Perl - Dust Detector Bricklet

This is the description of the Perl API bindings for the Dust Detector Bricklet. General information and technical specifications for the Dust Detector 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::BrickletDustDetector;

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

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

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

# Get current dust density
my $dust_density = $dd->get_dust_density();
print "Dust Density: $dust_density µg/m³\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::BrickletDustDetector;

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

# Callback subroutine for dust density callback
sub cb_dust_density
{
    my ($dust_density) = @_;

    print "Dust Density: $dust_density µg/m³\n";
}

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

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

# Register dust density callback to subroutine cb_dust_density
$dd->register_callback($dd->CALLBACK_DUST_DENSITY, 'cb_dust_density');

# Set period for dust density callback to 1s (1000ms)
# Note: The dust density callback is only called every second
#       if the dust density has changed since the last call!
$dd->set_dust_density_callback_period(1000);

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

Threshold

Download (example_threshold.pl)

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#!/usr/bin/perl

use strict;
use Tinkerforge::IPConnection;
use Tinkerforge::BrickletDustDetector;

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

# Callback subroutine for dust density reached callback
sub cb_dust_density_reached
{
    my ($dust_density) = @_;

    print "Dust Density: $dust_density µg/m³\n";
}

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

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

# Get threshold callbacks with a debounce time of 10 seconds (10000ms)
$dd->set_debounce_period(10000);

# Register dust density reached callback to subroutine cb_dust_density_reached
$dd->register_callback($dd->CALLBACK_DUST_DENSITY_REACHED, 'cb_dust_density_reached');

# Configure threshold for dust density "greater than 10 µg/m³"
$dd->set_dust_density_callback_threshold('>', 10, 0);

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

All methods listed below are thread-safe.

Basic Functions

BrickletDustDetector->new($uid, $ipcon)
Parameters:
  • $uid -- string
  • $ipcon -- IPConnection
Return type:

BrickletDustDetector

Creates an object with the unique device ID $uid:

$dust_detector = BrickletDustDetector->new("YOUR_DEVICE_UID", $ipcon);

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

BrickletDustDetector->get_dust_density()
Return type:int

Returns the dust density in µg/m³.

If you want to get the dust density periodically, it is recommended to use the CALLBACK_DUST_DENSITY callback and set the period with set_dust_density_callback_period().

Advanced Functions

BrickletDustDetector->set_moving_average($average)
Parameters:$average -- int
Return type:undef

Sets the length of a moving averaging for the dust_density.

Setting the length to 0 will turn the averaging completely off. With less averaging, there is more noise on the data.

The range for the averaging is 0-100.

The default value is 100.

BrickletDustDetector->get_moving_average()
Return type:int

Returns the length moving average as set by set_moving_average().

BrickletDustDetector->get_api_version()
Return type:[int, int, int]

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.

BrickletDustDetector->get_response_expected($function_id)
Parameters:$function_id -- int
Return 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.

See set_response_expected() for the list of function ID constants available for this function.

BrickletDustDetector->set_response_expected($function_id, $response_expected)
Parameters:
  • $function_id -- int
  • $response_expected -- bool
Return type:

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 function ID constants are available for this function:

  • BrickletDustDetector->FUNCTION_SET_DUST_DENSITY_CALLBACK_PERIOD = 2
  • BrickletDustDetector->FUNCTION_SET_DUST_DENSITY_CALLBACK_THRESHOLD = 4
  • BrickletDustDetector->FUNCTION_SET_DEBOUNCE_PERIOD = 6
  • BrickletDustDetector->FUNCTION_SET_MOVING_AVERAGE = 10
BrickletDustDetector->set_response_expected_all($response_expected)
Parameters:$response_expected -- bool
Return type:undef

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

BrickletDustDetector->get_identity()
Return type:[string, string, char, [int, int, int], [int, int, int], int]

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.

The returned array contains the elements uid, connected_uid, position, hardware_version, firmware_version and device_identifier.

Callback Configuration Functions

BrickletDustDetector->register_callback($id, $callback)
Parameters:
  • $id -- int
  • $callback -- string
Return type:

undef

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

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

BrickletDustDetector->set_dust_density_callback_period($period)
Parameters:$period -- int
Return type:undef

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

The CALLBACK_DUST_DENSITY callback is only triggered if the dust density has changed since the last triggering.

The default value is 0.

BrickletDustDetector->get_dust_density_callback_period()
Return type:int

Returns the period as set by set_dust_density_callback_period().

BrickletDustDetector->set_dust_density_callback_threshold($option, $min, $max)
Parameters:
  • $option -- char
  • $min -- int
  • $max -- int
Return type:

undef

Sets the thresholds for the CALLBACK_DUST_DENSITY_REACHED callback.

The following options are possible:

Option Description
'x' Callback is turned off
'o' Callback is triggered when the dust density value is outside the min and max values
'i' Callback is triggered when the dust density value is inside the min and max values
'<' Callback is triggered when the dust density value is smaller than the min value (max is ignored)
'>' Callback is triggered when the dust density value is greater than the min value (max is ignored)

The default value is ('x', 0, 0).

The following constants are available for this function:

  • BrickletDustDetector->THRESHOLD_OPTION_OFF = 'x'
  • BrickletDustDetector->THRESHOLD_OPTION_OUTSIDE = 'o'
  • BrickletDustDetector->THRESHOLD_OPTION_INSIDE = 'i'
  • BrickletDustDetector->THRESHOLD_OPTION_SMALLER = '<'
  • BrickletDustDetector->THRESHOLD_OPTION_GREATER = '>'
BrickletDustDetector->get_dust_density_callback_threshold()
Return type:[char, int, int]

Returns the threshold as set by set_dust_density_callback_threshold().

The following constants are available for this function:

  • BrickletDustDetector->THRESHOLD_OPTION_OFF = 'x'
  • BrickletDustDetector->THRESHOLD_OPTION_OUTSIDE = 'o'
  • BrickletDustDetector->THRESHOLD_OPTION_INSIDE = 'i'
  • BrickletDustDetector->THRESHOLD_OPTION_SMALLER = '<'
  • BrickletDustDetector->THRESHOLD_OPTION_GREATER = '>'

The returned array contains the elements option, min and max.

BrickletDustDetector->set_debounce_period($debounce)
Parameters:$debounce -- int
Return type:undef

Sets the period in ms with which the threshold callback

is triggered, if the threshold

keeps being reached.

The default value is 100.

BrickletDustDetector->get_debounce_period()
Return type:int

Returns the debounce period as set by set_debounce_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]";
}

$dust_detector->register_callback(BrickletDustDetector->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.

BrickletDustDetector->CALLBACK_DUST_DENSITY
Parameters:$dust_density -- int

This callback is triggered periodically with the period that is set by set_dust_density_callback_period(). The parameter is the dust density of the sensor.

Der CALLBACK_DUST_DENSITY callback is only triggered if the dust density value has changed since the last triggering.

BrickletDustDetector->CALLBACK_DUST_DENSITY_REACHED
Parameters:$dust_density -- int

This callback is triggered when the threshold as set by set_dust_density_callback_threshold() is reached. The parameter is the dust density of the sensor.

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

Constants

BrickletDustDetector->DEVICE_IDENTIFIER

This constant is used to identify a Dust Detector Bricklet.

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

BrickletDustDetector->DEVICE_DISPLAY_NAME

This constant represents the human readable name of a Dust Detector Bricklet.