'
  • BrickletJoystick.THRESHOLD_OPTION_SMALLER = '<'
  • BrickletJoystick.THRESHOLD_OPTION_GREATER = '>'

The returned object has the public member variables char option, short minX, short maxX, short minY and short maxY.

public void setAnalogValueCallbackThreshold(char option, int minX, int maxX, int minY, int maxY)

Sets the thresholds for the AnalogValueReachedListener listener.

The following options are possible:

Option Description
'x' Listener is turned off
'o' Listener is triggered when the analog values are outside the min and max values
'i' Listener is triggered when the analog values are inside the min and max values
'<' Listener is triggered when the analog values are smaller than the min values (max is ignored)
'>' Listener is triggered when the analog values are greater than the min values (max is ignored)

The default value is ('x', 0, 0, 0, 0).

The following constants are available for this function:

  • BrickletJoystick.THRESHOLD_OPTION_OFF = 'x'
  • BrickletJoystick.THRESHOLD_OPTION_OUTSIDE = 'o'
  • BrickletJoystick.THRESHOLD_OPTION_INSIDE = 'i'
  • BrickletJoystick.THRESHOLD_OPTION_SMALLER = '<'
  • BrickletJoystick.THRESHOLD_OPTION_GREATER = '>'
public BrickletJoystick.AnalogValueCallbackThreshold getAnalogValueCallbackThreshold()

Returns the threshold as set by setAnalogValueCallbackThreshold().

The following constants are available for this function:

  • BrickletJoystick.THRESHOLD_OPTION_OFF = 'x'
  • BrickletJoystick.THRESHOLD_OPTION_OUTSIDE = 'o'
  • BrickletJoystick.THRESHOLD_OPTION_INSIDE = 'i'
  • BrickletJoystick.THRESHOLD_OPTION_SMALLER = '<'
  • BrickletJoystick.THRESHOLD_OPTION_GREATER = '>'

The returned object has the public member variables char option, int minX, int maxX, int minY and int maxY.

public void setDebouncePeriod(long debounce)

Sets the period in ms with which the threshold listeners

are triggered, if the thresholds

keep being reached.

The default value is 100.

public long getDebouncePeriod()

Returns the debounce period as set by setDebouncePeriod().

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 BrickletJoystick.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 BrickletJoystick.PositionListener()

This listener can be added with the addPositionListener() function. An added listener can be removed with the removePositionListener() function.

public void position(short x, short y)

This listener is triggered periodically with the period that is set by setPositionCallbackPeriod(). The parameter is the position of the Joystick.

The PositionListener listener is only triggered if the position has changed since the last triggering.

public class BrickletJoystick.AnalogValueListener()

This listener can be added with the addAnalogValueListener() function. An added listener can be removed with the removeAnalogValueListener() function.

public void analogValue(int x, int y)

This listener is triggered periodically with the period that is set by setAnalogValueCallbackPeriod(). The parameters are the analog values of the Joystick.

The AnalogValueListener listener is only triggered if the values have changed since the last triggering.

public class BrickletJoystick.PositionReachedListener()

This listener can be added with the addPositionReachedListener() function. An added listener can be removed with the removePositionReachedListener() function.

public void positionReached(short x, short y)

This listener is triggered when the threshold as set by setPositionCallbackThreshold() is reached. The parameters are the position of the Joystick.

If the threshold keeps being reached, the listener is triggered periodically with the period as set by setDebouncePeriod().

public class BrickletJoystick.AnalogValueReachedListener()

This listener can be added with the addAnalogValueReachedListener() function. An added listener can be removed with the removeAnalogValueReachedListener() function.

public void analogValueReached(int x, int y)

This listener is triggered when the threshold as set by setAnalogValueCallbackThreshold() is reached. The parameters are the analog values of the Joystick.

If the threshold keeps being reached, the listener is triggered periodically with the period as set by setDebouncePeriod().

public class BrickletJoystick.PressedListener()

This listener can be added with the addPressedListener() function. An added listener can be removed with the removePressedListener() function.

public void pressed()

This listener is triggered when the button is pressed.

public class BrickletJoystick.ReleasedListener()

This listener can be added with the addReleasedListener() function. An added listener can be removed with the removeReleasedListener() function.

public void released()

This listener is triggered when the button is released.

Constants

public static final int BrickletJoystick.DEVICE_IDENTIFIER

This constant is used to identify a Joystick 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 BrickletJoystick.DEVICE_DISPLAY_NAME

This constant represents the human readable name of a Joystick Bricklet.