PHP - CO2 Bricklet

This is the description of the PHP API bindings for the CO2 Bricklet. General information and technical specifications for the CO2 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/BrickletCO2.php');

use Tinkerforge\IPConnection;
use Tinkerforge\BrickletCO2;

const HOST = 'localhost';
const PORT = 4223;
const UID = 'XYZ'; // Change XYZ to the UID of your CO2 Bricklet

$ipcon = new IPConnection(); // Create IP connection
$co2 = new BrickletCO2(UID, $ipcon); // Create device object

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

// Get current CO2 concentration
$co2_concentration = $co2->getCO2Concentration();
echo "CO2 Concentration: $co2_concentration ppm\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/BrickletCO2.php');

use Tinkerforge\IPConnection;
use Tinkerforge\BrickletCO2;

const HOST = 'localhost';
const PORT = 4223;
const UID = 'XYZ'; // Change XYZ to the UID of your CO2 Bricklet

// Callback function for CO2 concentration callback
function cb_co2Concentration($co2_concentration)
{
    echo "CO2 Concentration: $co2_concentration ppm\n";
}

$ipcon = new IPConnection(); // Create IP connection
$co2 = new BrickletCO2(UID, $ipcon); // Create device object

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

// Register CO2 concentration callback to function cb_co2Concentration
$co2->registerCallback(BrickletCO2::CALLBACK_CO2_CONCENTRATION, 'cb_co2Concentration');

// Set period for CO2 concentration callback to 1s (1000ms)
// Note: The CO2 concentration callback is only called every second
//       if the CO2 concentration has changed since the last call!
$co2->setCO2ConcentrationCallbackPeriod(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/BrickletCO2.php');

use Tinkerforge\IPConnection;
use Tinkerforge\BrickletCO2;

const HOST = 'localhost';
const PORT = 4223;
const UID = 'XYZ'; // Change XYZ to the UID of your CO2 Bricklet

// Callback function for CO2 concentration reached callback
function cb_co2ConcentrationReached($co2_concentration)
{
    echo "CO2 Concentration: $co2_concentration ppm\n";
}

$ipcon = new IPConnection(); // Create IP connection
$co2 = new BrickletCO2(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)
$co2->setDebouncePeriod(10000);

// Register CO2 concentration reached callback to function cb_co2ConcentrationReached
$co2->registerCallback(BrickletCO2::CALLBACK_CO2_CONCENTRATION_REACHED,
                       'cb_co2ConcentrationReached');

// Configure threshold for CO2 concentration "greater than 750 ppm"
$co2->setCO2ConcentrationCallbackThreshold('>', 750, 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 BrickletCO2(string $uid, IPConnection $ipcon)

Creates an object with the unique device ID $uid:

<?php   $co2 = new BrickletCO2('YOUR_DEVICE_UID', $ipcon);   ?>

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

int BrickletCO2::getCO2Concentration()

Returns the measured CO2 concentration. The value is in ppm (parts per million) and between 0 to 10000.

If you want to get the CO2 concentration periodically, it is recommended to use the CALLBACK_CO2_CONCENTRATION callback and set the period with setCO2ConcentrationCallbackPeriod().

Advanced Functions

array BrickletCO2::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 BrickletCO2::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 BrickletCO2::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:

  • BrickletCO2::FUNCTION_SET_CO2_CONCENTRATION_CALLBACK_PERIOD = 2
  • BrickletCO2::FUNCTION_SET_CO2_CONCENTRATION_CALLBACK_THRESHOLD = 4
  • BrickletCO2::FUNCTION_SET_DEBOUNCE_PERIOD = 6
void BrickletCO2::setResponseExpectedAll(bool $response_expected)

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

array BrickletCO2::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 BrickletCO2::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 BrickletCO2::setCO2ConcentrationCallbackPeriod(int $period)

Sets the period in ms with which the CALLBACK_CO2_CONCENTRATION callback is triggered periodically. A value of 0 turns the callback off.

The CALLBACK_CO2_CONCENTRATION callback is only triggered if the CO2 concentration has changed since the last triggering.

The default value is 0.

int BrickletCO2::getCO2ConcentrationCallbackPeriod()

Returns the period as set by setCO2ConcentrationCallbackPeriod().

void BrickletCO2::setCO2ConcentrationCallbackThreshold(string $option, int $min, int $max)

Sets the thresholds for the CALLBACK_CO2_CONCENTRATION_REACHED callback.

The following options are possible:

Option Description
'x' Callback is turned off
'o' Callback is triggered when the CO2 concentration is outside the min and max values
'i' Callback is triggered when the CO2 concentration is inside the min and max values
'<' Callback is triggered when the CO2 concentration is smaller than the min value (max is ignored)
'>' Callback is triggered when the CO2 concentration is greater than the min value (max is ignored)

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

The following constants are available for this function:

  • BrickletCO2::THRESHOLD_OPTION_OFF = 'x'
  • BrickletCO2::THRESHOLD_OPTION_OUTSIDE = 'o'
  • BrickletCO2::THRESHOLD_OPTION_INSIDE = 'i'
  • BrickletCO2::THRESHOLD_OPTION_SMALLER = '<'
  • BrickletCO2::THRESHOLD_OPTION_GREATER = '>'
array BrickletCO2::getCO2ConcentrationCallbackThreshold()

Returns the threshold as set by setCO2ConcentrationCallbackThreshold().

The following constants are available for this function:

  • BrickletCO2::THRESHOLD_OPTION_OFF = 'x'
  • BrickletCO2::THRESHOLD_OPTION_OUTSIDE = 'o'
  • BrickletCO2::THRESHOLD_OPTION_INSIDE = 'i'
  • BrickletCO2::THRESHOLD_OPTION_SMALLER = '<'
  • BrickletCO2::THRESHOLD_OPTION_GREATER = '>'

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

void BrickletCO2::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 BrickletCO2::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";
}

$co2->registerCallback(BrickletCO2::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 BrickletCO2::CALLBACK_CO2_CONCENTRATION
<?php   void callback(int $co2_concentration [, mixed $user_data])   ?>

This callback is triggered periodically with the period that is set by setCO2ConcentrationCallbackPeriod(). The parameter is the CO2 concentration of the sensor.

The CALLBACK_CO2_CONCENTRATION callback is only triggered if the CO2 concentration has changed since the last triggering.

int BrickletCO2::CALLBACK_CO2_CONCENTRATION_REACHED
<?php   void callback(int $co2_concentration [, mixed $user_data])   ?>

This callback is triggered when the threshold as set by setCO2ConcentrationCallbackThreshold() is reached. The parameter is the CO2 concentration.

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

Constants

int BrickletCO2::DEVICE_IDENTIFIER

This constant is used to identify a CO2 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 BrickletCO2::DEVICE_DISPLAY_NAME

This constant represents the human readable name of a CO2 Bricklet.