PHP - Hall Effect Bricklet

This is the description of the PHP API bindings for the Hall Effect Bricklet. General information and technical specifications for the Hall Effect 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/BrickletHallEffect.php');

use Tinkerforge\IPConnection;
use Tinkerforge\BrickletHallEffect;

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

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

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

// Get current edge count without reset
$count = $he->getEdgeCount(FALSE);
echo "Count: $count\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/BrickletHallEffect.php');

use Tinkerforge\IPConnection;
use Tinkerforge\BrickletHallEffect;

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

// Callback function for edge count callback
function cb_edgeCount($count, $value)
{
    echo "Count: $count\n";
}

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

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

// Register edge count callback to function cb_edgeCount
$he->registerCallback(BrickletHallEffect::CALLBACK_EDGE_COUNT, 'cb_edgeCount');

// Set period for edge count callback to 0.05s (50ms)
// Note: The edge count callback is only called every 0.05 seconds
//       if the edge count has changed since the last call!
$he->setEdgeCountCallbackPeriod(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 BrickletHallEffect(string $uid, IPConnection $ipcon)

Creates an object with the unique device ID $uid:

<?php   $hall_effect = new BrickletHallEffect('YOUR_DEVICE_UID', $ipcon);   ?>

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

bool BrickletHallEffect::getValue()

Returns true if a magnetic field of 35 Gauss (3.5mT) or greater is detected.

int BrickletHallEffect::getEdgeCount(bool $reset_counter)

Returns the current value of the edge counter. You can configure edge type (rising, falling, both) that is counted with setEdgeCountConfig().

If you set the reset counter to true, the count is set back to 0 directly after it is read.

Advanced Functions

void BrickletHallEffect::setEdgeCountConfig(int $edge_type, int $debounce)

The edge type parameter configures if rising edges, falling edges or both are counted. Possible edge types are:

  • 0 = rising (default)
  • 1 = falling
  • 2 = both

A magnetic field of 35 Gauss (3.5mT) or greater causes a falling edge and a magnetic field of 25 Gauss (2.5mT) or smaller causes a rising edge.

If a magnet comes near the Bricklet the signal goes low (falling edge), if a magnet is removed from the vicinity the signal goes high (rising edge).

The debounce time is given in ms.

Configuring an edge counter resets its value to 0.

If you don't know what any of this means, just leave it at default. The default configuration is very likely OK for you.

Default values: 0 (edge type) and 100ms (debounce time)

The following constants are available for this function:

  • BrickletHallEffect::EDGE_TYPE_RISING = 0
  • BrickletHallEffect::EDGE_TYPE_FALLING = 1
  • BrickletHallEffect::EDGE_TYPE_BOTH = 2
array BrickletHallEffect::getEdgeCountConfig()

Returns the edge type and debounce time as set by setEdgeCountConfig().

The following constants are available for this function:

  • BrickletHallEffect::EDGE_TYPE_RISING = 0
  • BrickletHallEffect::EDGE_TYPE_FALLING = 1
  • BrickletHallEffect::EDGE_TYPE_BOTH = 2

The returned array has the keys edge_type and debounce.

array BrickletHallEffect::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 BrickletHallEffect::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 BrickletHallEffect::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:

  • BrickletHallEffect::FUNCTION_SET_EDGE_COUNT_CONFIG = 3
  • BrickletHallEffect::FUNCTION_SET_EDGE_INTERRUPT = 5
  • BrickletHallEffect::FUNCTION_SET_EDGE_COUNT_CALLBACK_PERIOD = 7
void BrickletHallEffect::setResponseExpectedAll(bool $response_expected)

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

array BrickletHallEffect::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 BrickletHallEffect::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 BrickletHallEffect::setEdgeInterrupt(int $edges)

Sets the number of edges until an interrupt is invoked.

If edges is set to n, an interrupt is invoked for every n-th detected edge.

If edges is set to 0, the interrupt is disabled.

Default value is 0.

int BrickletHallEffect::getEdgeInterrupt()

Returns the edges as set by setEdgeInterrupt().

void BrickletHallEffect::setEdgeCountCallbackPeriod(int $period)

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

The CALLBACK_EDGE_COUNT callback is only triggered if the edge count has changed since the last triggering.

The default value is 0.

int BrickletHallEffect::getEdgeCountCallbackPeriod()

Returns the period as set by setEdgeCountCallbackPeriod().

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";
}

$hall_effect->registerCallback(BrickletHallEffect::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 BrickletHallEffect::CALLBACK_EDGE_COUNT
<?php   void callback(int $count, bool $value [, mixed $user_data])   ?>

This callback is triggered periodically with the period that is set by setEdgeCountCallbackPeriod(). The parameters are the current count and the current value (see getValue() and getEdgeCount()).

The CALLBACK_EDGE_COUNT callback is only triggered if the count or value changed since the last triggering.

Constants

int BrickletHallEffect::DEVICE_IDENTIFIER

This constant is used to identify a Hall Effect 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 BrickletHallEffect::DEVICE_DISPLAY_NAME

This constant represents the human readable name of a Hall Effect Bricklet.