PHP - Line Bricklet

This is the description of the PHP API bindings for the Line Bricklet. General information and technical specifications for the Line Bricklet are summarized in its hardware description.

An installation guide for the PHP API bindings is part of their general description.

Examples

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

Simple

Download (ExampleSimple.php)

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<?php

require_once('Tinkerforge/IPConnection.php');
require_once('Tinkerforge/BrickletLine.php');

use Tinkerforge\IPConnection;
use Tinkerforge\BrickletLine;

const HOST = 'localhost';
const PORT = 4223;
const UID = 'XYZ'; // Change XYZ to the UID of your Line Bricklet

$ipcon = new IPConnection(); // Create IP connection
$l = new BrickletLine(UID, $ipcon); // Create device object

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

// Get current reflectivity
$reflectivity = $l->getReflectivity();
echo "Reflectivity: $reflectivity\n";

echo "Press key to exit\n";
fgetc(fopen('php://stdin', 'r'));
$ipcon->disconnect();

?>

Callback

Download (ExampleCallback.php)

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<?php

require_once('Tinkerforge/IPConnection.php');
require_once('Tinkerforge/BrickletLine.php');

use Tinkerforge\IPConnection;
use Tinkerforge\BrickletLine;

const HOST = 'localhost';
const PORT = 4223;
const UID = 'XYZ'; // Change XYZ to the UID of your Line Bricklet

// Callback function for reflectivity callback
function cb_reflectivity($reflectivity)
{
    echo "Reflectivity: $reflectivity\n";
}

$ipcon = new IPConnection(); // Create IP connection
$l = new BrickletLine(UID, $ipcon); // Create device object

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

// Register reflectivity callback to function cb_reflectivity
$l->registerCallback(BrickletLine::CALLBACK_REFLECTIVITY, 'cb_reflectivity');

// Set period for reflectivity callback to 1s (1000ms)
// Note: The reflectivity callback is only called every second
//       if the reflectivity has changed since the last call!
$l->setReflectivityCallbackPeriod(1000);

echo "Press ctrl+c to exit\n";
$ipcon->dispatchCallbacks(-1); // Dispatch callbacks forever

?>

Threshold

Download (ExampleThreshold.php)

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<?php

require_once('Tinkerforge/IPConnection.php');
require_once('Tinkerforge/BrickletLine.php');

use Tinkerforge\IPConnection;
use Tinkerforge\BrickletLine;

const HOST = 'localhost';
const PORT = 4223;
const UID = 'XYZ'; // Change XYZ to the UID of your Line Bricklet

// Callback function for reflectivity reached callback
function cb_reflectivityReached($reflectivity)
{
    echo "Reflectivity: $reflectivity\n";
}

$ipcon = new IPConnection(); // Create IP connection
$l = new BrickletLine(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 1 second (1000ms)
$l->setDebouncePeriod(1000);

// Register reflectivity reached callback to function cb_reflectivityReached
$l->registerCallback(BrickletLine::CALLBACK_REFLECTIVITY_REACHED,
                     'cb_reflectivityReached');

// Configure threshold for reflectivity "greater than 2000"
$l->setReflectivityCallbackThreshold('>', 2000, 0);

echo "Press ctrl+c to exit\n";
$ipcon->dispatchCallbacks(-1); // Dispatch callbacks forever

?>

API

Functions that return multiple values return them in an associative array.

Basic Functions

class BrickletLine(string $uid, IPConnection $ipcon)

Creates an object with the unique device ID $uid:

<?php   $line = new BrickletLine('YOUR_DEVICE_UID', $ipcon);   ?>

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

int BrickletLine::getReflectivity()

Returns the currently measured reflectivity. The reflectivity is a value between 0 (not reflective) and 4095 (very reflective).

Usually black has a low reflectivity while white has a high reflectivity.

If you want to get the reflectivity periodically, it is recommended to use the CALLBACK_REFLECTIVITY callback and set the period with setReflectivityCallbackPeriod().

Advanced Functions

array BrickletLine::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.

bool BrickletLine::getResponseExpected(int $function_id)

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.

void BrickletLine::setResponseExpected(int $function_id, bool $response_expected)

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:

  • BrickletLine::FUNCTION_SET_REFLECTIVITY_CALLBACK_PERIOD = 2
  • BrickletLine::FUNCTION_SET_REFLECTIVITY_CALLBACK_THRESHOLD = 4
  • BrickletLine::FUNCTION_SET_DEBOUNCE_PERIOD = 6
void BrickletLine::setResponseExpectedAll(bool $response_expected)

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

array BrickletLine::getIdentity()

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 has the keys uid, connected_uid, position, hardware_version, firmware_version and device_identifier.

Callback Configuration Functions

void BrickletLine::registerCallback(int $callback_id, callable $callback, mixed $user_data=NULL)

Registers the given $function with the given $callback_id. The optional $user_data will be passed as the last parameter to the function.

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

void BrickletLine::setReflectivityCallbackPeriod(int $period)

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

The CALLBACK_REFLECTIVITY callback is only triggered if the reflectivity has changed since the last triggering.

The default value is 0.

int BrickletLine::getReflectivityCallbackPeriod()

Returns the period as set by setReflectivityCallbackPeriod().

void BrickletLine::setReflectivityCallbackThreshold(string $option, int $min, int $max)

Sets the thresholds for the CALLBACK_REFLECTIVITY_REACHED callback.

The following options are possible:

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

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

The following constants are available for this function:

  • BrickletLine::THRESHOLD_OPTION_OFF = 'x'
  • BrickletLine::THRESHOLD_OPTION_OUTSIDE = 'o'
  • BrickletLine::THRESHOLD_OPTION_INSIDE = 'i'
  • BrickletLine::THRESHOLD_OPTION_SMALLER = '<'
  • BrickletLine::THRESHOLD_OPTION_GREATER = '>'
array BrickletLine::getReflectivityCallbackThreshold()

Returns the threshold as set by setReflectivityCallbackThreshold().

The following constants are available for this function:

  • BrickletLine::THRESHOLD_OPTION_OFF = 'x'
  • BrickletLine::THRESHOLD_OPTION_OUTSIDE = 'o'
  • BrickletLine::THRESHOLD_OPTION_INSIDE = 'i'
  • BrickletLine::THRESHOLD_OPTION_SMALLER = '<'
  • BrickletLine::THRESHOLD_OPTION_GREATER = '>'

The returned array has the keys option, min and max.

void BrickletLine::setDebouncePeriod(int $debounce)

Sets the period in ms with which the threshold callback

is triggered, if the threshold

keeps being reached.

The default value is 100.

int BrickletLine::getDebouncePeriod()

Returns the debounce period as set by setDebouncePeriod().

Callbacks

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

<?php

function myCallback($param)
{
    echo $param . "\n";
}

$line->registerCallback(BrickletLine::CALLBACK_EXAMPLE, 'myCallback');

?>

The available constants with corresponding function signatures 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.

int BrickletLine::CALLBACK_REFLECTIVITY
<?php   void callback(int $reflectivity [, mixed $user_data])   ?>

This callback is triggered periodically with the period that is set by setReflectivityCallbackPeriod(). The parameter is the reflectivity of the sensor.

The CALLBACK_REFLECTIVITY callback is only triggered if the reflectivity has changed since the last triggering.

int BrickletLine::CALLBACK_REFLECTIVITY_REACHED
<?php   void callback(int $reflectivity [, mixed $user_data])   ?>

This callback is triggered when the threshold as set by setReflectivityCallbackThreshold() is reached. The parameter is the reflectivity of the sensor.

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

Constants

int BrickletLine::DEVICE_IDENTIFIER

This constant is used to identify a Line Bricklet.

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

string BrickletLine::DEVICE_DISPLAY_NAME

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