MATLAB/Octave - DC Brick

This is the description of the MATLAB/Octave API bindings for the DC Brick. General information and technical specifications for the DC Brick are summarized in its hardware description.

An installation guide for the MATLAB/Octave API bindings is part of their general description.

Examples

The example code below is Public Domain (CC0 1.0).

Configuration (MATLAB)

Download (matlab_example_configuration.m)

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function matlab_example_configuration()
    import com.tinkerforge.IPConnection;
    import com.tinkerforge.BrickDC;

    HOST = 'localhost';
    PORT = 4223;
    UID = 'XXYYZZ'; % Change XXYYZZ to the UID of your DC Brick

    ipcon = IPConnection(); % Create IP connection
    dc = handle(BrickDC(UID, ipcon), 'CallbackProperties'); % Create device object

    ipcon.connect(HOST, PORT); % Connect to brickd
    % Don't use device before ipcon is connected

    dc.setDriveMode(BrickDC.DRIVE_MODE_DRIVE_COAST);
    dc.setPWMFrequency(10000); % Use PWM frequency of 10kHz
    dc.setAcceleration(5000); % Slow acceleration
    dc.setVelocity(32767); % Full speed forward
    dc.enable(); % Enable motor power

    input('Press key to exit\n', 's');
    dc.disable(); % Disable motor power
    ipcon.disconnect();
end

Callback (MATLAB)

Download (matlab_example_callback.m)

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function matlab_example_callback()
    import com.tinkerforge.IPConnection;
    import com.tinkerforge.BrickDC;

    HOST = 'localhost';
    PORT = 4223;
    UID = 'XXYYZZ'; % Change XXYYZZ to the UID of your DC Brick

    ipcon = IPConnection(); % Create IP connection
    dc = handle(BrickDC(UID, ipcon), 'CallbackProperties'); % Create device object

    ipcon.connect(HOST, PORT); % Connect to brickd
    % Don't use device before ipcon is connected

    % The acceleration has to be smaller or equal to the maximum
    % acceleration of the DC motor, otherwise the velocity reached
    % callback will be called too early
    dc.setAcceleration(5000); % Slow acceleration
    dc.setVelocity(32767); % Full speed forward

    % Register velocity reached callback to function cb_velocity_reached
    set(dc, 'VelocityReachedCallback', @(h, e) cb_velocity_reached(e));

    % Enable motor power
    dc.enable();

    input('Press key to exit\n', 's');
    dc.disable(); % Disable motor power
    ipcon.disconnect();
end

% Use velocity reached callback to swing back and forth
% between full speed forward and full speed backward
function cb_velocity_reached(e)
    dc = e.getSource();

    if e.velocity == 32767
        fprintf('Velocity: Full speed forward, now turning backward\n');
        dc.setVelocity(-32767);
    elseif e.velocity == -32767
        fprintf('Velocity: Full speed backward, now turning forward\n');
        dc.setVelocity(32767);
    else
        fprintf('Error\n'); % Can only happen if another program sets velocity
    end
end

Configuration (Octave)

Download (octave_example_configuration.m)

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function octave_example_configuration()
    more off;

    HOST = "localhost";
    PORT = 4223;
    UID = "XXYYZZ"; % Change XXYYZZ to the UID of your DC Brick

    ipcon = javaObject("com.tinkerforge.IPConnection"); % Create IP connection
    dc = javaObject("com.tinkerforge.BrickDC", UID, ipcon); % Create device object

    ipcon.connect(HOST, PORT); % Connect to brickd
    % Don't use device before ipcon is connected

    dc.setDriveMode(dc.DRIVE_MODE_DRIVE_COAST);
    dc.setPWMFrequency(10000); % Use PWM frequency of 10kHz
    dc.setAcceleration(5000); % Slow acceleration
    dc.setVelocity(32767); % Full speed forward
    dc.enable(); % Enable motor power

    input("Press key to exit\n", "s");
    dc.disable(); % Disable motor power
    ipcon.disconnect();
end

Callback (Octave)

Download (octave_example_callback.m)

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function octave_example_callback()
    more off;

    HOST = "localhost";
    PORT = 4223;
    UID = "XXYYZZ"; % Change XXYYZZ to the UID of your DC Brick

    ipcon = javaObject("com.tinkerforge.IPConnection"); % Create IP connection
    dc = javaObject("com.tinkerforge.BrickDC", UID, ipcon); % Create device object

    ipcon.connect(HOST, PORT); % Connect to brickd
    % Don't use device before ipcon is connected

    % The acceleration has to be smaller or equal to the maximum
    % acceleration of the DC motor, otherwise the velocity reached
    % callback will be called too early
    dc.setAcceleration(5000); % Slow acceleration
    dc.setVelocity(32767); % Full speed forward

    % Register velocity reached callback to function cb_velocity_reached
    dc.addVelocityReachedCallback(@cb_velocity_reached);

    % Enable motor power
    dc.enable();

    input("Press key to exit\n", "s");
    dc.disable(); % Disable motor power
    ipcon.disconnect();
end

% Use velocity reached callback to swing back and forth
% between full speed forward and full speed backward
function cb_velocity_reached(e)
    dc = e.getSource();
    velocity = short2int(e.velocity);

    if velocity == 32767
        fprintf("Velocity: Full speed forward, now turning backward\n");
        dc.setVelocity(-32767);
    elseif velocity == -32767
        fprintf("Velocity: Full speed backward, now turning forward\n");
        dc.setVelocity(32767);
    else
        fprintf("Error\n"); % Can only happen if another program sets velocity
    end
end

function int = java2int(value)
    if compare_versions(version(), "3.8", "<=")
        int = value.intValue();
    else
        int = value;
    end
end

API

Generally, every method of the MATLAB bindings that returns a value can throw a TimeoutException. This exception gets thrown if the device did not respond. If a cable based connection is used, it is unlikely that this exception gets thrown (assuming nobody unplugs the device). However, if a wireless connection is used, timeouts will occur if the distance to the device gets too big.

Beside the TimeoutException there is also a NotConnectedException that is thrown if a method needs to communicate with the device while the IP Connection is not connected.

Since the MATLAB bindings are based on Java and Java does not support multiple return values and return by reference is not possible for primitive types, we use small classes that only consist of member variables. The member variables of the returned objects are described in the corresponding method descriptions.

The package for all Brick/Bricklet bindings and the IP Connection is com.tinkerforge.*

All methods listed below are thread-safe.

Basic Functions

public class BrickDC(String uid, IPConnection ipcon)

Creates an object with the unique device ID uid.

In MATLAB:

import com.tinkerforge.BrickDC;

dc = BrickDC('YOUR_DEVICE_UID', ipcon);

In Octave:

dc = java_new("com.tinkerforge.BrickDC", "YOUR_DEVICE_UID", ipcon);

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

public void setVelocity(short velocity)

Sets the velocity of the motor. Whereas -32767 is full speed backward, 0 is stop and 32767 is full speed forward. Depending on the acceleration (see setAcceleration()), the motor is not immediately brought to the velocity but smoothly accelerated.

The velocity describes the duty cycle of the PWM with which the motor is controlled, e.g. a velocity of 3277 sets a PWM with a 10% duty cycle. You can not only control the duty cycle of the PWM but also the frequency, see setPWMFrequency().

The default velocity is 0.

public short getVelocity()

Returns the velocity as set by setVelocity().

public short getCurrentVelocity()

Returns the current velocity of the motor. This value is different from getVelocity() whenever the motor is currently accelerating to a goal set by setVelocity().

public void setAcceleration(int acceleration)

Sets the acceleration of the motor. It is given in velocity/s. An acceleration of 10000 means, that every second the velocity is increased by 10000 (or about 30% duty cycle).

For example: If the current velocity is 0 and you want to accelerate to a velocity of 16000 (about 50% duty cycle) in 10 seconds, you should set an acceleration of 1600.

If acceleration is set to 0, there is no speed ramping, i.e. a new velocity is immediately given to the motor.

The default acceleration is 10000.

public int getAcceleration()

Returns the acceleration as set by setAcceleration().

public void 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 setVelocity() with 0 if you just want to stop the motor.

public void enable()

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

public void disable()

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

public boolean isEnabled()

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

Advanced Functions

public void setPWMFrequency(int frequency)

Sets the frequency (in Hz) of the PWM with which the motor is driven. The possible range of the frequency is 1-20000Hz. Often a high frequency is less noisy and the motor runs smoother. However, with a low frequency there are less switches and therefore fewer switching losses. Also with most motors lower frequencies enable higher torque.

If you have no idea what all this means, just ignore this function and use the default frequency, it will very likely work fine.

The default frequency is 15 kHz.

public int getPWMFrequency()

Returns the PWM frequency (in Hz) as set by setPWMFrequency().

public int 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.

public int getExternalInputVoltage()

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

public int getCurrentConsumption()

Returns the current consumption of the motor in mA.

public void setDriveMode(short mode)

Sets the drive mode. Possible modes are:

  • 0 = Drive/Brake
  • 1 = Drive/Coast

These modes are different kinds of motor controls.

In Drive/Brake mode, the motor is always either driving or braking. There is no freewheeling. Advantages are: A more linear correlation between PWM and velocity, more exact accelerations and the possibility to drive with slower velocities.

In Drive/Coast mode, the motor is always either driving or freewheeling. Advantages are: Less current consumption and less demands on the motor and driver chip.

The default value is 0 = Drive/Brake.

The following constants are available for this function:

  • BrickDC.DRIVE_MODE_DRIVE_BRAKE = 0
  • BrickDC.DRIVE_MODE_DRIVE_COAST = 1
public short getDriveMode()

Returns the drive mode, as set by setDriveMode().

The following constants are available for this function:

  • BrickDC.DRIVE_MODE_DRIVE_BRAKE = 0
  • BrickDC.DRIVE_MODE_DRIVE_COAST = 1
public short[] 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.

public boolean getResponseExpected(short functionId)

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.

public void setResponseExpected(short functionId, boolean responseExpected)

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:

  • BrickDC.FUNCTION_SET_VELOCITY = 1
  • BrickDC.FUNCTION_SET_ACCELERATION = 4
  • BrickDC.FUNCTION_SET_PWM_FREQUENCY = 6
  • BrickDC.FUNCTION_FULL_BRAKE = 8
  • BrickDC.FUNCTION_ENABLE = 12
  • BrickDC.FUNCTION_DISABLE = 13
  • BrickDC.FUNCTION_SET_MINIMUM_VOLTAGE = 15
  • BrickDC.FUNCTION_SET_DRIVE_MODE = 17
  • BrickDC.FUNCTION_SET_CURRENT_VELOCITY_PERIOD = 19
  • BrickDC.FUNCTION_SET_SPITFP_BAUDRATE_CONFIG = 231
  • BrickDC.FUNCTION_SET_SPITFP_BAUDRATE = 234
  • BrickDC.FUNCTION_ENABLE_STATUS_LED = 238
  • BrickDC.FUNCTION_DISABLE_STATUS_LED = 239
  • BrickDC.FUNCTION_RESET = 243
public void setResponseExpectedAll(boolean responseExpected)

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

public void setSPITFPBaudrateConfig(boolean enableDynamicBaudrate, long minimumDynamicBaudrate)

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 2.3.5 (Firmware).

public BrickDC.SPITFPBaudrateConfig getSPITFPBaudrateConfig()

Returns the baudrate config, see setSPITFPBaudrateConfig().

New in version 2.3.5 (Firmware).

The returned object has the public member variables boolean enableDynamicBaudrate and long minimumDynamicBaudrate.

public long getSendTimeoutCount(short communicationMethod)

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:

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

New in version 2.3.3 (Firmware).

public void setSPITFPBaudrate(char brickletPort, long 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).

public long getSPITFPBaudrate(char brickletPort)

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

New in version 2.3.3 (Firmware).

public BrickDC.SPITFPErrorCount getSPITFPErrorCount(char brickletPort)

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 object has the public member variables long errorCountACKChecksum, long errorCountMessageChecksum, long errorCountFrame and long errorCountOverflow.

public void 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).

public void 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).

public boolean isStatusLEDEnabled()

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

New in version 2.3.1 (Firmware).

public BrickDC.Protocol1BrickletName getProtocol1BrickletName(char 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 object has the public member variables short protocolVersion, short[] firmwareVersion and String name.

public short 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.

public void 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!

public BrickDC.Identity 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 object has the public member variables String uid, String connectedUid, char position, short[] hardwareVersion, short[] firmwareVersion and int deviceIdentifier.

Callback Configuration Functions

public void setMinimumVoltage(int voltage)

Sets the minimum voltage in mV, below which the UnderVoltageCallback callback is triggered. The minimum possible value that works with the DC Brick is 6V. You can use this function to detect the discharge of a battery that is used to drive the motor. If you have a fixed power supply, you likely do not need this functionality.

The default value is 6V.

public int getMinimumVoltage()

Returns the minimum voltage as set by setMinimumVoltage()

public void setCurrentVelocityPeriod(int period)

Sets a period in ms with which the CurrentVelocityCallback callback is triggered. A period of 0 turns the callback off.

The default value is 0.

public int getCurrentVelocityPeriod()

Returns the period as set by setCurrentVelocityPeriod().

Callbacks

Callbacks can be registered to receive time critical or recurring data from the device. The registration is done with "set" function of MATLAB. The parameters consist of the IP Connection object, the callback name and the callback function. For example, it looks like this in MATLAB:

function my_callback(e)
    fprintf('Parameter: %s\n', e.param);
end

set(device, 'ExampleCallback', @(h, e) my_callback(e));

Due to a difference in the Octave Java support the "set" function cannot be used in Octave. The registration is done with "add*Callback" functions of the device object. It looks like this in Octave:

function my_callback(e)
    fprintf("Parameter: %s\n", e.param);
end

device.addExampleCallback(@my_callback);

It is possible to add several callbacks and to remove them with the corresponding "remove*Callback" function.

The parameters of the callback are passed to the callback function as fields of the structure e, which is derived from the java.util.EventObject class. The available callback names with corresponding structure fields 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.

public callback BrickDC.UnderVoltageCallback
Parameters:voltage -- int

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

In MATLAB the set() function can be used to register a callback function to this callback.

In Octave a callback function can be added to this callback using the addUnderVoltageCallback() function. An added callback function can be removed with the removeUnderVoltageCallback() function.

public callback BrickDC.EmergencyShutdownCallback

This callback is triggered if either the current consumption is too high (above 5A) or the temperature of the driver chip is too high (above 175°C). These two possibilities are essentially the same, since the temperature will reach this threshold immediately if the motor consumes too much current. In case of a voltage below 3.3V (external or stack) this callback is triggered as well.

If this callback is triggered, the driver chip gets disabled at the same time. That means, enable() has to be called to drive the motor again.

Note

This callback only works in Drive/Brake mode (see setDriveMode()). In Drive/Coast mode it is unfortunately impossible to reliably read the overcurrent/overtemperature signal from the driver chip.

In MATLAB the set() function can be used to register a callback function to this callback.

In Octave a callback function can be added to this callback using the addEmergencyShutdownCallback() function. An added callback function can be removed with the removeEmergencyShutdownCallback() function.

public callback BrickDC.VelocityReachedCallback
Parameters:velocity -- short

This callback is triggered whenever a set velocity is reached. For example: If a velocity of 0 is present, acceleration is set to 5000 and velocity to 10000, the VelocityReachedCallback callback will be triggered after about 2 seconds, when the set velocity is actually reached.

Note

Since we can't get any feedback from the DC motor, this only works if the acceleration (see setAcceleration()) 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.

In MATLAB the set() function can be used to register a callback function to this callback.

In Octave a callback function can be added to this callback using the addVelocityReachedCallback() function. An added callback function can be removed with the removeVelocityReachedCallback() function.

public callback BrickDC.CurrentVelocityCallback
Parameters:velocity -- short

This callback is triggered with the period that is set by setCurrentVelocityPeriod(). The parameter is the current velocity used by the motor.

The CurrentVelocityCallback callback is only triggered after the set period if there is a change in the velocity.

In MATLAB the set() function can be used to register a callback function to this callback.

In Octave a callback function can be added to this callback using the addCurrentVelocityCallback() function. An added callback function can be removed with the removeCurrentVelocityCallback() function.

Constants

public static final int BrickDC.DEVICE_IDENTIFIER

This constant is used to identify a DC Brick.

The getIdentity() function and the EnumerateCallback callback of the IP Connection have a deviceIdentifier parameter to specify the Brick's or Bricklet's type.

public static final String BrickDC.DEVICE_DISPLAY_NAME

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