PHP - Accelerometer Bricklet

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

use Tinkerforge\IPConnection;
use Tinkerforge\BrickletAccelerometer;

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

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

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

// Get current acceleration
$acceleration = $a->getAcceleration();

echo "Acceleration [X]: " . $acceleration['x']/1000.0 . " g\n";
echo "Acceleration [Y]: " . $acceleration['y']/1000.0 . " g\n";
echo "Acceleration [Z]: " . $acceleration['z']/1000.0 . " g\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/BrickletAccelerometer.php');

use Tinkerforge\IPConnection;
use Tinkerforge\BrickletAccelerometer;

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

// Callback function for acceleration callback
function cb_acceleration($x, $y, $z)
{
    echo "Acceleration [X]: " . $x/1000.0 . " g\n";
    echo "Acceleration [Y]: " . $y/1000.0 . " g\n";
    echo "Acceleration [Z]: " . $z/1000.0 . " g\n";
    echo "\n";
}

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

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

// Register acceleration callback to function cb_acceleration
$a->registerCallback(BrickletAccelerometer::CALLBACK_ACCELERATION, 'cb_acceleration');

// Set period for acceleration callback to 1s (1000ms)
// Note: The acceleration callback is only called every second
//       if the acceleration has changed since the last call!
$a->setAccelerationCallbackPeriod(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/BrickletAccelerometer.php');

use Tinkerforge\IPConnection;
use Tinkerforge\BrickletAccelerometer;

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

// Callback function for acceleration reached callback
function cb_accelerationReached($x, $y, $z)
{
    echo "Acceleration [X]: " . $x/1000.0 . " g\n";
    echo "Acceleration [Y]: " . $y/1000.0 . " g\n";
    echo "Acceleration [Z]: " . $z/1000.0 . " g\n";
    echo "\n";
}

$ipcon = new IPConnection(); // Create IP connection
$a = new BrickletAccelerometer(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)
$a->setDebouncePeriod(10000);

// Register acceleration reached callback to function cb_accelerationReached
$a->registerCallback(BrickletAccelerometer::CALLBACK_ACCELERATION_REACHED,
                     'cb_accelerationReached');

// Configure threshold for acceleration "greater than 2 g, 2 g, 2 g"
$a->setAccelerationCallbackThreshold('>', 2*1000, 0, 2*1000, 0, 2*1000, 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 BrickletAccelerometer(string $uid, IPConnection $ipcon)

Creates an object with the unique device ID $uid:

<?php   $accelerometer = new BrickletAccelerometer('YOUR_DEVICE_UID', $ipcon);   ?>

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

array BrickletAccelerometer::getAcceleration()

Returns the acceleration in x, y and z direction. The values are given in g/1000 (1g = 9.80665m/s²), not to be confused with grams.

If you want to get the acceleration periodically, it is recommended to use the CALLBACK_ACCELERATION callback and set the period with setAccelerationCallbackPeriod().

The returned array has the keys x, y and z.

int BrickletAccelerometer::getTemperature()

Returns the temperature of the accelerometer in °C.

void BrickletAccelerometer::ledOn()

Enables the LED on the Bricklet.

void BrickletAccelerometer::ledOff()

Disables the LED on the Bricklet.

bool BrickletAccelerometer::isLEDOn()

Returns true if the LED is enabled, false otherwise.

Advanced Functions

void BrickletAccelerometer::setConfiguration(int $data_rate, int $full_scale, int $filter_bandwidth)

Configures the data rate, full scale range and filter bandwidth. Possible values are:

  • Data rate of 0Hz to 1600Hz.
  • Full scale range of -2G to +2G up to -16G to +16G.
  • Filter bandwidth between 50Hz and 800Hz.

Decreasing data rate or full scale range will also decrease the noise on the data.

The default values are 100Hz data rate, -4G to +4G range and 200Hz filter bandwidth.

The following constants are available for this function:

  • BrickletAccelerometer::DATA_RATE_OFF = 0
  • BrickletAccelerometer::DATA_RATE_3HZ = 1
  • BrickletAccelerometer::DATA_RATE_6HZ = 2
  • BrickletAccelerometer::DATA_RATE_12HZ = 3
  • BrickletAccelerometer::DATA_RATE_25HZ = 4
  • BrickletAccelerometer::DATA_RATE_50HZ = 5
  • BrickletAccelerometer::DATA_RATE_100HZ = 6
  • BrickletAccelerometer::DATA_RATE_400HZ = 7
  • BrickletAccelerometer::DATA_RATE_800HZ = 8
  • BrickletAccelerometer::DATA_RATE_1600HZ = 9
  • BrickletAccelerometer::FULL_SCALE_2G = 0
  • BrickletAccelerometer::FULL_SCALE_4G = 1
  • BrickletAccelerometer::FULL_SCALE_6G = 2
  • BrickletAccelerometer::FULL_SCALE_8G = 3
  • BrickletAccelerometer::FULL_SCALE_16G = 4
  • BrickletAccelerometer::FILTER_BANDWIDTH_800HZ = 0
  • BrickletAccelerometer::FILTER_BANDWIDTH_400HZ = 1
  • BrickletAccelerometer::FILTER_BANDWIDTH_200HZ = 2
  • BrickletAccelerometer::FILTER_BANDWIDTH_50HZ = 3
array BrickletAccelerometer::getConfiguration()

Returns the configuration as set by setConfiguration().

The following constants are available for this function:

  • BrickletAccelerometer::DATA_RATE_OFF = 0
  • BrickletAccelerometer::DATA_RATE_3HZ = 1
  • BrickletAccelerometer::DATA_RATE_6HZ = 2
  • BrickletAccelerometer::DATA_RATE_12HZ = 3
  • BrickletAccelerometer::DATA_RATE_25HZ = 4
  • BrickletAccelerometer::DATA_RATE_50HZ = 5
  • BrickletAccelerometer::DATA_RATE_100HZ = 6
  • BrickletAccelerometer::DATA_RATE_400HZ = 7
  • BrickletAccelerometer::DATA_RATE_800HZ = 8
  • BrickletAccelerometer::DATA_RATE_1600HZ = 9
  • BrickletAccelerometer::FULL_SCALE_2G = 0
  • BrickletAccelerometer::FULL_SCALE_4G = 1
  • BrickletAccelerometer::FULL_SCALE_6G = 2
  • BrickletAccelerometer::FULL_SCALE_8G = 3
  • BrickletAccelerometer::FULL_SCALE_16G = 4
  • BrickletAccelerometer::FILTER_BANDWIDTH_800HZ = 0
  • BrickletAccelerometer::FILTER_BANDWIDTH_400HZ = 1
  • BrickletAccelerometer::FILTER_BANDWIDTH_200HZ = 2
  • BrickletAccelerometer::FILTER_BANDWIDTH_50HZ = 3

The returned array has the keys data_rate, full_scale and filter_bandwidth.

array BrickletAccelerometer::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 BrickletAccelerometer::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 BrickletAccelerometer::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:

  • BrickletAccelerometer::FUNCTION_SET_ACCELERATION_CALLBACK_PERIOD = 2
  • BrickletAccelerometer::FUNCTION_SET_ACCELERATION_CALLBACK_THRESHOLD = 4
  • BrickletAccelerometer::FUNCTION_SET_DEBOUNCE_PERIOD = 6
  • BrickletAccelerometer::FUNCTION_SET_CONFIGURATION = 9
  • BrickletAccelerometer::FUNCTION_LED_ON = 11
  • BrickletAccelerometer::FUNCTION_LED_OFF = 12
void BrickletAccelerometer::setResponseExpectedAll(bool $response_expected)

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

array BrickletAccelerometer::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 BrickletAccelerometer::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 BrickletAccelerometer::setAccelerationCallbackPeriod(int $period)

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

The CALLBACK_ACCELERATION callback is only triggered if the acceleration has changed since the last triggering.

The default value is 0.

int BrickletAccelerometer::getAccelerationCallbackPeriod()

Returns the period as set by setAccelerationCallbackPeriod().

void BrickletAccelerometer::setAccelerationCallbackThreshold(string $option, int $min_x, int $max_x, int $min_y, int $max_y, int $min_z, int $max_z)

Sets the thresholds for the CALLBACK_ACCELERATION_REACHED callback.

The following options are possible:

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

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

The following constants are available for this function:

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

Returns the threshold as set by setAccelerationCallbackThreshold().

The following constants are available for this function:

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

The returned array has the keys option, min_x, max_x, min_y, max_y, min_z and max_z.

void BrickletAccelerometer::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 BrickletAccelerometer::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";
}

$accelerometer->registerCallback(BrickletAccelerometer::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 BrickletAccelerometer::CALLBACK_ACCELERATION
<?php   void callback(int $x, int $y, int $z [, mixed $user_data])   ?>

This callback is triggered periodically with the period that is set by setAccelerationCallbackPeriod(). The parameters are the X, Y and Z acceleration.

The CALLBACK_ACCELERATION callback is only triggered if the acceleration has changed since the last triggering.

int BrickletAccelerometer::CALLBACK_ACCELERATION_REACHED
<?php   void callback(int $x, int $y, int $z [, mixed $user_data])   ?>

This callback is triggered when the threshold as set by setAccelerationCallbackThreshold() is reached. The parameters are the X, Y and Z acceleration.

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

Constants

int BrickletAccelerometer::DEVICE_IDENTIFIER

This constant is used to identify a Accelerometer 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 BrickletAccelerometer::DEVICE_DISPLAY_NAME

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