Perl - GPS Bricklet

This is the description of the Perl 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 Perl API bindings is part of their general description.

Examples

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

Simple

Download (example_simple.pl)

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#!/usr/bin/perl

use strict;
use Tinkerforge::IPConnection;
use Tinkerforge::BrickletGPS;

use constant HOST => 'localhost';
use constant PORT => 4223;
use constant UID => 'XYZ'; # Change XYZ to the UID of your GPS Bricklet

my $ipcon = Tinkerforge::IPConnection->new(); # Create IP connection
my $gps = Tinkerforge::BrickletGPS->new(&UID, $ipcon); # Create device object

$ipcon->connect(&HOST, &PORT); # Connect to brickd
# Don't use device before ipcon is connected

# Get current coordinates
my ($latitude, $ns, $longitude, $ew, $pdop, $hdop, $vdop, $epe) = $gps->get_coordinates();

print "Latitude: " . $latitude/1000000.0 . " °\n";
print "N/S: $ns\n";
print "Longitude: " . $longitude/1000000.0 . " °\n";
print "E/W: $ew\n";

print "Press key to exit\n";
<STDIN>;
$ipcon->disconnect();

Callback

Download (example_callback.pl)

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#!/usr/bin/perl

use strict;
use Tinkerforge::IPConnection;
use Tinkerforge::BrickletGPS;

use constant HOST => 'localhost';
use constant PORT => 4223;
use constant UID => 'XYZ'; # Change XYZ to the UID of your GPS Bricklet

# Callback subroutine for coordinates callback
sub cb_coordinates
{
    my ($latitude, $ns, $longitude, $ew, $pdop, $hdop, $vdop, $epe) = @_;

    print "Latitude: " . $latitude/1000000.0 . " °\n";
    print "N/S: $ns\n";
    print "Longitude: " . $longitude/1000000.0 . " °\n";
    print "E/W: $ew\n";
    print "\n";
}

my $ipcon = Tinkerforge::IPConnection->new(); # Create IP connection
my $gps = Tinkerforge::BrickletGPS->new(&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 cb_coordinates
$gps->register_callback($gps->CALLBACK_COORDINATES, 'cb_coordinates');

# 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->set_coordinates_callback_period(1000);

print "Press key to exit\n";
<STDIN>;
$ipcon->disconnect();

API

Generally, every subroutine of the Perl bindings can report an error as Tinkerforge::Error object via croak(). The object has a get_code() and a get_message() subroutine. There are different error code:

  • Error->ALREADY_CONNECTED = 11
  • Error->NOT_CONNECTED = 12
  • Error->CONNECT_FAILED = 13
  • Error->INVALID_FUNCTION_ID = 21
  • Error->TIMEOUT = 31
  • Error->INVALID_PARAMETER = 41
  • Error->FUNCTION_NOT_SUPPORTED = 42
  • Error->UNKNOWN_ERROR = 43
  • Error->STREAM_OUT_OF_SYNC = 51
  • Error->INVALID_UID = 61
  • Error->NON_ASCII_CHAR_IN_SECRET = 71

All methods listed below are thread-safe.

Basic Functions

BrickletGPS->new($uid, $ipcon)
Parameters:
  • $uid – Type: string
  • $ipcon – Type: IPConnection
Returns:
  • $gps – Type: BrickletGPS

Creates an object with the unique device ID $uid:

$gps = BrickletGPS->new("YOUR_DEVICE_UID", $ipcon);

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

BrickletGPS->get_coordinates()
Return Array:
  • 0: $latitude – Type: int, Range: [0 to 232 - 1]
  • 1: $ns – Type: char
  • 2: $longitude – Type: int, Range: [0 to 232 - 1]
  • 3: $ew – Type: char
  • 4: $pdop – Type: int, Range: [0 to 216 - 1]
  • 5: $hdop – Type: int, Range: [0 to 216 - 1]
  • 6: $vdop – Type: int, Range: [0 to 216 - 1]
  • 7: $epe – Type: int, 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 get_status().

BrickletGPS->get_status()
Return Array:
  • 0: $fix – Type: int, Range: See constants
  • 1: $satellites_view – Type: int, Range: [0 to 255]
  • 2: $satellites_used – Type: int, 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, get_coordinates(), get_altitude() and get_motion() return invalid data
2 2D Fix, only get_coordinates() and get_motion() return valid data
3 3D Fix, get_coordinates(), get_altitude() and get_motion() 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->get_altitude()
Return Array:
  • 0: $altitude – Type: int, Range: [-231 to 231 - 1]
  • 1: $geoidal_separation – Type: int, 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 get_status().

BrickletGPS->get_motion()
Return Array:
  • 0: $course – Type: int, Range: [0 to 232 - 1]
  • 1: $speed – Type: int, 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 get_status().

BrickletGPS->get_date_time()
Return Array:
  • 0: $date – Type: int, Range: [0 to 232 - 1]
  • 1: $time – Type: int, 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

BrickletGPS->restart($restart_type)
Parameters:
  • $restart_type – Type: int, Range: See constants
Returns:
  • undef

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 $restart_type:

  • 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->get_api_version()
Returns:
  • @api_version – Type: [int, ...], 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.

BrickletGPS->get_response_expected($function_id)
Parameters:
  • $function_id – Type: int, Range: See constants
Returns:
  • $response_expected – Type: bool

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 set_response_expected(). 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 $function_id:

  • 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
BrickletGPS->set_response_expected($function_id, $response_expected)
Parameters:
  • $function_id – Type: int, Range: See constants
  • $response_expected – Type: bool
Returns:
  • undef

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 $function_id:

  • 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
BrickletGPS->set_response_expected_all($response_expected)
Parameters:
  • $response_expected – Type: bool
Returns:
  • undef

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

BrickletGPS->get_identity()
Return Array:
  • 0: $uid – Type: string, Length: up to 8
  • 1: $connected_uid – Type: string, Length: up to 8
  • 2: $position – Type: char
  • 3: @hardware_version – Type: [int, ...], Length: 3, Range: [0 to 255]
  • 4: @firmware_version – Type: [int, ...], Length: 3, Range: [0 to 255]
  • 5: $device_identifier – 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' 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

BrickletGPS->register_callback($callback_id, $function)
Parameters:
  • $callback_id – Type: int
  • $function – Type: string
Returns:
  • undef

Registers the given $function name with the given $callback_id.

The available callback IDs with corresponding function signatures are listed below.

BrickletGPS->set_coordinates_callback_period($period)
Parameters:
  • $period – Type: int, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0
Returns:
  • undef

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

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

BrickletGPS->get_coordinates_callback_period()
Returns:
  • $period – Type: int, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0

Returns the period as set by set_coordinates_callback_period().

BrickletGPS->set_status_callback_period($period)
Parameters:
  • $period – Type: int, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0
Returns:
  • undef

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

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

BrickletGPS->get_status_callback_period()
Returns:
  • $period – Type: int, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0

Returns the period as set by set_status_callback_period().

BrickletGPS->set_altitude_callback_period($period)
Parameters:
  • $period – Type: int, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0
Returns:
  • undef

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

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

BrickletGPS->get_altitude_callback_period()
Returns:
  • $period – Type: int, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0

Returns the period as set by set_altitude_callback_period().

BrickletGPS->set_motion_callback_period($period)
Parameters:
  • $period – Type: int, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0
Returns:
  • undef

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

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

BrickletGPS->get_motion_callback_period()
Returns:
  • $period – Type: int, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0

Returns the period as set by set_motion_callback_period().

BrickletGPS->set_date_time_callback_period($period)
Parameters:
  • $period – Type: int, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0
Returns:
  • undef

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

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

BrickletGPS->get_date_time_callback_period()
Returns:
  • $period – Type: int, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0

Returns the period as set by set_date_time_callback_period().

Callbacks

Callbacks can be registered to receive time critical or recurring data from the device. The registration is done with the register_callback() function of the device object. The first parameter is the callback ID and the second parameter the callback function name:

sub my_callback
{
    print "@_[0]";
}

$gps->register_callback(BrickletGPS->CALLBACK_EXAMPLE, 'my_callback')

The callback function will be called from an internal thread of the IP Connection. In contrast to many other programming languages, variables are not automatically shared between threads in Perl. If you want to share a global variable between a callback function and the rest for your program it has to be marked as :shared. See the documentation of the threads::shared Perl module for more details.

The available constants with inherent number and 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.

BrickletGPS->CALLBACK_COORDINATES
Callback Parameters:
  • $latitude – Type: int, Range: [0 to 232 - 1]
  • $ns – Type: char
  • $longitude – Type: int, Range: [0 to 232 - 1]
  • $ew – Type: char
  • $pdop – Type: int, Range: [0 to 216 - 1]
  • $hdop – Type: int, Range: [0 to 216 - 1]
  • $vdop – Type: int, Range: [0 to 216 - 1]
  • $epe – Type: int, Range: [0 to 216 - 1]

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

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

BrickletGPS->CALLBACK_STATUS
Callback Parameters:
  • $fix – Type: int, Range: See constants
  • $satellites_view – Type: int, Range: [0 to 255]
  • $satellites_used – Type: int, Range: [0 to 255]

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

The CALLBACK_STATUS 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
BrickletGPS->CALLBACK_ALTITUDE
Callback Parameters:
  • $altitude – Type: int, Range: [-231 to 231 - 1]
  • $geoidal_separation – Type: int, Range: [-231 to 231 - 1]

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

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

BrickletGPS->CALLBACK_MOTION
Callback Parameters:
  • $course – Type: int, Range: [0 to 232 - 1]
  • $speed – Type: int, Range: [0 to 232 - 1]

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

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

BrickletGPS->CALLBACK_DATE_TIME
Callback Parameters:
  • $date – Type: int, Range: [0 to 232 - 1]
  • $time – Type: int, Range: [0 to 232 - 1]

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

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

Constants

BrickletGPS->DEVICE_IDENTIFIER

This constant is used to identify a GPS Bricklet.

The get_identity() function and the IPConnection->CALLBACK_ENUMERATE callback of the IP Connection have a device_identifier parameter to specify the Brick's or Bricklet's type.

BrickletGPS->DEVICE_DISPLAY_NAME

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