Java - GPS Bricklet

This is the description of the Java API bindings for the GPS Bricklet. General information and technical specifications for the GPS 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.BrickletGPS;
import com.tinkerforge.BrickletGPS.Coordinates;

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

    // Change XYZ to the UID of your GPS 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
        BrickletGPS gps = new BrickletGPS(UID, ipcon); // Create device object

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

        // Get current coordinates
        Coordinates coordinates = gps.getCoordinates(); // Can throw com.tinkerforge.TimeoutException

        System.out.println("Latitude: " + coordinates.latitude/1000000.0 + " °");
        System.out.println("N/S: " + coordinates.ns);
        System.out.println("Longitude: " + coordinates.longitude/1000000.0 + " °");
        System.out.println("E/W: " + coordinates.ew);

        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.BrickletGPS;

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

    // Change XYZ to the UID of your GPS 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
        BrickletGPS gps = new BrickletGPS(UID, ipcon); // Create device object

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

        // Add coordinates listener
        gps.addCoordinatesListener(new BrickletGPS.CoordinatesListener() {
            public void coordinates(long latitude, char ns, long longitude, char ew,
                                    int pdop, int hdop, int vdop, int epe) {
                System.out.println("Latitude: " + latitude/1000000.0 + " °");
                System.out.println("N/S: " + ns);
                System.out.println("Longitude: " + longitude/1000000.0 + " °");
                System.out.println("E/W: " + ew);
                System.out.println("");
            }
        });

        // Set period for coordinates callback to 1s (1000ms)
        // Note: The coordinates callback is only called every second
        //       if the coordinates has changed since the last call!
        gps.setCoordinatesCallbackPeriod(1000);

        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 BrickletGPS(String uid, IPConnection ipcon)
Parameters:
  • uid – Type: String
  • ipcon – Type: IPConnection
Returns:
  • gps – Type: BrickletGPS

Creates an object with the unique device ID uid:

BrickletGPS gps = new BrickletGPS("YOUR_DEVICE_UID", ipcon);

This object can then be used after the IP Connection is connected.

BrickletGPS.Coordinates BrickletGPS.getCoordinates()
Return Object:
  • latitude – Type: long, Unit: 1/1000000 °, Range: [0 to 90000000]
  • ns – Type: char, Range: ['N', 'S']
  • longitude – Type: long, Unit: 1/1000000 °, Range: [0 to 180000000]
  • ew – Type: char, Range: ['E', 'W']
  • pdop – Type: int, Unit: 1/100, Range: [0 to 216 - 1]
  • hdop – Type: int, Unit: 1/100, Range: [0 to 216 - 1]
  • vdop – Type: int, Unit: 1/100, Range: [0 to 216 - 1]
  • epe – Type: int, Unit: 1 cm, Range: [0 to 216 - 1]

Returns the GPS coordinates. Latitude and longitude are given in the DD.dddddd° format, the value 57123468 means 57.123468°. The parameter ns and ew are the cardinal directions for latitude and longitude. Possible values for ns and ew are 'N', 'S', 'E' and 'W' (north, south, east and west).

PDOP, HDOP and VDOP are the dilution of precision (DOP) values. They specify the additional multiplicative effect of GPS satellite geometry on GPS precision. See here for more information.

EPE is the "Estimated Position Error". This is not the absolute maximum error, it is the error with a specific confidence. See here for more information.

This data is only valid if there is currently a fix as indicated by getStatus().

BrickletGPS.Status BrickletGPS.getStatus()
Return Object:
  • fix – Type: short, Range: See constants
  • satellitesView – Type: short, Range: [0 to 255]
  • satellitesUsed – Type: short, Range: [0 to 255]

Returns the current fix status, the number of satellites that are in view and the number of satellites that are currently used.

Possible fix status values can be:

Value Description
1 No Fix, getCoordinates(), getAltitude() and getMotion() return invalid data
2 2D Fix, only getCoordinates() and getMotion() return valid data
3 3D Fix, getCoordinates(), getAltitude() and getMotion() return valid data

There is also a blue LED on the Bricklet that indicates the fix status.

The following constants are available for this function:

For fix:

  • BrickletGPS.FIX_NO_FIX = 1
  • BrickletGPS.FIX_2D_FIX = 2
  • BrickletGPS.FIX_3D_FIX = 3
BrickletGPS.Altitude BrickletGPS.getAltitude()
Return Object:
  • altitude – Type: int, Unit: 1 cm, Range: [-231 to 231 - 1]
  • geoidalSeparation – Type: int, Unit: 1 cm, Range: [-231 to 231 - 1]

Returns the current altitude and corresponding geoidal separation.

This data is only valid if there is currently a fix as indicated by getStatus().

BrickletGPS.Motion BrickletGPS.getMotion()
Return Object:
  • course – Type: long, Unit: 1/100 °, Range: [0 to 36000]
  • speed – Type: long, Unit: 1/100 km/h, Range: [0 to 232 - 1]

Returns the current course and speed. A course of 0° means the Bricklet is traveling north bound and 90° means it is traveling east bound.

Please note that this only returns useful values if an actual movement is present.

This data is only valid if there is currently a fix as indicated by getStatus().

BrickletGPS.DateTime BrickletGPS.getDateTime()
Return Object:
  • date – Type: long, Range: [10100 to 311299]
  • time – Type: long, Range: [0 to 235959999]

Returns the current date and time. The date is given in the format ddmmyy and the time is given in the format hhmmss.sss. For example, 140713 means 14.07.13 as date and 195923568 means 19:59:23.568 as time.

Advanced Functions

void BrickletGPS.restart(short restartType)
Parameters:
  • restartType – Type: short, Range: See constants

Restarts the GPS Bricklet, the following restart types are available:

Value Description
0 Hot start (use all available data in the NV store)
1 Warm start (don't use ephemeris at restart)
2 Cold start (don't use time, position, almanacs and ephemeris at restart)
3 Factory reset (clear all system/user configurations at restart)

The following constants are available for this function:

For restartType:

  • BrickletGPS.RESTART_TYPE_HOT_START = 0
  • BrickletGPS.RESTART_TYPE_WARM_START = 1
  • BrickletGPS.RESTART_TYPE_COLD_START = 2
  • BrickletGPS.RESTART_TYPE_FACTORY_RESET = 3
BrickletGPS.Identity BrickletGPS.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 BrickletGPS.setCoordinatesCallbackPeriod(long period)
Parameters:
  • period – Type: long, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0

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

The CoordinatesListener listener is only triggered if the coordinates changed since the last triggering.

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

Returns the period as set by setCoordinatesCallbackPeriod().

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

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

The StatusListener listener is only triggered if the status changed since the last triggering.

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

Returns the period as set by setStatusCallbackPeriod().

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

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

The AltitudeListener listener is only triggered if the altitude changed since the last triggering.

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

Returns the period as set by setAltitudeCallbackPeriod().

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

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

The MotionListener listener is only triggered if the motion changed since the last triggering.

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

Returns the period as set by setMotionCallbackPeriod().

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

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

The DateTimeListener listener is only triggered if the date or time changed since the last triggering.

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

Returns the period as set by setDateTimeCallbackPeriod().

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 BrickletGPS.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 BrickletGPS.CoordinatesListener()

This listener can be added with the addCoordinatesListener() function. An added listener can be removed with the removeCoordinatesListener() function.

void coordinates(long latitude, char ns, long longitude, char ew, int pdop, int hdop, int vdop, int epe)
Parameters:
  • latitude – Type: long, Unit: 1/1000000 °, Range: [0 to 90000000]
  • ns – Type: char, Range: ['N', 'S']
  • longitude – Type: long, Unit: 1/1000000 °, Range: [0 to 180000000]
  • ew – Type: char, Range: ['E', 'W']
  • pdop – Type: int, Unit: 1/100, Range: [0 to 216 - 1]
  • hdop – Type: int, Unit: 1/100, Range: [0 to 216 - 1]
  • vdop – Type: int, Unit: 1/100, Range: [0 to 216 - 1]
  • epe – Type: int, Unit: 1 cm, Range: [0 to 216 - 1]

This listener is triggered periodically with the period that is set by setCoordinatesCallbackPeriod(). The parameters are the same as for getCoordinates().

The CoordinatesListener listener is only triggered if the coordinates changed since the last triggering and if there is currently a fix as indicated by getStatus().

class BrickletGPS.StatusListener()

This listener can be added with the addStatusListener() function. An added listener can be removed with the removeStatusListener() function.

void status(short fix, short satellitesView, short satellitesUsed)
Parameters:
  • fix – Type: short, Range: See constants
  • satellitesView – Type: short, Range: [0 to 255]
  • satellitesUsed – Type: short, Range: [0 to 255]

This listener is triggered periodically with the period that is set by setStatusCallbackPeriod(). The parameters are the same as for getStatus().

The StatusListener listener is only triggered if the status changed since the last triggering.

The following constants are available for this function:

For fix:

  • BrickletGPS.FIX_NO_FIX = 1
  • BrickletGPS.FIX_2D_FIX = 2
  • BrickletGPS.FIX_3D_FIX = 3
class BrickletGPS.AltitudeListener()

This listener can be added with the addAltitudeListener() function. An added listener can be removed with the removeAltitudeListener() function.

void altitude(int altitude, int geoidalSeparation)
Parameters:
  • altitude – Type: int, Unit: 1 cm, Range: [-231 to 231 - 1]
  • geoidalSeparation – Type: int, Unit: 1 cm, Range: [-231 to 231 - 1]

This listener is triggered periodically with the period that is set by setAltitudeCallbackPeriod(). The parameters are the same as for getAltitude().

The AltitudeListener listener is only triggered if the altitude changed since the last triggering and if there is currently a fix as indicated by getStatus().

class BrickletGPS.MotionListener()

This listener can be added with the addMotionListener() function. An added listener can be removed with the removeMotionListener() function.

void motion(long course, long speed)
Parameters:
  • course – Type: long, Unit: 1/100 °, Range: [0 to 36000]
  • speed – Type: long, Unit: 1/100 km/h, Range: [0 to 232 - 1]

This listener is triggered periodically with the period that is set by setMotionCallbackPeriod(). The parameters are the same as for getMotion().

The MotionListener listener is only triggered if the motion changed since the last triggering and if there is currently a fix as indicated by getStatus().

class BrickletGPS.DateTimeListener()

This listener can be added with the addDateTimeListener() function. An added listener can be removed with the removeDateTimeListener() function.

void dateTime(long date, long time)
Parameters:
  • date – Type: long, Range: [10100 to 311299]
  • time – Type: long, Range: [0 to 235959999]

This listener is triggered periodically with the period that is set by setDateTimeCallbackPeriod(). The parameters are the same as for getDateTime().

The DateTimeListener listener is only triggered if the date or time changed since the last triggering.

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[] BrickletGPS.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 BrickletGPS.getResponseExpected(byte functionId)
Parameters:
  • functionId – Type: byte, 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 sent and errors are silently ignored, because they cannot be detected.

The following constants are available for this function:

For functionId:

  • BrickletGPS.FUNCTION_RESTART = 6
  • BrickletGPS.FUNCTION_SET_COORDINATES_CALLBACK_PERIOD = 7
  • BrickletGPS.FUNCTION_SET_STATUS_CALLBACK_PERIOD = 9
  • BrickletGPS.FUNCTION_SET_ALTITUDE_CALLBACK_PERIOD = 11
  • BrickletGPS.FUNCTION_SET_MOTION_CALLBACK_PERIOD = 13
  • BrickletGPS.FUNCTION_SET_DATE_TIME_CALLBACK_PERIOD = 15
void BrickletGPS.setResponseExpected(byte functionId, boolean responseExpected)
Parameters:
  • functionId – Type: byte, 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 sent and errors are silently ignored, because they cannot be detected.

The following constants are available for this function:

For functionId:

  • BrickletGPS.FUNCTION_RESTART = 6
  • BrickletGPS.FUNCTION_SET_COORDINATES_CALLBACK_PERIOD = 7
  • BrickletGPS.FUNCTION_SET_STATUS_CALLBACK_PERIOD = 9
  • BrickletGPS.FUNCTION_SET_ALTITUDE_CALLBACK_PERIOD = 11
  • BrickletGPS.FUNCTION_SET_MOTION_CALLBACK_PERIOD = 13
  • BrickletGPS.FUNCTION_SET_DATE_TIME_CALLBACK_PERIOD = 15
void BrickletGPS.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 BrickletGPS.DEVICE_IDENTIFIER

This constant is used to identify a GPS 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 BrickletGPS.DEVICE_DISPLAY_NAME

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