PHP - Rotary Encoder Bricklet

This is the description of the PHP API bindings for the Rotary Encoder Bricklet. General information and technical specifications for the Rotary Encoder 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/BrickletRotaryEncoder.php');

use Tinkerforge\IPConnection;
use Tinkerforge\BrickletRotaryEncoder;

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

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

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

// Get current count without reset
$count = $re->getCount(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/BrickletRotaryEncoder.php');

use Tinkerforge\IPConnection;
use Tinkerforge\BrickletRotaryEncoder;

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

// Callback function for count callback
function cb_count($count)
{
    echo "Count: $count\n";
}

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

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

// Register count callback to function cb_count
$re->registerCallback(BrickletRotaryEncoder::CALLBACK_COUNT, 'cb_count');

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

Creates an object with the unique device ID $uid:

<?php   $rotary_encoder = new BrickletRotaryEncoder('YOUR_DEVICE_UID', $ipcon);   ?>

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

int BrickletRotaryEncoder::getCount(bool $reset)

Returns the current count of the encoder. If you set reset to true, the count is set back to 0 directly after the current count is read.

The encoder has 24 steps per rotation

Turning the encoder to the left decrements the counter, so a negative count is possible.

bool BrickletRotaryEncoder::isPressed()

Returns true if the button is pressed and false otherwise.

It is recommended to use the CALLBACK_PRESSED and CALLBACK_RELEASED callbacks to handle the button.

Advanced Functions

array BrickletRotaryEncoder::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 BrickletRotaryEncoder::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 BrickletRotaryEncoder::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:

  • BrickletRotaryEncoder::FUNCTION_SET_COUNT_CALLBACK_PERIOD = 2
  • BrickletRotaryEncoder::FUNCTION_SET_COUNT_CALLBACK_THRESHOLD = 4
  • BrickletRotaryEncoder::FUNCTION_SET_DEBOUNCE_PERIOD = 6
void BrickletRotaryEncoder::setResponseExpectedAll(bool $response_expected)

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

array BrickletRotaryEncoder::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 BrickletRotaryEncoder::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 BrickletRotaryEncoder::setCountCallbackPeriod(int $period)

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

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

The default value is 0.

int BrickletRotaryEncoder::getCountCallbackPeriod()

Returns the period as set by setCountCallbackPeriod().

void BrickletRotaryEncoder::setCountCallbackThreshold(string $option, int $min, int $max)

Sets the thresholds for the CALLBACK_COUNT_REACHED callback.

The following options are possible:

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

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

The following constants are available for this function:

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

Returns the threshold as set by setCountCallbackThreshold().

The following constants are available for this function:

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

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

void BrickletRotaryEncoder::setDebouncePeriod(int $debounce)

Sets the period in ms with which the threshold callback

is triggered, if the thresholds

keeps being reached.

The default value is 100.

int BrickletRotaryEncoder::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";
}

$rotary_encoder->registerCallback(BrickletRotaryEncoder::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 BrickletRotaryEncoder::CALLBACK_COUNT
<?php   void callback(int $count [, mixed $user_data])   ?>

This callback is triggered periodically with the period that is set by setCountCallbackPeriod(). The parameter is the count of the encoder.

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

int BrickletRotaryEncoder::CALLBACK_COUNT_REACHED
<?php   void callback(int $count [, mixed $user_data])   ?>

This callback is triggered when the threshold as set by setCountCallbackThreshold() is reached. The parameter is the count of the encoder.

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

int BrickletRotaryEncoder::CALLBACK_PRESSED
<?php   void callback([mixed $user_data])   ?>

This callback is triggered when the button is pressed.

int BrickletRotaryEncoder::CALLBACK_RELEASED
<?php   void callback([mixed $user_data])   ?>

This callback is triggered when the button is released.

Constants

int BrickletRotaryEncoder::DEVICE_IDENTIFIER

This constant is used to identify a Rotary Encoder 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 BrickletRotaryEncoder::DEVICE_DISPLAY_NAME

This constant represents the human readable name of a Rotary Encoder Bricklet.