PHP - Thermal Imaging Bricklet

This is the description of the PHP API bindings for the Thermal Imaging Bricklet. General information and technical specifications for the Thermal Imaging 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).

Callback

Download (ExampleCallback.php)

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<?php

require_once('Tinkerforge/IPConnection.php');
require_once('Tinkerforge/BrickletThermalImaging.php');

use Tinkerforge\IPConnection;
use Tinkerforge\BrickletThermalImaging;

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

// Callback function for high contrast image callback
function cb_highContrastImage($image)
{
    // $image is a array of size 80*60 with 8 bit grey value for each element
}

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

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

// Register high contrast image callback to function cb_highContrastImage
$ti->registerCallback(BrickletThermalImaging::CALLBACK_HIGH_CONTRAST_IMAGE,
                      'cb_highContrastImage');

// Enable high contrast image transfer for callback
$ti->setImageTransferConfig(BrickletThermalImaging::IMAGE_TRANSFER_CALLBACK_HIGH_CONTRAST_IMAGE);

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 BrickletThermalImaging(string $uid, IPConnection $ipcon)

Creates an object with the unique device ID $uid:

<?php   $thermal_imaging = new BrickletThermalImaging('YOUR_DEVICE_UID', $ipcon);   ?>

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

array BrickletThermalImaging::getHighContrastImage()

Returns the current high contrast image. See here for the difference between High Contrast and Temperature Image. If you don't know what to use the High Contrast Image is probably right for you.

The data is organized as a 8-bit value 80x60 pixel matrix linearized in a one-dimensional array. The data is arranged line by line from top left to bottom right.

Each 8-bit value represents one gray-scale image pixel that can directly be shown to a user on a display.

Before you can use this function you have to enable it with setImageTransferConfig().

array BrickletThermalImaging::getTemperatureImage()

Returns the current temperature image. See here for the difference between High Contrast and Temperature Image. If you don't know what to use the High Contrast Image is probably right for you.

The data is organized as a 16-bit value 80x60 pixel matrix linearized in a one-dimensional array. The data is arranged line by line from top left to bottom right.

Each 16-bit value represents one temperature measurement in either Kelvin/10 or Kelvin/100 (depending on the resolution set with:php:func:setResolution() <BrickletThermalImaging::setResolution>).

Before you can use this function you have to enable it with setImageTransferConfig().

array BrickletThermalImaging::getStatistics()

Returns the spotmeter statistics, various temperatures, current resolution and status bits.

The spotmeter statistics are:

  • Index 0: Mean Temperature.
  • Index 1: Maximum Temperature.
  • Index 2: Minimum Temperature.
  • Index 3: Pixel Count of spotmeter region of interest.

The temperatures are:

  • Index 0: Focal Plain Array temperature.
  • Index 1: Focal Plain Array temperature at last FFC (Flat Field Correction).
  • Index 2: Housing temperature.
  • Index 3: Housing temperature at last FFC.

The resolution is either 0 to 6553 Kelvin or 0 to 655 Kelvin. If the resolution is the former, the temperatures are in Kelvin/10, if it is the latter the temperatures are in Kelvin/100.

FFC (Flat Field Correction) Status:

  • FFC Never Commanded: Only seen on startup before first FFC.
  • FFC Imminent: This state is entered 2 seconds prior to initiating FFC.
  • FFC In Progress: Flat field correction is started (shutter moves in front of lens and back). Takes about 1 second.
  • FFC Complete: Shutter is in waiting position again, FFC done.

Temperature warning bits:

  • Index 0: Shutter lockout (if true shutter is locked out because temperature is outside -10°C to +65°C)
  • Index 1: Overtemperature shut down imminent (goes true 10 seconds before shutdown)

The following constants are available for this function:

  • BrickletThermalImaging::RESOLUTION_0_TO_6553_KELVIN = 0
  • BrickletThermalImaging::RESOLUTION_0_TO_655_KELVIN = 1
  • BrickletThermalImaging::FFC_STATUS_NEVER_COMMANDED = 0
  • BrickletThermalImaging::FFC_STATUS_IMMINENT = 1
  • BrickletThermalImaging::FFC_STATUS_IN_PROGRESS = 2
  • BrickletThermalImaging::FFC_STATUS_COMPLETE = 3

The returned array has the keys spotmeter_statistics, temperatures, resolution, ffc_status and temperature_warning.

void BrickletThermalImaging::setResolution(int $resolution)

Sets the resolution. The Thermal Imaging Bricklet can either measure

  • from 0 to 6553 Kelvin (-273.15°C to +6279.85°C) with 0.1°C resolution or
  • from 0 to 655 Kelvin (-273.15°C to +381.85°C) with 0.01°C resolution.

The accuracy is specified for -10°C to 450°C in the first range and -10°C and 140°C in the second range.

The default value is 0 to 655 Kelvin.

The following constants are available for this function:

  • BrickletThermalImaging::RESOLUTION_0_TO_6553_KELVIN = 0
  • BrickletThermalImaging::RESOLUTION_0_TO_655_KELVIN = 1
int BrickletThermalImaging::getResolution()

Returns the resolution as set by setResolution().

The following constants are available for this function:

  • BrickletThermalImaging::RESOLUTION_0_TO_6553_KELVIN = 0
  • BrickletThermalImaging::RESOLUTION_0_TO_655_KELVIN = 1
void BrickletThermalImaging::setSpotmeterConfig(array $region_of_interest)

Sets the spotmeter region of interest. The 4 values are

  • Index 0: Column start (has to be smaller then Column end).
  • Index 1: Row start (has to be smaller then Row end).
  • Index 2: Column end (has to be smaller then 80).
  • Index 3: Row end (has to be smaller then 60).

The spotmeter statistics can be read out with getStatistics().

The default region of interest is (39, 29, 40, 30).

array BrickletThermalImaging::getSpotmeterConfig()

Returns the spotmeter config as set by setSpotmeterConfig().

void BrickletThermalImaging::setHighContrastConfig(array $region_of_interest, int $dampening_factor, array $clip_limit, int $empty_counts)

Sets the high contrast region of interest, dampening factor, clip limit and empty counts. This config is only used in high contrast mode (see setImageTransferConfig()).

The high contrast region of interest consists of four values:

  • Index 0: Column start (has to be smaller or equal then Column end).
  • Index 1: Row start (has to be smaller then Row end).
  • Index 2: Column end (has to be smaller then 80).
  • Index 3: Row end (has to be smaller then 60).

The algorithm to generate the high contrast image is applied to this region.

Dampening Factor: This parameter is the amount of temporal dampening applied to the HEQ (history equalization) transformation function. An IIR filter of the form:

(N / 256) * previous + ((256 - N) / 256) * current

is applied, and the HEQ dampening factor represents the value N in the equation, i.e., a value that applies to the amount of influence the previous HEQ transformation function has on the current function. The lower the value of N the higher the influence of the current video frame whereas the higher the value of N the more influence the previous damped transfer function has.

Clip Limit Index 0 (AGC HEQ Clip Limit Low): This parameter defines an artificial population that is added to every non-empty histogram bin. In other words, if the Clip Limit Low is set to L, a bin with an actual population of X will have an effective population of L + X. Any empty bin that is nearby a populated bin will be given an artificial population of L. The effect of higher values is to provide a more linear transfer function; lower values provide a more non-linear (equalized) transfer function.

Clip Limit Index 1 (AGC HEQ Clip Limit High): This parameter defines the maximum number of pixels allowed to accumulate in any given histogram bin. Any additional pixels in a given bin are clipped. The effect of this parameter is to limit the influence of highly-populated bins on the resulting HEQ transformation function.

Empty Counts: This parameter specifies the maximum number of pixels in a bin that will be interpreted as an empty bin. Histogram bins with this number of pixels or less will be processed as an empty bin.

The default values are

  • Region Of Interest = (0, 0, 79, 59),
  • Dampening Factor = 64,
  • Clip Limit = (4800, 512) and
  • Empty Counts = 2.
array BrickletThermalImaging::getHighContrastConfig()

Returns the high contrast config as set by setHighContrastConfig().

The returned array has the keys region_of_interest, dampening_factor, clip_limit and empty_counts.

Advanced Functions

array BrickletThermalImaging::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 BrickletThermalImaging::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 BrickletThermalImaging::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:

  • BrickletThermalImaging::FUNCTION_SET_RESOLUTION = 4
  • BrickletThermalImaging::FUNCTION_SET_SPOTMETER_CONFIG = 6
  • BrickletThermalImaging::FUNCTION_SET_HIGH_CONTRAST_CONFIG = 8
  • BrickletThermalImaging::FUNCTION_SET_IMAGE_TRANSFER_CONFIG = 10
  • BrickletThermalImaging::FUNCTION_SET_WRITE_FIRMWARE_POINTER = 237
  • BrickletThermalImaging::FUNCTION_SET_STATUS_LED_CONFIG = 239
  • BrickletThermalImaging::FUNCTION_RESET = 243
  • BrickletThermalImaging::FUNCTION_WRITE_UID = 248
void BrickletThermalImaging::setResponseExpectedAll(bool $response_expected)

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

array BrickletThermalImaging::getSPITFPErrorCount()

Returns the error count for the communication between Brick and Bricklet.

The errors are divided into

  • ACK checksum errors,
  • message checksum errors,
  • framing errors and
  • overflow errors.

The errors counts are for errors that occur on the Bricklet side. All Bricks have a similar function that returns the errors on the Brick side.

The returned array has the keys error_count_ack_checksum, error_count_message_checksum, error_count_frame and error_count_overflow.

int BrickletThermalImaging::setBootloaderMode(int $mode)

Sets the bootloader mode and returns the status after the requested mode change was instigated.

You can change from bootloader mode to firmware mode and vice versa. A change from bootloader mode to firmware mode will only take place if the entry function, device identifier and CRC are present and correct.

This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.

The following constants are available for this function:

  • BrickletThermalImaging::BOOTLOADER_MODE_BOOTLOADER = 0
  • BrickletThermalImaging::BOOTLOADER_MODE_FIRMWARE = 1
  • BrickletThermalImaging::BOOTLOADER_MODE_BOOTLOADER_WAIT_FOR_REBOOT = 2
  • BrickletThermalImaging::BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_REBOOT = 3
  • BrickletThermalImaging::BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_ERASE_AND_REBOOT = 4
  • BrickletThermalImaging::BOOTLOADER_STATUS_OK = 0
  • BrickletThermalImaging::BOOTLOADER_STATUS_INVALID_MODE = 1
  • BrickletThermalImaging::BOOTLOADER_STATUS_NO_CHANGE = 2
  • BrickletThermalImaging::BOOTLOADER_STATUS_ENTRY_FUNCTION_NOT_PRESENT = 3
  • BrickletThermalImaging::BOOTLOADER_STATUS_DEVICE_IDENTIFIER_INCORRECT = 4
  • BrickletThermalImaging::BOOTLOADER_STATUS_CRC_MISMATCH = 5
int BrickletThermalImaging::getBootloaderMode()

Returns the current bootloader mode, see setBootloaderMode().

The following constants are available for this function:

  • BrickletThermalImaging::BOOTLOADER_MODE_BOOTLOADER = 0
  • BrickletThermalImaging::BOOTLOADER_MODE_FIRMWARE = 1
  • BrickletThermalImaging::BOOTLOADER_MODE_BOOTLOADER_WAIT_FOR_REBOOT = 2
  • BrickletThermalImaging::BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_REBOOT = 3
  • BrickletThermalImaging::BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_ERASE_AND_REBOOT = 4
void BrickletThermalImaging::setWriteFirmwarePointer(int $pointer)

Sets the firmware pointer for writeFirmware(). The pointer has to be increased by chunks of size 64. The data is written to flash every 4 chunks (which equals to one page of size 256).

This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.

int BrickletThermalImaging::writeFirmware(array $data)

Writes 64 Bytes of firmware at the position as written by setWriteFirmwarePointer() before. The firmware is written to flash every 4 chunks.

You can only write firmware in bootloader mode.

This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.

void BrickletThermalImaging::setStatusLEDConfig(int $config)

Sets the status LED configuration. By default the LED shows communication traffic between Brick and Bricklet, it flickers once for every 10 received data packets.

You can also turn the LED permanently on/off or show a heartbeat.

If the Bricklet is in bootloader mode, the LED is will show heartbeat by default.

The following constants are available for this function:

  • BrickletThermalImaging::STATUS_LED_CONFIG_OFF = 0
  • BrickletThermalImaging::STATUS_LED_CONFIG_ON = 1
  • BrickletThermalImaging::STATUS_LED_CONFIG_SHOW_HEARTBEAT = 2
  • BrickletThermalImaging::STATUS_LED_CONFIG_SHOW_STATUS = 3
int BrickletThermalImaging::getStatusLEDConfig()

Returns the configuration as set by setStatusLEDConfig()

The following constants are available for this function:

  • BrickletThermalImaging::STATUS_LED_CONFIG_OFF = 0
  • BrickletThermalImaging::STATUS_LED_CONFIG_ON = 1
  • BrickletThermalImaging::STATUS_LED_CONFIG_SHOW_HEARTBEAT = 2
  • BrickletThermalImaging::STATUS_LED_CONFIG_SHOW_STATUS = 3
int BrickletThermalImaging::getChipTemperature()

Returns the temperature in °C as measured inside the microcontroller. The value returned is not the ambient temperature!

The temperature is only proportional to the real temperature and it has bad accuracy. Practically it is only useful as an indicator for temperature changes.

void BrickletThermalImaging::reset()

Calling this function will reset the Bricklet. All configurations will be lost.

After a reset you have to create new device objects, calling functions on the existing ones will result in undefined behavior!

void BrickletThermalImaging::writeUID(int $uid)

Writes a new UID into flash. If you want to set a new UID you have to decode the Base58 encoded UID string into an integer first.

We recommend that you use Brick Viewer to change the UID.

int BrickletThermalImaging::readUID()

Returns the current UID as an integer. Encode as Base58 to get the usual string version.

array BrickletThermalImaging::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 BrickletThermalImaging::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 BrickletThermalImaging::setImageTransferConfig(int $config)

The necessary bandwidth of this Bricklet is too high to use getter/callback or high contrast/temperature image at the same time. You have to configure the one you want to use, the Bricklet will optimize the internal configuration accordingly.

Corresponding functions:

The default is Manual High Contrast Image (0).

The following constants are available for this function:

  • BrickletThermalImaging::IMAGE_TRANSFER_MANUAL_HIGH_CONTRAST_IMAGE = 0
  • BrickletThermalImaging::IMAGE_TRANSFER_MANUAL_TEMPERATURE_IMAGE = 1
  • BrickletThermalImaging::IMAGE_TRANSFER_CALLBACK_HIGH_CONTRAST_IMAGE = 2
  • BrickletThermalImaging::IMAGE_TRANSFER_CALLBACK_TEMPERATURE_IMAGE = 3
int BrickletThermalImaging::getImageTransferConfig()

Returns the image transfer config, as set by setImageTransferConfig().

The following constants are available for this function:

  • BrickletThermalImaging::IMAGE_TRANSFER_MANUAL_HIGH_CONTRAST_IMAGE = 0
  • BrickletThermalImaging::IMAGE_TRANSFER_MANUAL_TEMPERATURE_IMAGE = 1
  • BrickletThermalImaging::IMAGE_TRANSFER_CALLBACK_HIGH_CONTRAST_IMAGE = 2
  • BrickletThermalImaging::IMAGE_TRANSFER_CALLBACK_TEMPERATURE_IMAGE = 3

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";
}

$thermal_imaging->registerCallback(BrickletThermalImaging::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 BrickletThermalImaging::CALLBACK_HIGH_CONTRAST_IMAGE
<?php   void callback(array $image [, mixed $user_data])   ?>

This callback is triggered with every new high contrast image if the transfer image config is configured for high contrast callback (see setImageTransferConfig()).

The data is organized as a 8-bit value 80x60 pixel matrix linearized in a one-dimensional array. The data is arranged line by line from top left to bottom right.

Each 8-bit value represents one gray-scale image pixel that can directly be shown to a user on a display.

int BrickletThermalImaging::CALLBACK_TEMPERATURE_IMAGE
<?php   void callback(array $image [, mixed $user_data])   ?>

This callback is triggered with every new temperature image if the transfer image config is configured for temperature callback (see setImageTransferConfig()).

The data is organized as a 16-bit value 80x60 pixel matrix linearized in a one-dimensional array. The data is arranged line by line from top left to bottom right.

Each 16-bit value represents one temperature measurement in either Kelvin/10 or Kelvin/100 (depending on the resolution set with setResolution()).

Constants

int BrickletThermalImaging::DEVICE_IDENTIFIER

This constant is used to identify a Thermal Imaging 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 BrickletThermalImaging::DEVICE_DISPLAY_NAME

This constant represents the human readable name of a Thermal Imaging Bricklet.