PHP - Barometer Bricklet

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

use Tinkerforge\IPConnection;
use Tinkerforge\BrickletBarometer;

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

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

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

// Get current air pressure
$air_pressure = $b->getAirPressure();
echo "Air Pressure: " . $air_pressure/1000.0 . " mbar\n";

// Get current altitude
$altitude = $b->getAltitude();
echo "Altitude: " . $altitude/100.0 . " m\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/BrickletBarometer.php');

use Tinkerforge\IPConnection;
use Tinkerforge\BrickletBarometer;

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

// Callback function for air pressure callback
function cb_airPressure($air_pressure)
{
    echo "Air Pressure: " . $air_pressure/1000.0 . " mbar\n";
}

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

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

// Register air pressure callback to function cb_airPressure
$b->registerCallback(BrickletBarometer::CALLBACK_AIR_PRESSURE, 'cb_airPressure');

// Set period for air pressure callback to 1s (1000ms)
// Note: The air pressure callback is only called every second
//       if the air pressure has changed since the last call!
$b->setAirPressureCallbackPeriod(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/BrickletBarometer.php');

use Tinkerforge\IPConnection;
use Tinkerforge\BrickletBarometer;

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

// Callback function for air pressure reached callback
function cb_airPressureReached($air_pressure)
{
    echo "Air Pressure: " . $air_pressure/1000.0 . " mbar\n";
    echo "Enjoy the potentially good weather!\n";
}

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

// Register air pressure reached callback to function cb_airPressureReached
$b->registerCallback(BrickletBarometer::CALLBACK_AIR_PRESSURE_REACHED,
                     'cb_airPressureReached');

// Configure threshold for air pressure "greater than 1025 mbar"
$b->setAirPressureCallbackThreshold('>', 1025*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 BrickletBarometer(string $uid, IPConnection $ipcon)

Creates an object with the unique device ID $uid:

<?php   $barometer = new BrickletBarometer('YOUR_DEVICE_UID', $ipcon);   ?>

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

int BrickletBarometer::getAirPressure()

Returns the air pressure of the air pressure sensor. The value has a range of 10000 to 1200000 and is given in mbar/1000, i.e. a value of 1001092 means that an air pressure of 1001.092 mbar is measured.

If you want to get the air pressure periodically, it is recommended to use the CALLBACK_AIR_PRESSURE callback and set the period with setAirPressureCallbackPeriod().

int BrickletBarometer::getAltitude()

Returns the relative altitude of the air pressure sensor. The value is given in cm and is calculated based on the difference between the current air pressure and the reference air pressure that can be set with setReferenceAirPressure().

If you want to get the altitude periodically, it is recommended to use the CALLBACK_ALTITUDE callback and set the period with setAltitudeCallbackPeriod().

void BrickletBarometer::setReferenceAirPressure(int $air_pressure)

Sets the reference air pressure in mbar/1000 for the altitude calculation. Valid values are between 10000 and 1200000. Setting the reference to the current air pressure results in a calculated altitude of 0cm. Passing 0 is a shortcut for passing the current air pressure as reference.

Well known reference values are the Q codes QNH and QFE used in aviation.

The default value is 1013.25mbar.

int BrickletBarometer::getReferenceAirPressure()

Returns the reference air pressure as set by setReferenceAirPressure().

Advanced Functions

int BrickletBarometer::getChipTemperature()

Returns the temperature of the air pressure sensor. The value has a range of -4000 to 8500 and is given in °C/100, i.e. a value of 2007 means that a temperature of 20.07 °C is measured.

This temperature is used internally for temperature compensation of the air pressure measurement. It is not as accurate as the temperature measured by the Temperature Bricklet or the Temperature IR Bricklet.

void BrickletBarometer::setAveraging(int $moving_average_pressure, int $average_pressure, int $average_temperature)

Sets the different averaging parameters. It is possible to set the length of a normal averaging for the temperature and pressure, as well as an additional length of a moving average for the pressure. The moving average is calculated from the normal averages. There is no moving average for the temperature.

The maximum length for the pressure average is 10, for the temperature average is 255 and for the moving average is 25.

Setting the all three parameters to 0 will turn the averaging completely off. If the averaging is off, there is lots of noise on the data, but the data is without delay. Thus we recommend to turn the averaging off if the Barometer Bricklet data is to be used for sensor fusion with other sensors.

The default values are 10 for the normal averages and 25 for the moving average.

New in version 2.0.1 (Plugin).

array BrickletBarometer::getAveraging()

Returns the averaging configuration as set by setAveraging().

New in version 2.0.1 (Plugin).

The returned array has the keys moving_average_pressure, average_pressure and average_temperature.

array BrickletBarometer::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 BrickletBarometer::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 BrickletBarometer::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:

  • BrickletBarometer::FUNCTION_SET_AIR_PRESSURE_CALLBACK_PERIOD = 3
  • BrickletBarometer::FUNCTION_SET_ALTITUDE_CALLBACK_PERIOD = 5
  • BrickletBarometer::FUNCTION_SET_AIR_PRESSURE_CALLBACK_THRESHOLD = 7
  • BrickletBarometer::FUNCTION_SET_ALTITUDE_CALLBACK_THRESHOLD = 9
  • BrickletBarometer::FUNCTION_SET_DEBOUNCE_PERIOD = 11
  • BrickletBarometer::FUNCTION_SET_REFERENCE_AIR_PRESSURE = 13
  • BrickletBarometer::FUNCTION_SET_AVERAGING = 20
void BrickletBarometer::setResponseExpectedAll(bool $response_expected)

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

array BrickletBarometer::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 BrickletBarometer::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 BrickletBarometer::setAirPressureCallbackPeriod(int $period)

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

The CALLBACK_AIR_PRESSURE callback is only triggered if the air pressure has changed since the last triggering.

The default value is 0.

int BrickletBarometer::getAirPressureCallbackPeriod()

Returns the period as set by setAirPressureCallbackPeriod().

void BrickletBarometer::setAltitudeCallbackPeriod(int $period)

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

The CALLBACK_ALTITUDE callback is only triggered if the altitude has changed since the last triggering.

The default value is 0.

int BrickletBarometer::getAltitudeCallbackPeriod()

Returns the period as set by setAltitudeCallbackPeriod().

void BrickletBarometer::setAirPressureCallbackThreshold(string $option, int $min, int $max)

Sets the thresholds for the CALLBACK_AIR_PRESSURE_REACHED callback.

The following options are possible:

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

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

The following constants are available for this function:

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

Returns the threshold as set by setAirPressureCallbackThreshold().

The following constants are available for this function:

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

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

void BrickletBarometer::setAltitudeCallbackThreshold(string $option, int $min, int $max)

Sets the thresholds for the CALLBACK_ALTITUDE_REACHED callback.

The following options are possible:

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

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

The following constants are available for this function:

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

Returns the threshold as set by setAltitudeCallbackThreshold().

The following constants are available for this function:

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

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

void BrickletBarometer::setDebouncePeriod(int $debounce)

Sets the period in ms with which the threshold callbacks

are triggered, if the thresholds

keep being reached.

The default value is 100.

int BrickletBarometer::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";
}

$barometer->registerCallback(BrickletBarometer::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 BrickletBarometer::CALLBACK_AIR_PRESSURE
<?php   void callback(int $air_pressure [, mixed $user_data])   ?>

This callback is triggered periodically with the period that is set by setAirPressureCallbackPeriod(). The parameter is the air pressure of the air pressure sensor.

The CALLBACK_AIR_PRESSURE callback is only triggered if the air pressure has changed since the last triggering.

int BrickletBarometer::CALLBACK_ALTITUDE
<?php   void callback(int $altitude [, mixed $user_data])   ?>

This callback is triggered periodically with the period that is set by setAltitudeCallbackPeriod(). The parameter is the altitude of the air pressure sensor.

The CALLBACK_ALTITUDE callback is only triggered if the altitude has changed since the last triggering.

int BrickletBarometer::CALLBACK_AIR_PRESSURE_REACHED
<?php   void callback(int $air_pressure [, mixed $user_data])   ?>

This callback is triggered when the threshold as set by setAirPressureCallbackThreshold() is reached. The parameter is the air pressure of the air pressure sensor.

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

int BrickletBarometer::CALLBACK_ALTITUDE_REACHED
<?php   void callback(int $altitude [, mixed $user_data])   ?>

This callback is triggered when the threshold as set by setAltitudeCallbackThreshold() is reached. The parameter is the altitude of the air pressure sensor.

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

Constants

int BrickletBarometer::DEVICE_IDENTIFIER

This constant is used to identify a Barometer 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 BrickletBarometer::DEVICE_DISPLAY_NAME

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