PHP - Compass Bricklet

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

use Tinkerforge\IPConnection;
use Tinkerforge\BrickletCompass;

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

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

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

// Get current heading
$heading = $c->getHeading();
echo "Heading: " . $heading/10.0 . " °\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/BrickletCompass.php');

use Tinkerforge\IPConnection;
use Tinkerforge\BrickletCompass;

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

// Callback function for heading callback
function cb_heading($heading)
{
    echo "Heading: " . $heading/10.0 . " °\n";
}

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

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

// Register heading callback to function cb_heading
$c->registerCallback(BrickletCompass::CALLBACK_HEADING, 'cb_heading');

// Set period for heading callback to 0.1s (100ms) without a threshold
$c->setHeadingCallbackConfiguration(100, FALSE, 'x', 0, 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 BrickletCompass(string $uid, IPConnection $ipcon)

Creates an object with the unique device ID $uid:

<?php   $compass = new BrickletCompass('YOUR_DEVICE_UID', $ipcon);   ?>

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

int BrickletCompass::getHeading()

Returns the heading in 1/10 degree (north = 0 degree, east = 90 degree).

Alternatively you can use getMagneticFluxDensity() and calculate the heading with heading = atan2(y, x) * 180 / PI.

If you want to get the value periodically, it is recommended to use the CALLBACK_HEADING callback. You can set the callback configuration with setHeadingCallbackConfiguration().

array BrickletCompass::getMagneticFluxDensity()

Returns the magnetic flux density (magnetic induction) for all three axis in 1/10 mG (milli Gauss).

If you want to get the value periodically, it is recommended to use the CALLBACK_MAGNETIC_FLUX_DENSITY callback. You can set the callback configuration with setMagneticFluxDensityCallbackConfiguration().

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

void BrickletCompass::setConfiguration(int $data_rate, bool $background_calibration)

Configures the data rate and background calibration.

  • Data Rate: Sets the data rate that is used by the magnetometer. The lower the data rate, the lower is the noise on the data.
  • Background Calibration: Set to true to enable the background calibration and false to turn it off. If the background calibration is enabled the sensing polarity is flipped once per second to automatically calculate and remove offset that is caused by temperature changes. This polarity flipping takes about 20ms. This means that once a second you will not get new data for a period of 20ms. We highly recommend that you keep the background calibration enabled and only disable it if the 20ms off-time is a problem in your application.

Default values: Data rate of 100Hz and background calibration enabled.

The following constants are available for this function:

  • BrickletCompass::DATA_RATE_100HZ = 0
  • BrickletCompass::DATA_RATE_200HZ = 1
  • BrickletCompass::DATA_RATE_400HZ = 2
  • BrickletCompass::DATA_RATE_600HZ = 3
array BrickletCompass::getConfiguration()

Returns the configuration as set by setConfiguration().

The following constants are available for this function:

  • BrickletCompass::DATA_RATE_100HZ = 0
  • BrickletCompass::DATA_RATE_200HZ = 1
  • BrickletCompass::DATA_RATE_400HZ = 2
  • BrickletCompass::DATA_RATE_600HZ = 3

The returned array has the keys data_rate and background_calibration.

Advanced Functions

void BrickletCompass::setCalibration(array $offset, array $gain)

Sets offset and gain for each of the three axes.

The Bricklet is factory calibrated. If you want to re-calibrate the Bricklet we recommend that you do the calibration through Brick Viewer.

The calibration is saved in non-volatile memory and only has to be done once.

array BrickletCompass::getCalibration()

Returns the calibration parameters as set by setCalibration().

The returned array has the keys offset and gain.

array BrickletCompass::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 BrickletCompass::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.

The following constants are available for this function:

  • BrickletCompass::FUNCTION_SET_HEADING_CALLBACK_CONFIGURATION = 2
  • BrickletCompass::FUNCTION_SET_MAGNETIC_FLUX_DENSITY_CALLBACK_CONFIGURATION = 6
  • BrickletCompass::FUNCTION_SET_CONFIGURATION = 9
  • BrickletCompass::FUNCTION_SET_CALIBRATION = 11
  • BrickletCompass::FUNCTION_SET_WRITE_FIRMWARE_POINTER = 237
  • BrickletCompass::FUNCTION_SET_STATUS_LED_CONFIG = 239
  • BrickletCompass::FUNCTION_RESET = 243
  • BrickletCompass::FUNCTION_WRITE_UID = 248
void BrickletCompass::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 constants are available for this function:

  • BrickletCompass::FUNCTION_SET_HEADING_CALLBACK_CONFIGURATION = 2
  • BrickletCompass::FUNCTION_SET_MAGNETIC_FLUX_DENSITY_CALLBACK_CONFIGURATION = 6
  • BrickletCompass::FUNCTION_SET_CONFIGURATION = 9
  • BrickletCompass::FUNCTION_SET_CALIBRATION = 11
  • BrickletCompass::FUNCTION_SET_WRITE_FIRMWARE_POINTER = 237
  • BrickletCompass::FUNCTION_SET_STATUS_LED_CONFIG = 239
  • BrickletCompass::FUNCTION_RESET = 243
  • BrickletCompass::FUNCTION_WRITE_UID = 248
void BrickletCompass::setResponseExpectedAll(bool $response_expected)

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

array BrickletCompass::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 BrickletCompass::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:

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

Returns the current bootloader mode, see setBootloaderMode().

The following constants are available for this function:

  • BrickletCompass::BOOTLOADER_MODE_BOOTLOADER = 0
  • BrickletCompass::BOOTLOADER_MODE_FIRMWARE = 1
  • BrickletCompass::BOOTLOADER_MODE_BOOTLOADER_WAIT_FOR_REBOOT = 2
  • BrickletCompass::BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_REBOOT = 3
  • BrickletCompass::BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_ERASE_AND_REBOOT = 4
void BrickletCompass::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 BrickletCompass::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 BrickletCompass::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:

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

Returns the configuration as set by setStatusLEDConfig()

The following constants are available for this function:

  • BrickletCompass::STATUS_LED_CONFIG_OFF = 0
  • BrickletCompass::STATUS_LED_CONFIG_ON = 1
  • BrickletCompass::STATUS_LED_CONFIG_SHOW_HEARTBEAT = 2
  • BrickletCompass::STATUS_LED_CONFIG_SHOW_STATUS = 3
int BrickletCompass::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 BrickletCompass::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 BrickletCompass::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 BrickletCompass::readUID()

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

array BrickletCompass::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 BrickletCompass::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 BrickletCompass::setHeadingCallbackConfiguration(int $period, bool $value_has_to_change, string $option, int $min, int $max)

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

If the value has to change-parameter is set to true, the callback is only triggered after the value has changed. If the value didn't change within the period, the callback is triggered immediately on change.

If it is set to false, the callback is continuously triggered with the period, independent of the value.

It is furthermore possible to constrain the callback with thresholds.

The option-parameter together with min/max sets a threshold for the CALLBACK_HEADING callback.

The following options are possible:

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

If the option is set to 'x' (threshold turned off) the callback is triggered with the fixed period.

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

The following constants are available for this function:

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

Returns the callback configuration as set by setHeadingCallbackConfiguration().

The following constants are available for this function:

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

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

void BrickletCompass::setMagneticFluxDensityCallbackConfiguration(int $period, bool $value_has_to_change)

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

If the value has to change-parameter is set to true, the callback is only triggered after the value has changed. If the value didn't change within the period, the callback is triggered immediately on change.

If it is set to false, the callback is continuously triggered with the period, independent of the value.

The default value is (0, false).

array BrickletCompass::getMagneticFluxDensityCallbackConfiguration()

Returns the callback configuration as set by setMagneticFluxDensityCallbackConfiguration().

The returned array has the keys period and value_has_to_change.

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";
}

$compass->registerCallback(BrickletCompass::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 BrickletCompass::CALLBACK_HEADING
<?php   void callback(int $heading [, mixed $user_data])   ?>

This callback is triggered periodically according to the configuration set by setHeadingCallbackConfiguration().

The parameter is the same as getHeading().

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

This callback is triggered periodically according to the configuration set by setMagneticFluxDensityCallbackConfiguration().

The parameters are the same as getMagneticFluxDensity().

Constants

int BrickletCompass::DEVICE_IDENTIFIER

This constant is used to identify a Compass 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 BrickletCompass::DEVICE_DISPLAY_NAME

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