Visual Basic .NET - GPS Bricklet

This is the description of the Visual Basic .NET 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 Visual Basic .NET API bindings is part of their general description.

Examples

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

Simple

Download (ExampleSimple.vb)

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Imports System
Imports Tinkerforge

Module ExampleSimple
    Const HOST As String = "localhost"
    Const PORT As Integer = 4223
    Const UID As String = "XYZ" ' Change XYZ to the UID of your GPS Bricklet

    Sub Main()
        Dim ipcon As New IPConnection() ' Create IP connection
        Dim gps As 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
        Dim latitude, longitude As Long
        Dim ns, ew As Char
        Dim pdop, hdop, vdop, epe As Integer

        gps.GetCoordinates(latitude, ns, longitude, ew, pdop, hdop, vdop, epe)

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

        Console.WriteLine("Press key to exit")
        Console.ReadLine()
        ipcon.Disconnect()
    End Sub
End Module

Callback

Download (ExampleCallback.vb)

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Imports System
Imports Tinkerforge

Module ExampleCallback
    Const HOST As String = "localhost"
    Const PORT As Integer = 4223
    Const UID As String = "XYZ" ' Change XYZ to the UID of your GPS Bricklet

    ' Callback subroutine for coordinates callback
    Sub CoordinatesCB(ByVal sender As BrickletGPS, ByVal latitude As Long, _
                      ByVal ns As Char, ByVal longitude As Long, ByVal ew As Char, _
                      ByVal pdop As Integer, ByVal hdop As Integer, _
                      ByVal vdop As Integer, ByVal epe As Integer)
        Console.WriteLine("Latitude: " + (latitude/1000000.0).ToString() + " °")
        Console.WriteLine("N/S: " + ns)
        Console.WriteLine("Longitude: " + (longitude/1000000.0).ToString() + " °")
        Console.WriteLine("E/W: " + ew)
        Console.WriteLine("")
    End Sub

    Sub Main()
        Dim ipcon As New IPConnection() ' Create IP connection
        Dim gps As 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 subroutine CoordinatesCB
        AddHandler gps.CoordinatesCallback, AddressOf 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 key to exit")
        Console.ReadLine()
        ipcon.Disconnect()
    End Sub
End Module

API

Since Visual Basic .NET does not support multiple return values directly, we use the ByRef keyword to return multiple values from a function.

All functions and procedures listed below are thread-safe.

Basic Functions

Class BrickletGPS(ByVal uid As String, ByVal ipcon As IPConnection)

Creates an object with the unique device ID uid:

Dim gps As New BrickletGPS("YOUR_DEVICE_UID", ipcon)

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

Sub BrickletGPS.GetCoordinates(ByRef latitude As Long, ByRef ns As Char, ByRef longitude As Long, ByRef ew As Char, ByRef pdop As Integer, ByRef hdop As Integer, ByRef vdop As Integer, ByRef epe As Integer)
Output Parameters:
  • latitude – Type: Long, Range: [0 to 232 - 1]
  • ns – Type: Char
  • longitude – Type: Long, Range: [0 to 232 - 1]
  • ew – Type: Char
  • pdop – Type: Integer, Range: [0 to 216 - 1]
  • hdop – Type: Integer, Range: [0 to 216 - 1]
  • vdop – Type: Integer, Range: [0 to 216 - 1]
  • epe – Type: Integer, 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. 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().

Sub BrickletGPS.GetStatus(ByRef fix As Byte, ByRef satellitesView As Byte, ByRef satellitesUsed As Byte)
Output Parameters:
  • fix – Type: Byte, Range: See constants
  • satellitesView – Type: Byte, Range: [0 to 255]
  • satellitesUsed – Type: Byte, 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
Sub BrickletGPS.GetAltitude(ByRef altitude As Integer, ByRef geoidalSeparation As Integer)
Output Parameters:
  • altitude – Type: Integer, Range: [-231 to 231 - 1]
  • geoidalSeparation – Type: Integer, Range: [-231 to 231 - 1]

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().

Sub BrickletGPS.GetMotion(ByRef course As Long, ByRef speed As Long)
Output Parameters:
  • course – Type: Long, Range: [0 to 232 - 1]
  • speed – Type: Long, Range: [0 to 232 - 1]

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().

Sub BrickletGPS.GetDateTime(ByRef date As Long, ByRef time As Long)
Output Parameters:
  • date – Type: Long, Range: [0 to 232 - 1]
  • time – Type: Long, Range: [0 to 232 - 1]

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

Sub BrickletGPS.Restart(ByVal restartType As Byte)
Parameters:
  • restartType – Type: Byte, 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
Function BrickletGPS.GetAPIVersion() As Byte()
Returns:
  • apiVersion – Type: Byte Array, Length: 3, Range: [0 to 255]

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.

Function BrickletGPS.GetResponseExpected(ByVal functionId As Byte) As Boolean
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 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.

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
Sub BrickletGPS.SetResponseExpected(ByVal functionId As Byte, ByVal responseExpected As Boolean)
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 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 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
Sub BrickletGPS.SetResponseExpectedAll(ByVal responseExpected As Boolean)
Parameters:
  • responseExpected – Type: Boolean

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

Sub BrickletGPS.GetIdentity(ByRef uid As String, ByRef connectedUid As String, ByRef position As Char, ByRef hardwareVersion() As Byte, ByRef firmwareVersion() As Byte, ByRef deviceIdentifier As Integer)
Output Parameters:
  • uid – Type: String, Length: up to 8
  • connectedUid – Type: String, Length: up to 8
  • position – Type: Char
  • hardwareVersion – Type: Byte Array, Length: 3, Range: [0 to 255]
  • firmwareVersion – Type: Byte Array, Length: 3, Range: [0 to 255]
  • deviceIdentifier – Type: Integer, 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' 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

Sub BrickletGPS.SetCoordinatesCallbackPeriod(ByVal period As Long)
Parameters:
  • period – Type: Long, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0

Sets the period 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.

Function BrickletGPS.GetCoordinatesCallbackPeriod() As Long
Returns:
  • period – Type: Long, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0

Returns the period as set by SetCoordinatesCallbackPeriod().

Sub BrickletGPS.SetStatusCallbackPeriod(ByVal period As Long)
Parameters:
  • period – Type: Long, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0

Sets the period 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.

Function BrickletGPS.GetStatusCallbackPeriod() As Long
Returns:
  • period – Type: Long, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0

Returns the period as set by SetStatusCallbackPeriod().

Sub BrickletGPS.SetAltitudeCallbackPeriod(ByVal period As Long)
Parameters:
  • period – Type: Long, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0

Sets the period 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.

Function BrickletGPS.GetAltitudeCallbackPeriod() As Long
Returns:
  • period – Type: Long, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0

Returns the period as set by SetAltitudeCallbackPeriod().

Sub BrickletGPS.SetMotionCallbackPeriod(ByVal period As Long)
Parameters:
  • period – Type: Long, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0

Sets the period 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.

Function BrickletGPS.GetMotionCallbackPeriod() As Long
Returns:
  • period – Type: Long, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0

Returns the period as set by SetMotionCallbackPeriod().

Sub BrickletGPS.SetDateTimeCallbackPeriod(ByVal period As Long)
Parameters:
  • period – Type: Long, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0

Sets the period 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.

Function BrickletGPS.GetDateTimeCallbackPeriod() As Long
Returns:
  • period – Type: Long, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0

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 assigning a procedure to an callback property of the device object:

Sub MyCallback(ByVal sender As BrickletGPS, ByVal value As Short)
    Console.WriteLine("Value: {0}", value)
End Sub

AddHandler gps.ExampleCallback, AddressOf MyCallback

The available callback property and their type of parameters 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.

Event BrickletGPS.CoordinatesCallback(ByVal sender As BrickletGPS, ByVal latitude As Long, ByVal ns As Char, ByVal longitude As Long, ByVal ew As Char, ByVal pdop As Integer, ByVal hdop As Integer, ByVal vdop As Integer, ByVal epe As Integer)
Callback Parameters:
  • sender – Type: BrickletGPS
  • latitude – Type: Long, Range: [0 to 232 - 1]
  • ns – Type: Char
  • longitude – Type: Long, Range: [0 to 232 - 1]
  • ew – Type: Char
  • pdop – Type: Integer, Range: [0 to 216 - 1]
  • hdop – Type: Integer, Range: [0 to 216 - 1]
  • vdop – Type: Integer, Range: [0 to 216 - 1]
  • epe – Type: Integer, Range: [0 to 216 - 1]

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().

Event BrickletGPS.StatusCallback(ByVal sender As BrickletGPS, ByVal fix As Byte, ByVal satellitesView As Byte, ByVal satellitesUsed As Byte)
Callback Parameters:
  • sender – Type: BrickletGPS
  • fix – Type: Byte, Range: See constants
  • satellitesView – Type: Byte, Range: [0 to 255]
  • satellitesUsed – Type: Byte, Range: [0 to 255]

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:

For fix:

  • BrickletGPS.FIX_NO_FIX = 1
  • BrickletGPS.FIX_2D_FIX = 2
  • BrickletGPS.FIX_3D_FIX = 3
Event BrickletGPS.AltitudeCallback(ByVal sender As BrickletGPS, ByVal altitude As Integer, ByVal geoidalSeparation As Integer)
Callback Parameters:
  • sender – Type: BrickletGPS
  • altitude – Type: Integer, Range: [-231 to 231 - 1]
  • geoidalSeparation – Type: Integer, Range: [-231 to 231 - 1]

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().

Event BrickletGPS.MotionCallback(ByVal sender As BrickletGPS, ByVal course As Long, ByVal speed As Long)
Callback Parameters:
  • sender – Type: BrickletGPS
  • course – Type: Long, Range: [0 to 232 - 1]
  • speed – Type: Long, Range: [0 to 232 - 1]

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().

Event BrickletGPS.DateTimeCallback(ByVal sender As BrickletGPS, ByVal date As Long, ByVal time As Long)
Callback Parameters:
  • sender – Type: BrickletGPS
  • date – Type: Long, Range: [0 to 232 - 1]
  • time – Type: Long, Range: [0 to 232 - 1]

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

Const BrickletGPS.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.

Const BrickletGPS.DEVICE_DISPLAY_NAME

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