Java - Rotary Poti Bricklet

This is the description of the Java API bindings for the Rotary Poti Bricklet. General information and technical specifications for the Rotary Poti 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.BrickletRotaryPoti;

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

    // Change XYZ to the UID of your Rotary Poti 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
        BrickletRotaryPoti rp = new BrickletRotaryPoti(UID, ipcon); // Create device object

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

        // Get current position
        short position = rp.getPosition(); // Can throw com.tinkerforge.TimeoutException
        System.out.println("Position: " + position); // Range: -150 to 150

        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.BrickletRotaryPoti;

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

    // Change XYZ to the UID of your Rotary Poti 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
        BrickletRotaryPoti rp = new BrickletRotaryPoti(UID, ipcon); // Create device object

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

        // Add position listener
        rp.addPositionListener(new BrickletRotaryPoti.PositionListener() {
            public void position(short position) {
                System.out.println("Position: " + position); // Range: -150 to 150
            }
        });

        // Set period for position callback to 0.05s (50ms)
        // Note: The position callback is only called every 0.05 seconds
        //       if the position has changed since the last call!
        rp.setPositionCallbackPeriod(50);

        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

class BrickletRotaryPoti(String uid, IPConnection ipcon)
Parameters:
  • uid – Type: String
  • ipcon – Type: IPConnection
Returns:
  • rotaryPoti – Type: BrickletRotaryPoti

Creates an object with the unique device ID uid:

BrickletRotaryPoti rotaryPoti = new BrickletRotaryPoti("YOUR_DEVICE_UID", ipcon);

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

short BrickletRotaryPoti.getPosition()
Returns:
  • position – Type: short, Unit: 1 °, Range: [-150 to 150]

Returns the position of the rotary potentiometer. The value is between -150° (turned left) and 150° (turned right).

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

Advanced Functions

int BrickletRotaryPoti.getAnalogValue()
Returns:
  • value – Type: int, Range: [0 to 4096]

Returns the value as read by a 12-bit analog-to-digital converter.

Note

The value returned by getPosition() is 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 value periodically, it is recommended to use the AnalogValueListener listener and set the period with setAnalogValueCallbackPeriod().

BrickletRotaryPoti.Identity BrickletRotaryPoti.getIdentity()
Return Object:
  • 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: short[], Length: 3
    • 0: major – Type: short, Range: [0 to 255]
    • 1: minor – Type: short, Range: [0 to 255]
    • 2: revision – Type: short, Range: [0 to 255]
  • firmwareVersion – Type: short[], Length: 3
    • 0: major – Type: short, Range: [0 to 255]
    • 1: minor – Type: short, Range: [0 to 255]
    • 2: revision – Type: short, Range: [0 to 255]
  • deviceIdentifier – Type: int, 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.

Listener Configuration Functions

void BrickletRotaryPoti.setPositionCallbackPeriod(long period)
Parameters:
  • period – Type: long, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0

Sets the period 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.

long BrickletRotaryPoti.getPositionCallbackPeriod()
Returns:
  • period – Type: long, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0

Returns the period as set by setPositionCallbackPeriod().

void BrickletRotaryPoti.setAnalogValueCallbackPeriod(long period)
Parameters:
  • period – Type: long, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0

Sets the period 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 value has changed since the last triggering.

long BrickletRotaryPoti.getAnalogValueCallbackPeriod()
Returns:
  • period – Type: long, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0

Returns the period as set by setAnalogValueCallbackPeriod().

void BrickletRotaryPoti.setPositionCallbackThreshold(char option, short min, short max)
Parameters:
  • option – Type: char, Range: See constants, Default: 'x'
  • min – Type: short, Unit: 1 °, Range: [-215 to 215 - 1], Default: 0
  • max – Type: short, Unit: 1 °, Range: [-215 to 215 - 1], Default: 0

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 value (max is ignored)
'>' Listener is triggered when the position is greater than the min value (max is ignored)

The following constants are available for this function:

For option:

  • BrickletRotaryPoti.THRESHOLD_OPTION_OFF = 'x'
  • BrickletRotaryPoti.THRESHOLD_OPTION_OUTSIDE = 'o'
  • BrickletRotaryPoti.THRESHOLD_OPTION_INSIDE = 'i'
  • BrickletRotaryPoti.THRESHOLD_OPTION_SMALLER = '<'
  • BrickletRotaryPoti.THRESHOLD_OPTION_GREATER = '>'
BrickletRotaryPoti.PositionCallbackThreshold BrickletRotaryPoti.getPositionCallbackThreshold()
Return Object:
  • option – Type: char, Range: See constants, Default: 'x'
  • min – Type: short, Unit: 1 °, Range: [-215 to 215 - 1], Default: 0
  • max – Type: short, Unit: 1 °, Range: [-215 to 215 - 1], Default: 0

Returns the threshold as set by setPositionCallbackThreshold().

The following constants are available for this function:

For option:

  • BrickletRotaryPoti.THRESHOLD_OPTION_OFF = 'x'
  • BrickletRotaryPoti.THRESHOLD_OPTION_OUTSIDE = 'o'
  • BrickletRotaryPoti.THRESHOLD_OPTION_INSIDE = 'i'
  • BrickletRotaryPoti.THRESHOLD_OPTION_SMALLER = '<'
  • BrickletRotaryPoti.THRESHOLD_OPTION_GREATER = '>'
void BrickletRotaryPoti.setAnalogValueCallbackThreshold(char option, int min, int max)
Parameters:
  • option – Type: char, Range: See constants, Default: 'x'
  • min – Type: int, Unit: 1 °, Range: [0 to 216 - 1], Default: 0
  • max – Type: int, Unit: 1 °, Range: [0 to 216 - 1], Default: 0

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 value is outside the min and max values
'i' Listener is triggered when the analog value is inside the min and max values
'<' Listener is triggered when the analog value is smaller than the min value (max is ignored)
'>' Listener is triggered when the analog value is greater than the min value (max is ignored)

The following constants are available for this function:

For option:

  • BrickletRotaryPoti.THRESHOLD_OPTION_OFF = 'x'
  • BrickletRotaryPoti.THRESHOLD_OPTION_OUTSIDE = 'o'
  • BrickletRotaryPoti.THRESHOLD_OPTION_INSIDE = 'i'
  • BrickletRotaryPoti.THRESHOLD_OPTION_SMALLER = '<'
  • BrickletRotaryPoti.THRESHOLD_OPTION_GREATER = '>'
BrickletRotaryPoti.AnalogValueCallbackThreshold BrickletRotaryPoti.getAnalogValueCallbackThreshold()
Return Object:
  • option – Type: char, Range: See constants, Default: 'x'
  • min – Type: int, Unit: 1 °, Range: [0 to 216 - 1], Default: 0
  • max – Type: int, Unit: 1 °, Range: [0 to 216 - 1], Default: 0

Returns the threshold as set by setAnalogValueCallbackThreshold().

The following constants are available for this function:

For option:

  • BrickletRotaryPoti.THRESHOLD_OPTION_OFF = 'x'
  • BrickletRotaryPoti.THRESHOLD_OPTION_OUTSIDE = 'o'
  • BrickletRotaryPoti.THRESHOLD_OPTION_INSIDE = 'i'
  • BrickletRotaryPoti.THRESHOLD_OPTION_SMALLER = '<'
  • BrickletRotaryPoti.THRESHOLD_OPTION_GREATER = '>'
void BrickletRotaryPoti.setDebouncePeriod(long debounce)
Parameters:
  • debounce – Type: long, Unit: 1 ms, Range: [0 to 232 - 1], Default: 100

Sets the period with which the threshold listeners

are triggered, if the thresholds

keep being reached.

long BrickletRotaryPoti.getDebouncePeriod()
Returns:
  • debounce – Type: long, Unit: 1 ms, Range: [0 to 232 - 1], Default: 100

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 BrickletRotaryPoti.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.

class BrickletRotaryPoti.PositionListener()

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

void position(short position)
Parameters:
  • position – Type: short, Unit: 1 °, Range: [-150 to 150]

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

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

class BrickletRotaryPoti.AnalogValueListener()

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

void analogValue(int value)
Parameters:
  • value – Type: int, Range: [0 to 4096]

This listener is triggered periodically with the period that is set by setAnalogValueCallbackPeriod(). The parameter is the analog value of the rotary potentiometer.

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

class BrickletRotaryPoti.PositionReachedListener()

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

void positionReached(short position)
Parameters:
  • position – Type: short, Unit: 1 °, Range: [-150 to 150]

This listener is triggered when the threshold as set by setPositionCallbackThreshold() is reached. The parameter is the position of the rotary potentiometer.

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

class BrickletRotaryPoti.AnalogValueReachedListener()

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

void analogValueReached(int value)
Parameters:
  • value – Type: int, Range: [0 to 4096]

This listener is triggered when the threshold as set by setAnalogValueCallbackThreshold() is reached. The parameter is the analog value of the rotary potentiometer.

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

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.

short[] BrickletRotaryPoti.getAPIVersion()
Return Object:
  • apiVersion – Type: short[], Length: 3
    • 0: major – Type: short, Range: [0 to 255]
    • 1: minor – Type: short, Range: [0 to 255]
    • 2: revision – Type: short, 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.

boolean BrickletRotaryPoti.getResponseExpected(short functionId)
Parameters:
  • functionId – Type: short, 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 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.

The following constants are available for this function:

For functionId:

  • BrickletRotaryPoti.FUNCTION_SET_POSITION_CALLBACK_PERIOD = 3
  • BrickletRotaryPoti.FUNCTION_SET_ANALOG_VALUE_CALLBACK_PERIOD = 5
  • BrickletRotaryPoti.FUNCTION_SET_POSITION_CALLBACK_THRESHOLD = 7
  • BrickletRotaryPoti.FUNCTION_SET_ANALOG_VALUE_CALLBACK_THRESHOLD = 9
  • BrickletRotaryPoti.FUNCTION_SET_DEBOUNCE_PERIOD = 11
void BrickletRotaryPoti.setResponseExpected(short functionId, boolean responseExpected)
Parameters:
  • functionId – Type: short, 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 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 constants are available for this function:

For functionId:

  • BrickletRotaryPoti.FUNCTION_SET_POSITION_CALLBACK_PERIOD = 3
  • BrickletRotaryPoti.FUNCTION_SET_ANALOG_VALUE_CALLBACK_PERIOD = 5
  • BrickletRotaryPoti.FUNCTION_SET_POSITION_CALLBACK_THRESHOLD = 7
  • BrickletRotaryPoti.FUNCTION_SET_ANALOG_VALUE_CALLBACK_THRESHOLD = 9
  • BrickletRotaryPoti.FUNCTION_SET_DEBOUNCE_PERIOD = 11
void BrickletRotaryPoti.setResponseExpectedAll(boolean responseExpected)
Parameters:
  • responseExpected – Type: boolean

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

Constants

int BrickletRotaryPoti.DEVICE_IDENTIFIER

This constant is used to identify a Rotary Poti Bricklet.

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

String BrickletRotaryPoti.DEVICE_DISPLAY_NAME

This constant represents the human readable name of a Rotary Poti Bricklet.