C# - GPS Bricklet

This is the description of the C# 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 C# API bindings is part of their general description.

Examples

The example code below is Public Domain (CC0 1.0).

Simple

Download (ExampleSimple.cs)

 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
using System;
using Tinkerforge;

class Example
{
    private static string HOST = "localhost";
    private static int PORT = 4223;
    private static string UID = "XYZ"; // Change XYZ to the UID of your GPS Bricklet

    static void Main()
    {
        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
        long latitude, longitude; char ns, ew; int pdop, hdop, vdop, epe;
        gps.GetCoordinates(out latitude, out ns, out longitude, out ew, out pdop,
                           out hdop, out vdop, out epe);

        Console.WriteLine("Latitude: " + latitude/1000000.0 + " °");
        Console.WriteLine("N/S: " + ns);
        Console.WriteLine("Longitude: " + longitude/1000000.0 + " °");
        Console.WriteLine("E/W: " + ew);

        Console.WriteLine("Press enter to exit");
        Console.ReadLine();
        ipcon.Disconnect();
    }
}

Callback

Download (ExampleCallback.cs)

 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
using System;
using Tinkerforge;

class Example
{
    private static string HOST = "localhost";
    private static int PORT = 4223;
    private static string UID = "XYZ"; // Change XYZ to the UID of your GPS Bricklet

    // Callback function for coordinates callback
    static void CoordinatesCB(BrickletGPS sender, long latitude, char ns, long longitude,
                              char ew, int pdop, int hdop, int vdop, int epe)
    {
        Console.WriteLine("Latitude: " + latitude/1000000.0 + " °");
        Console.WriteLine("N/S: " + ns);
        Console.WriteLine("Longitude: " + longitude/1000000.0 + " °");
        Console.WriteLine("E/W: " + ew);
        Console.WriteLine("");
    }

    static void Main()
    {
        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

        // Register coordinates callback to function CoordinatesCB
        gps.CoordinatesCallback += CoordinatesCB;

        // 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);

        Console.WriteLine("Press enter to exit");
        Console.ReadLine();
        ipcon.Disconnect();
    }
}

API

Generally, every method of the C# bindings that returns a value can throw a Tinkerforge.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 plugs the device out). However, if a wireless connection is used, timeouts will occur if the distance to the device gets too big.

Since C# does not support multiple return values directly, we use the out keyword to return multiple values from a method.

The namespace for all Brick/Bricklet bindings and the IPConnection is Tinkerforge.*.

All methods listed below are thread-safe.

Basic Functions

public class BrickletGPS(String uid, IPConnection ipcon)

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 (see examples above).

public void GetCoordinates(out long latitude, out char ns, out long longitude, out char ew, out int pdop, out int hdop, out int vdop, out int epe)

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. The values are give in hundredths.

EPE is the "Estimated Position Error". The EPE is given in cm. 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().

public void GetStatus(out byte fix, out byte satellitesView, out byte satellitesUsed)

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:

  • BrickletGPS.FIX_NO_FIX = 1
  • BrickletGPS.FIX_2D_FIX = 2
  • BrickletGPS.FIX_3D_FIX = 3
public void GetAltitude(out int altitude, out int geoidalSeparation)

Returns the current altitude and corresponding geoidal separation.

Both values are given in cm.

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

public void GetMotion(out long course, out long speed)

Returns the current course and speed. Course is given in hundredths degree and speed is given in hundredths km/h. 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().

public void GetDateTime(out long date, out long time)

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 14.05.13 as date and 195923568 means 19:59:23.568 as time.

Advanced Functions

public void Restart(byte restartType)

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:

  • BrickletGPS.RESTART_TYPE_HOT_START = 0
  • BrickletGPS.RESTART_TYPE_WARM_START = 1
  • BrickletGPS.RESTART_TYPE_COLD_START = 2
  • BrickletGPS.RESTART_TYPE_FACTORY_RESET = 3
public byte[] 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 bool GetResponseExpected(byte 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 callback 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(byte functionId, bool 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 callback 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:

  • 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
public void SetResponseExpectedAll(bool responseExpected)

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

public void GetIdentity(out string uid, out string connectedUid, out char position, out byte[] hardwareVersion, out byte[] firmwareVersion, out int deviceIdentifier)

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.

Callback Configuration Functions

public void SetCoordinatesCallbackPeriod(long period)

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

The CoordinatesCallback callback is only triggered if the coordinates changed since the last triggering.

The default value is 0.

public long GetCoordinatesCallbackPeriod()

Returns the period as set by SetCoordinatesCallbackPeriod().

public void SetStatusCallbackPeriod(long period)

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

The StatusCallback callback is only triggered if the status changed since the last triggering.

The default value is 0.

public long GetStatusCallbackPeriod()

Returns the period as set by SetStatusCallbackPeriod().

public void SetAltitudeCallbackPeriod(long period)

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

The AltitudeCallback callback is only triggered if the altitude changed since the last triggering.

The default value is 0.

public long GetAltitudeCallbackPeriod()

Returns the period as set by SetAltitudeCallbackPeriod().

public void SetMotionCallbackPeriod(long period)

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

The MotionCallback callback is only triggered if the motion changed since the last triggering.

The default value is 0.

public long GetMotionCallbackPeriod()

Returns the period as set by SetMotionCallbackPeriod().

public void SetDateTimeCallbackPeriod(long period)

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

The DateTimeCallback callback is only triggered if the date or time changed since the last triggering.

The default value is 0.

public long GetDateTimeCallbackPeriod()

Returns the period as set by SetDateTimeCallbackPeriod().

Callbacks

Callbacks can be registered to receive time critical or recurring data from the device. The registration is done by appending your callback handler to the corresponding event:

void MyCallback(BrickletGPS sender, int value)
{
    System.Console.WriteLine("Value: " + value);
}

gps.ExampleCallback += MyCallback;

The available events are described below.

Note

Using callbacks 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 event CoordinatesCallback(BrickletGPS sender, long latitude, char ns, long longitude, char ew, int pdop, int hdop, int vdop, int epe)

This callback is triggered periodically with the period that is set by SetCoordinatesCallbackPeriod(). The parameters are the same as for GetCoordinates().

The CoordinatesCallback callback is only triggered if the coordinates changed since the last triggering and if there is currently a fix as indicated by GetStatus().

public event StatusCallback(BrickletGPS sender, byte fix, byte satellitesView, byte satellitesUsed)

This callback is triggered periodically with the period that is set by SetStatusCallbackPeriod(). The parameters are the same as for GetStatus().

The StatusCallback callback is only triggered if the status changed since the last triggering.

The following constants are available for this function:

  • BrickletGPS.FIX_NO_FIX = 1
  • BrickletGPS.FIX_2D_FIX = 2
  • BrickletGPS.FIX_3D_FIX = 3
public event AltitudeCallback(BrickletGPS sender, int altitude, int geoidalSeparation)

This callback is triggered periodically with the period that is set by SetAltitudeCallbackPeriod(). The parameters are the same as for GetAltitude().

The AltitudeCallback callback is only triggered if the altitude changed since the last triggering and if there is currently a fix as indicated by GetStatus().

public event MotionCallback(BrickletGPS sender, long course, long speed)

This callback is triggered periodically with the period that is set by SetMotionCallbackPeriod(). The parameters are the same as for GetMotion().

The MotionCallback callback is only triggered if the motion changed since the last triggering and if there is currently a fix as indicated by GetStatus().

public event DateTimeCallback(BrickletGPS sender, long date, long time)

This callback is triggered periodically with the period that is set by SetDateTimeCallbackPeriod(). The parameters are the same as for GetDateTime().

The DateTimeCallback callback is only triggered if the date or time changed since the last triggering.

Constants

public int DEVICE_IDENTIFIER

This constant is used to identify a GPS Bricklet.

The GetIdentity() function and the IPConnection.EnumerateCallback callback of the IP Connection have a deviceIdentifier parameter to specify the Brick's or Bricklet's type.

public string DEVICE_DISPLAY_NAME

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