MATLAB/Octave - Motion Detector Bricklet

This is the description of the MATLAB/Octave API bindings for the Motion Detector Bricklet. General information and technical specifications for the Motion Detector Bricklet 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).

Callback (MATLAB)

Download (matlab_example_callback.m)

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

    HOST = 'localhost';
    PORT = 4223;
    UID = 'XYZ'; % Change XYZ to the UID of your Motion Detector Bricklet

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

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

    % Register motion detected callback to function cb_motion_detected
    set(md, 'MotionDetectedCallback', @(h, e) cb_motion_detected(e));

    % Register detection cycle ended callback to function cb_detection_cycle_ended
    set(md, 'DetectionCycleEndedCallback', @(h, e) cb_detection_cycle_ended(e));

    input('Press key to exit\n', 's');
    ipcon.disconnect();
end

% Callback function for motion detected callback
function cb_motion_detected(e)
    fprintf('Motion Detected\n');
end

% Callback function for detection cycle ended callback
function cb_detection_cycle_ended(e)
    fprintf('Detection Cycle Ended (next detection possible in ~3 seconds)\n');
end

Callback (Octave)

Download (octave_example_callback.m)

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function octave_example_callback()
    more off;

    HOST = "localhost";
    PORT = 4223;
    UID = "XYZ"; % Change XYZ to the UID of your Motion Detector Bricklet

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

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

    % Register motion detected callback to function cb_motion_detected
    md.addMotionDetectedCallback(@cb_motion_detected);

    % Register detection cycle ended callback to function cb_detection_cycle_ended
    md.addDetectionCycleEndedCallback(@cb_detection_cycle_ended);

    input("Press key to exit\n", "s");
    ipcon.disconnect();
end

% Callback function for motion detected callback
function cb_motion_detected(e)
    fprintf("Motion Detected\n");
end

% Callback function for detection cycle ended callback
function cb_detection_cycle_ended(e)
    fprintf("Detection Cycle Ended (next detection possible in ~3 seconds)\n");
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 BrickletMotionDetector(String uid, IPConnection ipcon)

Creates an object with the unique device ID uid.

In MATLAB:

import com.tinkerforge.BrickletMotionDetector;

motionDetector = BrickletMotionDetector('YOUR_DEVICE_UID', ipcon);

In Octave:

motionDetector = java_new("com.tinkerforge.BrickletMotionDetector", "YOUR_DEVICE_UID", ipcon);

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

public short getMotionDetected()

Returns 1 if a motion was detected. How long this returns 1 after a motion was detected can be adjusted with one of the small potentiometers on the Motion Detector Bricklet, see here.

There is also a blue LED on the Bricklet that is on as long as the Bricklet is in the "motion detected" state.

The following constants are available for this function:

  • BrickletMotionDetector.MOTION_NOT_DETECTED = 0
  • BrickletMotionDetector.MOTION_DETECTED = 1

Advanced Functions

public void setStatusLEDConfig(short config)

Sets the status led configuration.

By default the status LED turns on if a motion is detected and off is no motion is detected.

You can also turn the LED permanently on/off.

The following constants are available for this function:

  • BrickletMotionDetector.STATUS_LED_CONFIG_OFF = 0
  • BrickletMotionDetector.STATUS_LED_CONFIG_ON = 1
  • BrickletMotionDetector.STATUS_LED_CONFIG_SHOW_STATUS = 2

New in version 2.0.1 (Plugin).

public short getStatusLEDConfig()

Returns the configuration as set by setStatusLEDConfig().

The following constants are available for this function:

  • BrickletMotionDetector.STATUS_LED_CONFIG_OFF = 0
  • BrickletMotionDetector.STATUS_LED_CONFIG_ON = 1
  • BrickletMotionDetector.STATUS_LED_CONFIG_SHOW_STATUS = 2

New in version 2.0.1 (Plugin).

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:

  • BrickletMotionDetector.FUNCTION_SET_STATUS_LED_CONFIG = 4
public void setResponseExpectedAll(boolean responseExpected)

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

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

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 BrickletMotionDetector.MotionDetectedCallback

This callback is called after a motion was detected.

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 addMotionDetectedCallback() function. An added callback function can be removed with the removeMotionDetectedCallback() function.

public callback BrickletMotionDetector.DetectionCycleEndedCallback

This callback is called when the detection cycle ended. When this callback is called, a new motion can be detected again after approximately 2 seconds.

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 addDetectionCycleEndedCallback() function. An added callback function can be removed with the removeDetectionCycleEndedCallback() function.

Constants

public static final int BrickletMotionDetector.DEVICE_IDENTIFIER

This constant is used to identify a Motion Detector Bricklet.

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 BrickletMotionDetector.DEVICE_DISPLAY_NAME

This constant represents the human readable name of a Motion Detector Bricklet.