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PHP - Linear Poti Bricklet

This is the description of the PHP API bindings for the Linear Poti Bricklet. General information and technical specifications for the Linear Poti 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/BrickletLinearPoti.php');

use Tinkerforge\IPConnection;
use Tinkerforge\BrickletLinearPoti;

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

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

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

// Get current position
$position = $lp->getPosition();
echo "Position: $position %\n"; // Range: 0 to 100

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/BrickletLinearPoti.php');

use Tinkerforge\IPConnection;
use Tinkerforge\BrickletLinearPoti;

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

// Callback function for position callback
function cb_position($position)
{
    echo "Position: $position %\n"; // Range: 0 to 100
}

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

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

// Register position callback to function cb_position
$lp->registerCallback(BrickletLinearPoti::CALLBACK_POSITION, 'cb_position');

// Set period for position callback to 0.05s (50ms)
// Note: The position callback is only called every 0.05 seconds
//       if the position has changed since the last call!
$lp->setPositionCallbackPeriod(50);

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 BrickletLinearPoti(string $uid, IPConnection $ipcon)
Parameters:
  • $uid – Type: string
  • $ipcon – Type: IPConnection
Returns:
  • $linear_poti – Type: BrickletLinearPoti

Creates an object with the unique device ID $uid:

<?php   $linear_poti = new BrickletLinearPoti('YOUR_DEVICE_UID', $ipcon);   ?>

This object can then be used after the IP Connection is connected.

int BrickletLinearPoti::getPosition()
Returns:
  • $position – Type: int, Unit: 1 %, Range: [0 to 100]

Returns the position of the linear potentiometer. The value is between 0% (slider down) and 100% (slider up).

If you want to get the position periodically, it is recommended to use the CALLBACK_POSITION callback and set the period with setPositionCallbackPeriod().

Advanced Functions

int BrickletLinearPoti::getAnalogValue()
Returns:
  • $value – Type: int, Range: [0 to 212 - 1]

Returns the value as read by a 12-bit analog-to-digital converter.

Note

The value returned by getPosition() is averaged over several samples to yield less noise, while getAnalogValue() gives back raw unfiltered analog values. The only reason to use getAnalogValue() is, if you need the full resolution of the analog-to-digital converter.

If you want the analog value periodically, it is recommended to use the CALLBACK_ANALOG_VALUE callback and set the period with setAnalogValueCallbackPeriod().

array BrickletLinearPoti::getIdentity()
Return Array:
  • 'uid' – Type: string, Length: up to 8
  • 'connected_uid' – Type: string, Length: up to 8
  • 'position' – Type: string, Range: ['a' to 'h', 'z']
  • 'hardware_version' – Type: array(int, ...), Length: 3
    • 0: $major – Type: int, Range: [0 to 255]
    • 1: $minor – Type: int, Range: [0 to 255]
    • 2: $revision – Type: int, Range: [0 to 255]
  • 'firmware_version' – Type: array(int, ...), Length: 3
    • 0: $major – Type: int, Range: [0 to 255]
    • 1: $minor – Type: int, Range: [0 to 255]
    • 2: $revision – Type: int, Range: [0 to 255]
  • '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', 'd', 'e', 'f', 'g' or 'h' (Bricklet Port). A Bricklet connected to an Isolator Bricklet is always at position 'z'.

The device identifier numbers can be found here. There is also a constant for the device identifier of this Bricklet.

Callback Configuration Functions

void BrickletLinearPoti::registerCallback(int $callback_id, callable $callback, mixed $user_data=NULL)
Parameters:
  • $callback_id – Type: int
  • $callback – Type: callable
  • $user_data – Type: mixed

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 BrickletLinearPoti::setPositionCallbackPeriod(int $period)
Parameters:
  • $period – Type: int, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0

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

The CALLBACK_POSITION callback is only triggered if the position has changed since the last triggering.

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

Returns the period as set by setPositionCallbackPeriod().

void BrickletLinearPoti::setAnalogValueCallbackPeriod(int $period)
Parameters:
  • $period – Type: int, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0

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

The CALLBACK_ANALOG_VALUE callback is only triggered if the analog value has changed since the last triggering.

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

Returns the period as set by setAnalogValueCallbackPeriod().

void BrickletLinearPoti::setPositionCallbackThreshold(string $option, int $min, int $max)
Parameters:
  • $option – Type: string, Range: See constants, Default: 'x'
  • $min – Type: int, Unit: 1 %, Range: [0 to 216 - 1], Default: 0
  • $max – Type: int, Unit: 1 %, Range: [0 to 216 - 1], Default: 0

Sets the thresholds for the CALLBACK_POSITION_REACHED callback.

The following options are possible:

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

The following constants are available for this function:

For $option:

  • BrickletLinearPoti::THRESHOLD_OPTION_OFF = 'x'
  • BrickletLinearPoti::THRESHOLD_OPTION_OUTSIDE = 'o'
  • BrickletLinearPoti::THRESHOLD_OPTION_INSIDE = 'i'
  • BrickletLinearPoti::THRESHOLD_OPTION_SMALLER = '<'
  • BrickletLinearPoti::THRESHOLD_OPTION_GREATER = '>'
array BrickletLinearPoti::getPositionCallbackThreshold()
Return Array:
  • 'option' – Type: string, Range: See constants, Default: 'x'
  • 'min' – Type: int, Unit: 1 %, Range: [0 to 216 - 1], Default: 0
  • 'max' – Type: int, Unit: 1 %, Range: [0 to 216 - 1], Default: 0

Returns the threshold as set by setPositionCallbackThreshold().

The following constants are available for this function:

For $option:

  • BrickletLinearPoti::THRESHOLD_OPTION_OFF = 'x'
  • BrickletLinearPoti::THRESHOLD_OPTION_OUTSIDE = 'o'
  • BrickletLinearPoti::THRESHOLD_OPTION_INSIDE = 'i'
  • BrickletLinearPoti::THRESHOLD_OPTION_SMALLER = '<'
  • BrickletLinearPoti::THRESHOLD_OPTION_GREATER = '>'
void BrickletLinearPoti::setAnalogValueCallbackThreshold(string $option, int $min, int $max)
Parameters:
  • $option – Type: string, Range: See constants, Default: 'x'
  • $min – Type: int, Range: [0 to 216 - 1], Default: 0
  • $max – Type: int, Range: [0 to 216 - 1], Default: 0

Sets the thresholds for the CALLBACK_ANALOG_VALUE_REACHED callback.

The following options are possible:

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

The following constants are available for this function:

For $option:

  • BrickletLinearPoti::THRESHOLD_OPTION_OFF = 'x'
  • BrickletLinearPoti::THRESHOLD_OPTION_OUTSIDE = 'o'
  • BrickletLinearPoti::THRESHOLD_OPTION_INSIDE = 'i'
  • BrickletLinearPoti::THRESHOLD_OPTION_SMALLER = '<'
  • BrickletLinearPoti::THRESHOLD_OPTION_GREATER = '>'
array BrickletLinearPoti::getAnalogValueCallbackThreshold()
Return Array:
  • 'option' – Type: string, Range: See constants, Default: 'x'
  • 'min' – Type: int, Range: [0 to 216 - 1], Default: 0
  • 'max' – Type: int, Range: [0 to 216 - 1], Default: 0

Returns the threshold as set by setAnalogValueCallbackThreshold().

The following constants are available for this function:

For $option:

  • BrickletLinearPoti::THRESHOLD_OPTION_OFF = 'x'
  • BrickletLinearPoti::THRESHOLD_OPTION_OUTSIDE = 'o'
  • BrickletLinearPoti::THRESHOLD_OPTION_INSIDE = 'i'
  • BrickletLinearPoti::THRESHOLD_OPTION_SMALLER = '<'
  • BrickletLinearPoti::THRESHOLD_OPTION_GREATER = '>'
void BrickletLinearPoti::setDebouncePeriod(int $debounce)
Parameters:
  • $debounce – Type: int, Unit: 1 ms, Range: [0 to 232 - 1], Default: 100

Sets the period with which the threshold callbacks

are triggered, if the thresholds

keep being reached.

int BrickletLinearPoti::getDebouncePeriod()
Returns:
  • $debounce – Type: int, Unit: 1 ms, Range: [0 to 232 - 1], Default: 100

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";
}

$linear_poti->registerCallback(BrickletLinearPoti::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 BrickletLinearPoti::CALLBACK_POSITION
<?php   void callback(int $position [, mixed $user_data])   ?>
Callback Parameters:
  • $position – Type: int, Unit: 1 %, Range: [0 to 100]
  • $user_data – Type: mixed

This callback is triggered periodically with the period that is set by setPositionCallbackPeriod(). The parameter is the position of the linear potentiometer.

The CALLBACK_POSITION callback is only triggered if the position has changed since the last triggering.

int BrickletLinearPoti::CALLBACK_ANALOG_VALUE
<?php   void callback(int $value [, mixed $user_data])   ?>
Callback Parameters:
  • $value – Type: int, Range: [0 to 212 - 1]
  • $user_data – Type: mixed

This callback is triggered periodically with the period that is set by setAnalogValueCallbackPeriod(). The parameter is the analog value of the Linear Potentiometer.

The CALLBACK_ANALOG_VALUE callback is only triggered if the position has changed since the last triggering.

int BrickletLinearPoti::CALLBACK_POSITION_REACHED
<?php   void callback(int $position [, mixed $user_data])   ?>
Callback Parameters:
  • $position – Type: int, Unit: 1 %, Range: [0 to 100]
  • $user_data – Type: mixed

This callback is triggered when the threshold as set by setPositionCallbackThreshold() is reached. The parameter is the position of the linear potentiometer.

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

int BrickletLinearPoti::CALLBACK_ANALOG_VALUE_REACHED
<?php   void callback(int $value [, mixed $user_data])   ?>
Callback Parameters:
  • $value – Type: int, Range: [0 to 212 - 1]
  • $user_data – Type: mixed

This callback is triggered when the threshold as set by setAnalogValueCallbackThreshold() is reached. The parameter is the analog value of the linear potentiometer.

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

Virtual Functions

Virtual functions don't communicate with the device itself, but operate only on the API bindings device object. They can be called without the corresponding IP Connection object being connected.

array BrickletLinearPoti::getAPIVersion()
Return Array:
  • $api_version – Type: array(int, ...), Length: 3
    • 0: $major – Type: int, Range: [0 to 255]
    • 1: $minor – Type: int, Range: [0 to 255]
    • 2: $revision – Type: int, Range: [0 to 255]

Returns the version of the API definition 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 BrickletLinearPoti::getResponseExpected(int $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 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 sent and errors are silently ignored, because they cannot be detected.

The following constants are available for this function:

For $function_id:

  • BrickletLinearPoti::FUNCTION_SET_POSITION_CALLBACK_PERIOD = 3
  • BrickletLinearPoti::FUNCTION_SET_ANALOG_VALUE_CALLBACK_PERIOD = 5
  • BrickletLinearPoti::FUNCTION_SET_POSITION_CALLBACK_THRESHOLD = 7
  • BrickletLinearPoti::FUNCTION_SET_ANALOG_VALUE_CALLBACK_THRESHOLD = 9
  • BrickletLinearPoti::FUNCTION_SET_DEBOUNCE_PERIOD = 11
void BrickletLinearPoti::setResponseExpected(int $function_id, bool $response_expected)
Parameters:
  • $function_id – Type: int, Range: See constants
  • $response_expected – Type: bool

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 sent and errors are silently ignored, because they cannot be detected.

The following constants are available for this function:

For $function_id:

  • BrickletLinearPoti::FUNCTION_SET_POSITION_CALLBACK_PERIOD = 3
  • BrickletLinearPoti::FUNCTION_SET_ANALOG_VALUE_CALLBACK_PERIOD = 5
  • BrickletLinearPoti::FUNCTION_SET_POSITION_CALLBACK_THRESHOLD = 7
  • BrickletLinearPoti::FUNCTION_SET_ANALOG_VALUE_CALLBACK_THRESHOLD = 9
  • BrickletLinearPoti::FUNCTION_SET_DEBOUNCE_PERIOD = 11
void BrickletLinearPoti::setResponseExpectedAll(bool $response_expected)
Parameters:
  • $response_expected – Type: bool

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

Constants

int BrickletLinearPoti::DEVICE_IDENTIFIER

This constant is used to identify a Linear Poti Bricklet.

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

string BrickletLinearPoti::DEVICE_DISPLAY_NAME

This constant represents the human readable name of a Linear Poti Bricklet.