PHP - Stepper Brick

This is the description of the PHP API bindings for the Stepper Brick. General information and technical specifications for the Stepper Brick 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).

Configuration

Download (ExampleConfiguration.php)

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<?php

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

use Tinkerforge\IPConnection;
use Tinkerforge\BrickStepper;

const HOST = 'localhost';
const PORT = 4223;
const UID = 'XXYYZZ'; // Change XXYYZZ to the UID of your Stepper Brick

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

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

$stepper->setMotorCurrent(800); // 800mA
$stepper->setStepMode(8); // 1/8 step mode
$stepper->setMaxVelocity(2000); // Velocity 2000 steps/s

// Slow acceleration (500 steps/s^2),
// Fast deacceleration (5000 steps/s^2)
$stepper->setSpeedRamping(500, 5000);

$stepper->enable(); // Enable motor power
$stepper->setSteps(60000); // Drive 60000 steps forward

echo "Press key to exit\n";
fgetc(fopen('php://stdin', 'r'));
$stepper->disable();
$ipcon->disconnect();

?>

Callback

Download (ExampleCallback.php)

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<?php

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

use Tinkerforge\IPConnection;
use Tinkerforge\BrickStepper;

const HOST = 'localhost';
const PORT = 4223;
const UID = 'XXYYZZ'; // Change XXYYZZ to the UID of your Stepper Brick

// Use position reached callback to program random movement
function cb_positionReached($position, $user_data)
{
    $stepper = $user_data;

    if (rand(0, 1)) {
        $steps = rand(1000, 5000); // steps (forward)
        echo "Driving forward: $steps steps\n";
    } else {
        $steps = rand(-5000, -1000); // steps (backward)
        echo "Driving backward: $steps steps\n";
    }

    $vel = rand(200, 2000); // steps/s
    $acc = rand(100, 1000); // steps/s^2
    $dec = rand(100, 1000); // steps/s^2
    echo "Configuration (vel, acc, dec): $vel, $acc, $dec\n";

    $stepper->setSpeedRamping($acc, $dec);
    $stepper->setMaxVelocity($vel);
    $stepper->setSteps($steps);
}

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

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

// Register position reached callback to function cb_positionReached
$stepper->registerCallback(BrickStepper::CALLBACK_POSITION_REACHED,
                           'cb_positionReached', $stepper);

$stepper->enable(); // Enable motor power
$stepper->setSteps(1); // Drive one step forward to get things going

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 BrickStepper(string $uid, IPConnection $ipcon)

Creates an object with the unique device ID $uid:

<?php   $stepper = new BrickStepper('YOUR_DEVICE_UID', $ipcon);   ?>

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

void BrickStepper::setMaxVelocity(int $velocity)

Sets the maximum velocity of the stepper motor in steps per second. This function does not start the motor, it merely sets the maximum velocity the stepper motor is accelerated to. To get the motor running use either setTargetPosition(), setSteps(), driveForward() or driveBackward().

int BrickStepper::getMaxVelocity()

Returns the velocity as set by setMaxVelocity().

int BrickStepper::getCurrentVelocity()

Returns the current velocity of the stepper motor in steps per second.

void BrickStepper::setSpeedRamping(int $acceleration, int $deacceleration)

Sets the acceleration and deacceleration of the stepper motor. The values are given in steps/s². An acceleration of 1000 means, that every second the velocity is increased by 1000 steps/s.

For example: If the current velocity is 0 and you want to accelerate to a velocity of 8000 steps/s in 10 seconds, you should set an acceleration of 800 steps/s².

An acceleration/deacceleration of 0 means instantaneous acceleration/deacceleration (not recommended)

The default value is 1000 for both

array BrickStepper::getSpeedRamping()

Returns the acceleration and deacceleration as set by setSpeedRamping().

The returned array has the keys acceleration and deacceleration.

void BrickStepper::fullBrake()

Executes an active full brake.

Warning

This function is for emergency purposes, where an immediate brake is necessary. Depending on the current velocity and the strength of the motor, a full brake can be quite violent.

Call stop() if you just want to stop the motor.

void BrickStepper::setSteps(int $steps)

Sets the number of steps the stepper motor should run. Positive values will drive the motor forward and negative values backward. The velocity, acceleration and deacceleration as set by setMaxVelocity() and setSpeedRamping() will be used.

int BrickStepper::getSteps()

Returns the last steps as set by setSteps().

int BrickStepper::getRemainingSteps()

Returns the remaining steps of the last call of setSteps(). For example, if setSteps() is called with 2000 and getRemainingSteps() is called after the motor has run for 500 steps, it will return 1500.

void BrickStepper::driveForward()

Drives the stepper motor forward until driveBackward() or stop() is called. The velocity, acceleration and deacceleration as set by setMaxVelocity() and setSpeedRamping() will be used.

void BrickStepper::driveBackward()

Drives the stepper motor backward until driveForward() or stop() is triggered. The velocity, acceleration and deacceleration as set by setMaxVelocity() and setSpeedRamping() will be used.

void BrickStepper::stop()

Stops the stepper motor with the deacceleration as set by setSpeedRamping().

void BrickStepper::setMotorCurrent(int $current)

Sets the current in mA with which the motor will be driven. The minimum value is 100mA, the maximum value 2291mA and the default value is 800mA.

Warning

Do not set this value above the specifications of your stepper motor. Otherwise it may damage your motor.

int BrickStepper::getMotorCurrent()

Returns the current as set by setMotorCurrent().

void BrickStepper::enable()

Enables the driver chip. The driver parameters can be configured (maximum velocity, acceleration, etc) before it is enabled.

void BrickStepper::disable()

Disables the driver chip. The configurations are kept (maximum velocity, acceleration, etc) but the motor is not driven until it is enabled again.

bool BrickStepper::isEnabled()

Returns true if the driver chip is enabled, false otherwise.

Advanced Functions

void BrickStepper::setCurrentPosition(int $position)

Sets the current steps of the internal step counter. This can be used to set the current position to 0 when some kind of starting position is reached (e.g. when a CNC machine reaches a corner).

int BrickStepper::getCurrentPosition()

Returns the current position of the stepper motor in steps. On startup the position is 0. The steps are counted with all possible driving functions (setTargetPosition(), setSteps(), driveForward() or driveBackward()). It also is possible to reset the steps to 0 or set them to any other desired value with setCurrentPosition().

void BrickStepper::setTargetPosition(int $position)

Sets the target position of the stepper motor in steps. For example, if the current position of the motor is 500 and setTargetPosition() is called with 1000, the stepper motor will drive 500 steps forward. It will use the velocity, acceleration and deacceleration as set by setMaxVelocity() and setSpeedRamping().

A call of setTargetPosition() with the parameter x is equivalent to a call of setSteps() with the parameter (x - getCurrentPosition()).

int BrickStepper::getTargetPosition()

Returns the last target position as set by setTargetPosition().

void BrickStepper::setStepMode(int $mode)

Sets the step mode of the stepper motor. Possible values are:

  • Full Step = 1
  • Half Step = 2
  • Quarter Step = 4
  • Eighth Step = 8

A higher value will increase the resolution and decrease the torque of the stepper motor.

The default value is 8 (Eighth Step).

The following constants are available for this function:

  • BrickStepper::STEP_MODE_FULL_STEP = 1
  • BrickStepper::STEP_MODE_HALF_STEP = 2
  • BrickStepper::STEP_MODE_QUARTER_STEP = 4
  • BrickStepper::STEP_MODE_EIGHTH_STEP = 8
int BrickStepper::getStepMode()

Returns the step mode as set by setStepMode().

The following constants are available for this function:

  • BrickStepper::STEP_MODE_FULL_STEP = 1
  • BrickStepper::STEP_MODE_HALF_STEP = 2
  • BrickStepper::STEP_MODE_QUARTER_STEP = 4
  • BrickStepper::STEP_MODE_EIGHTH_STEP = 8
int BrickStepper::getStackInputVoltage()

Returns the stack input voltage in mV. The stack input voltage is the voltage that is supplied via the stack, i.e. it is given by a Step-Down or Step-Up Power Supply.

int BrickStepper::getExternalInputVoltage()

Returns the external input voltage in mV. The external input voltage is given via the black power input connector on the Stepper Brick.

If there is an external input voltage and a stack input voltage, the motor will be driven by the external input voltage. If there is only a stack voltage present, the motor will be driven by this voltage.

Warning

This means, if you have a high stack voltage and a low external voltage, the motor will be driven with the low external voltage. If you then remove the external connection, it will immediately be driven by the high stack voltage

int BrickStepper::getCurrentConsumption()

Returns the current consumption of the motor in mA.

void BrickStepper::setDecay(int $decay)

Sets the decay mode of the stepper motor. The possible value range is between 0 and 65535. A value of 0 sets the fast decay mode, a value of 65535 sets the slow decay mode and a value in between sets the mixed decay mode.

Changing the decay mode is only possible if synchronous rectification is enabled (see setSyncRect()).

For a good explanation of the different decay modes see this blog post by Avayan.

A good decay mode is unfortunately different for every motor. The best way to work out a good decay mode for your stepper motor, if you can't measure the current with an oscilloscope, is to listen to the sound of the motor. If the value is too low, you often hear a high pitched sound and if it is too high you can often hear a humming sound.

Generally, fast decay mode (small value) will be noisier but also allow higher motor speeds.

The default value is 10000.

Note

There is unfortunately no formula to calculate a perfect decay mode for a given stepper motor. If you have problems with loud noises or the maximum motor speed is too slow, you should try to tinker with the decay value

int BrickStepper::getDecay()

Returns the decay mode as set by setDecay().

void BrickStepper::setSyncRect(bool $sync_rect)

Turns synchronous rectification on or off (true or false).

With synchronous rectification on, the decay can be changed (see setDecay()). Without synchronous rectification fast decay is used.

For an explanation of synchronous rectification see here.

Warning

If you want to use high speeds (> 10000 steps/s) for a large stepper motor with a large inductivity we strongly suggest that you disable synchronous rectification. Otherwise the Brick may not be able to cope with the load and overheat.

The default value is false.

bool BrickStepper::isSyncRect()

Returns true if synchronous rectification is enabled, false otherwise.

void BrickStepper::setTimeBase(int $time_base)

Sets the time base of the velocity and the acceleration of the stepper brick (in seconds).

For example, if you want to make one step every 1.5 seconds, you can set the time base to 15 and the velocity to 10. Now the velocity is 10steps/15s = 1steps/1.5s.

The default value is 1.

int BrickStepper::getTimeBase()

Returns the time base as set by setTimeBase().

array BrickStepper::getAllData()

Returns the following parameters: The current velocity, the current position, the remaining steps, the stack voltage, the external voltage and the current consumption of the stepper motor.

There is also a callback for this function, see CALLBACK_ALL_DATA callback.

The returned array has the keys current_velocity, current_position, remaining_steps, stack_voltage, external_voltage and current_consumption.

array BrickStepper::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 BrickStepper::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 BrickStepper::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:

  • BrickStepper::FUNCTION_SET_MAX_VELOCITY = 1
  • BrickStepper::FUNCTION_SET_SPEED_RAMPING = 4
  • BrickStepper::FUNCTION_FULL_BRAKE = 6
  • BrickStepper::FUNCTION_SET_CURRENT_POSITION = 7
  • BrickStepper::FUNCTION_SET_TARGET_POSITION = 9
  • BrickStepper::FUNCTION_SET_STEPS = 11
  • BrickStepper::FUNCTION_SET_STEP_MODE = 14
  • BrickStepper::FUNCTION_DRIVE_FORWARD = 16
  • BrickStepper::FUNCTION_DRIVE_BACKWARD = 17
  • BrickStepper::FUNCTION_STOP = 18
  • BrickStepper::FUNCTION_SET_MOTOR_CURRENT = 22
  • BrickStepper::FUNCTION_ENABLE = 24
  • BrickStepper::FUNCTION_DISABLE = 25
  • BrickStepper::FUNCTION_SET_DECAY = 27
  • BrickStepper::FUNCTION_SET_MINIMUM_VOLTAGE = 29
  • BrickStepper::FUNCTION_SET_SYNC_RECT = 33
  • BrickStepper::FUNCTION_SET_TIME_BASE = 35
  • BrickStepper::FUNCTION_SET_ALL_DATA_PERIOD = 38
  • BrickStepper::FUNCTION_SET_SPITFP_BAUDRATE_CONFIG = 231
  • BrickStepper::FUNCTION_SET_SPITFP_BAUDRATE = 234
  • BrickStepper::FUNCTION_ENABLE_STATUS_LED = 238
  • BrickStepper::FUNCTION_DISABLE_STATUS_LED = 239
  • BrickStepper::FUNCTION_RESET = 243
void BrickStepper::setResponseExpectedAll(bool $response_expected)

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

void BrickStepper::setSPITFPBaudrateConfig(bool $enable_dynamic_baudrate, int $minimum_dynamic_baudrate)

The SPITF protocol can be used with a dynamic baudrate. If the dynamic baudrate is enabled, the Brick will try to adapt the baudrate for the communication between Bricks and Bricklets according to the amount of data that is transferred.

The baudrate will be increased exponentially if lots of data is send/received and decreased linearly if little data is send/received.

This lowers the baudrate in applications where little data is transferred (e.g. a weather station) and increases the robustness. If there is lots of data to transfer (e.g. Thermal Imaging Bricklet) it automatically increases the baudrate as needed.

In cases where some data has to transferred as fast as possible every few seconds (e.g. RS485 Bricklet with a high baudrate but small payload) you may want to turn the dynamic baudrate off to get the highest possible performance.

The maximum value of the baudrate can be set per port with the function setSPITFPBaudrate(). If the dynamic baudrate is disabled, the baudrate as set by setSPITFPBaudrate() will be used statically.

The minimum dynamic baudrate has a value range of 400000 to 2000000 baud.

By default dynamic baudrate is enabled and the minimum dynamic baudrate is 400000.

New in version 2.3.6 (Firmware).

array BrickStepper::getSPITFPBaudrateConfig()

Returns the baudrate config, see setSPITFPBaudrateConfig().

New in version 2.3.6 (Firmware).

The returned array has the keys enable_dynamic_baudrate and minimum_dynamic_baudrate.

int BrickStepper::getSendTimeoutCount(int $communication_method)

Returns the timeout count for the different communication methods.

The methods 0-2 are available for all Bricks, 3-7 only for Master Bricks.

This function is mostly used for debugging during development, in normal operation the counters should nearly always stay at 0.

The following constants are available for this function:

  • BrickStepper::COMMUNICATION_METHOD_NONE = 0
  • BrickStepper::COMMUNICATION_METHOD_USB = 1
  • BrickStepper::COMMUNICATION_METHOD_SPI_STACK = 2
  • BrickStepper::COMMUNICATION_METHOD_CHIBI = 3
  • BrickStepper::COMMUNICATION_METHOD_RS485 = 4
  • BrickStepper::COMMUNICATION_METHOD_WIFI = 5
  • BrickStepper::COMMUNICATION_METHOD_ETHERNET = 6
  • BrickStepper::COMMUNICATION_METHOD_WIFI_V2 = 7

New in version 2.3.4 (Firmware).

void BrickStepper::setSPITFPBaudrate(string $bricklet_port, int $baudrate)

Sets the baudrate for a specific Bricklet port ('a' - 'd'). The baudrate can be in the range 400000 to 2000000.

If you want to increase the throughput of Bricklets you can increase the baudrate. If you get a high error count because of high interference (see getSPITFPErrorCount()) you can decrease the baudrate.

If the dynamic baudrate feature is enabled, the baudrate set by this function corresponds to the maximum baudrate (see setSPITFPBaudrateConfig()).

Regulatory testing is done with the default baudrate. If CE compatibility or similar is necessary in you applications we recommend to not change the baudrate.

The default baudrate for all ports is 1400000.

New in version 2.3.3 (Firmware).

int BrickStepper::getSPITFPBaudrate(string $bricklet_port)

Returns the baudrate for a given Bricklet port, see setSPITFPBaudrate().

New in version 2.3.3 (Firmware).

array BrickStepper::getSPITFPErrorCount(string $bricklet_port)

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 Brick side. All Bricklets have a similar function that returns the errors on the Bricklet side.

New in version 2.3.3 (Firmware).

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

void BrickStepper::enableStatusLED()

Enables the status LED.

The status LED is the blue LED next to the USB connector. If enabled is is on and it flickers if data is transfered. If disabled it is always off.

The default state is enabled.

New in version 2.3.1 (Firmware).

void BrickStepper::disableStatusLED()

Disables the status LED.

The status LED is the blue LED next to the USB connector. If enabled is is on and it flickers if data is transfered. If disabled it is always off.

The default state is enabled.

New in version 2.3.1 (Firmware).

bool BrickStepper::isStatusLEDEnabled()

Returns true if the status LED is enabled, false otherwise.

New in version 2.3.1 (Firmware).

array BrickStepper::getProtocol1BrickletName(string $port)

Returns the firmware and protocol version and the name of the Bricklet for a given port.

This functions sole purpose is to allow automatic flashing of v1.x.y Bricklet plugins.

The returned array has the keys protocol_version, firmware_version and name.

int BrickStepper::getChipTemperature()

Returns the temperature in °C/10 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 an accuracy of +-15%. Practically it is only useful as an indicator for temperature changes.

void BrickStepper::reset()

Calling this function will reset the Brick. Calling this function on a Brick inside of a stack will reset the whole stack.

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

array BrickStepper::getIdentity()

Returns the UID, the UID where the Brick is connected to, the position, the hardware and firmware version as well as the device identifier.

The position can be '0'-'8' (stack position).

The device identifier numbers can be found here. There is also a constant for the device identifier of this Brick.

The returned array has the keys uid, connected_uid, position, hardware_version, firmware_version and device_identifier.

Callback Configuration Functions

void BrickStepper::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 BrickStepper::setMinimumVoltage(int $voltage)

Sets the minimum voltage in mV, below which the CALLBACK_UNDER_VOLTAGE callback is triggered. The minimum possible value that works with the Stepper Brick is 8V. You can use this function to detect the discharge of a battery that is used to drive the stepper motor. If you have a fixed power supply, you likely do not need this functionality.

The default value is 8V.

int BrickStepper::getMinimumVoltage()

Returns the minimum voltage as set by setMinimumVoltage().

void BrickStepper::setAllDataPeriod(int $period)

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

int BrickStepper::getAllDataPeriod()

Returns the period as set by setAllDataPeriod().

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";
}

$stepper->registerCallback(BrickStepper::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 BrickStepper::CALLBACK_UNDER_VOLTAGE
<?php   void callback(int $voltage [, mixed $user_data])   ?>

This callback is triggered when the input voltage drops below the value set by setMinimumVoltage(). The parameter is the current voltage given in mV.

int BrickStepper::CALLBACK_POSITION_REACHED
<?php   void callback(int $position [, mixed $user_data])   ?>

This callback is triggered when a position set by setSteps() or setTargetPosition() is reached.

Note

Since we can't get any feedback from the stepper motor, this only works if the acceleration (see setSpeedRamping()) is set smaller or equal to the maximum acceleration of the motor. Otherwise the motor will lag behind the control value and the callback will be triggered too early.

int BrickStepper::CALLBACK_ALL_DATA
<?php   void callback(int $current_velocity, int $current_position, int $remaining_steps, int $stack_voltage, int $external_voltage, int $current_consumption [, mixed $user_data])   ?>

This callback is triggered periodically with the period that is set by setAllDataPeriod(). The parameters are: the current velocity, the current position, the remaining steps, the stack voltage, the external voltage and the current consumption of the stepper motor.

int BrickStepper::CALLBACK_NEW_STATE
<?php   void callback(int $state_new, int $state_previous [, mixed $user_data])   ?>

This callback is triggered whenever the Stepper Brick enters a new state. It returns the new state as well as the previous state.

The following constants are available for this function:

  • BrickStepper::STATE_STOP = 1
  • BrickStepper::STATE_ACCELERATION = 2
  • BrickStepper::STATE_RUN = 3
  • BrickStepper::STATE_DEACCELERATION = 4
  • BrickStepper::STATE_DIRECTION_CHANGE_TO_FORWARD = 5
  • BrickStepper::STATE_DIRECTION_CHANGE_TO_BACKWARD = 6

Constants

int BrickStepper::DEVICE_IDENTIFIER

This constant is used to identify a Stepper Brick.

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 BrickStepper::DEVICE_DISPLAY_NAME

This constant represents the human readable name of a Stepper Brick.