MATLAB/Octave - Multi Touch Bricklet 2.0

This is the description of the MATLAB/Octave API bindings for the Multi Touch Bricklet 2.0. General information and technical specifications for the Multi Touch Bricklet 2.0 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).

Simple (MATLAB)

Download (matlab_example_simple.m)

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function matlab_example_simple()
    import com.tinkerforge.IPConnection;
    import com.tinkerforge.BrickletMultiTouchV2;

    HOST = 'localhost';
    PORT = 4223;
    UID = 'XYZ'; % Change XYZ to the UID of your Multi Touch Bricklet 2.0

    ipcon = IPConnection(); % Create IP connection
    mt = handle(BrickletMultiTouchV2(UID, ipcon), 'CallbackProperties'); % Create device object

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

    % Get current touch state
    state = mt.getTouchState();

    fprintf('Electrode 0: %i\n', state(1));
    fprintf('Electrode 1: %i\n', state(2));
    fprintf('Electrode 2: %i\n', state(3));
    fprintf('Electrode 3: %i\n', state(4));
    fprintf('Electrode 4: %i\n', state(5));
    fprintf('Electrode 5: %i\n', state(6));
    fprintf('Electrode 6: %i\n', state(7));
    fprintf('Electrode 7: %i\n', state(8));
    fprintf('Electrode 8: %i\n', state(9));
    fprintf('Electrode 9: %i\n', state(10));
    fprintf('Electrode 10: %i\n', state(11));
    fprintf('Electrode 11: %i\n', state(12));
    fprintf('Proximity: %i\n', state(13));

    input('Press key to exit\n', 's');
    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.BrickletMultiTouchV2;

    HOST = 'localhost';
    PORT = 4223;
    UID = 'XYZ'; % Change XYZ to the UID of your Multi Touch Bricklet 2.0

    ipcon = IPConnection(); % Create IP connection
    mt = handle(BrickletMultiTouchV2(UID, ipcon), 'CallbackProperties'); % Create device object

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

    % Register touch state callback to function cb_touch_state
    set(mt, 'TouchStateCallback', @(h, e) cb_touch_state(e));

    % Set period for touch state callback to 0.01s (10ms)
    mt.setTouchStateCallbackConfiguration(10, true);

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

% Callback function for touch state callback
function cb_touch_state(e)
    fprintf('Electrode 0: %i\n', e.state(1));
    fprintf('Electrode 1: %i\n', e.state(2));
    fprintf('Electrode 2: %i\n', e.state(3));
    fprintf('Electrode 3: %i\n', e.state(4));
    fprintf('Electrode 4: %i\n', e.state(5));
    fprintf('Electrode 5: %i\n', e.state(6));
    fprintf('Electrode 6: %i\n', e.state(7));
    fprintf('Electrode 7: %i\n', e.state(8));
    fprintf('Electrode 8: %i\n', e.state(9));
    fprintf('Electrode 9: %i\n', e.state(10));
    fprintf('Electrode 10: %i\n', e.state(11));
    fprintf('Electrode 11: %i\n', e.state(12));
    fprintf('Proximity: %i\n', e.state(13));
    fprintf('\n');
end

Simple (Octave)

Download (octave_example_simple.m)

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function octave_example_simple()
    more off;

    HOST = "localhost";
    PORT = 4223;
    UID = "XYZ"; % Change XYZ to the UID of your Multi Touch Bricklet 2.0

    ipcon = javaObject("com.tinkerforge.IPConnection"); % Create IP connection
    mt = javaObject("com.tinkerforge.BrickletMultiTouchV2", UID, ipcon); % Create device object

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

    % Get current touch state
    state = mt.getTouchState();

    fprintf("Electrode 0: %d\n", state(1));
    fprintf("Electrode 1: %d\n", state(2));
    fprintf("Electrode 2: %d\n", state(3));
    fprintf("Electrode 3: %d\n", state(4));
    fprintf("Electrode 4: %d\n", state(5));
    fprintf("Electrode 5: %d\n", state(6));
    fprintf("Electrode 6: %d\n", state(7));
    fprintf("Electrode 7: %d\n", state(8));
    fprintf("Electrode 8: %d\n", state(9));
    fprintf("Electrode 9: %d\n", state(10));
    fprintf("Electrode 10: %d\n", state(11));
    fprintf("Electrode 11: %d\n", state(12));
    fprintf("Proximity: %d\n", state(13));

    input("Press key to exit\n", "s");
    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 = "XYZ"; % Change XYZ to the UID of your Multi Touch Bricklet 2.0

    ipcon = javaObject("com.tinkerforge.IPConnection"); % Create IP connection
    mt = javaObject("com.tinkerforge.BrickletMultiTouchV2", UID, ipcon); % Create device object

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

    % Register touch state callback to function cb_touch_state
    mt.addTouchStateCallback(@cb_touch_state);

    % Set period for touch state callback to 0.01s (10ms)
    mt.setTouchStateCallbackConfiguration(10, true);

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

% Callback function for touch state callback
function cb_touch_state(e)
    fprintf("Electrode 0: %d\n", e.state(1));
    fprintf("Electrode 1: %d\n", e.state(2));
    fprintf("Electrode 2: %d\n", e.state(3));
    fprintf("Electrode 3: %d\n", e.state(4));
    fprintf("Electrode 4: %d\n", e.state(5));
    fprintf("Electrode 5: %d\n", e.state(6));
    fprintf("Electrode 6: %d\n", e.state(7));
    fprintf("Electrode 7: %d\n", e.state(8));
    fprintf("Electrode 8: %d\n", e.state(9));
    fprintf("Electrode 9: %d\n", e.state(10));
    fprintf("Electrode 10: %d\n", e.state(11));
    fprintf("Electrode 11: %d\n", e.state(12));
    fprintf("Proximity: %d\n", e.state(13));
    fprintf("\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 BrickletMultiTouchV2(String uid, IPConnection ipcon)

Creates an object with the unique device ID uid.

In MATLAB:

import com.tinkerforge.BrickletMultiTouchV2;

multiTouchV2 = BrickletMultiTouchV2('YOUR_DEVICE_UID', ipcon);

In Octave:

multiTouchV2 = java_new("com.tinkerforge.BrickletMultiTouchV2", "YOUR_DEVICE_UID", ipcon);

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

public boolean[] getTouchState()

Returns the current touch state. The state is given as a array of bools.

Element 0 to 11 represent the 12 electrodes and element 12 represents the proximity.

If an electrode is touched, the corresponding element is true. If a hand or similar is in proximity to the electrodes, element 12 is true.

The proximity is activated with a distance of 1-2cm. An electrode is already counted as touched if a finger is nearly touching the electrode. This means that you can put a piece of paper or foil or similar on top of a electrode to build a touch panel with a professional look.

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

public void recalibrate()

Recalibrates the electrodes. Call this function whenever you changed or moved you electrodes.

public void setElectrodeConfig(boolean[] enabledElectrodes)

Enables/disables electrodes with a bool array (see getTouchState()).

True enables the electrode, false disables the electrode. A disabled electrode will always return false as its state. If you don't need all electrodes you can disable the electrodes that are not needed.

It is recommended that you disable the proximity electrode (element 12) if the proximity feature is not needed. This will reduce the amount of traffic that is produced by the TouchStateCallback callback.

Disabling electrodes will also reduce power consumption.

Default: All electrodes enabled.

public boolean[] getElectrodeConfig()

Returns the electrode configuration, as set by setElectrodeConfig().

public void setElectrodeSensitivity(int sensitivity)

Sets the sensitivity of the electrodes. An electrode with a high sensitivity will register a touch earlier then an electrode with a low sensitivity.

If you build a big electrode you might need to decrease the sensitivity, since the area that can be charged will get bigger. If you want to be able to activate an electrode from further away you need to increase the sensitivity.

After a new sensitivity is set, you likely want to call recalibrate() to calibrate the electrodes with the newly defined sensitivity.

The valid sensitivity value range is 5-201.

The default sensitivity value is 181.

public int getElectrodeSensitivity()

Returns the current sensitivity, as set by setElectrodeSensitivity().

public void setTouchLEDConfig(int config)

Configures the touch LED to be either turned off, turned on, blink in heartbeat mode or show the touch state (electrode touched = LED on).

The default value is 3 (show touch state).

The following constants are available for this function:

  • BrickletMultiTouchV2.TOUCH_LED_CONFIG_OFF = 0
  • BrickletMultiTouchV2.TOUCH_LED_CONFIG_ON = 1
  • BrickletMultiTouchV2.TOUCH_LED_CONFIG_SHOW_HEARTBEAT = 2
  • BrickletMultiTouchV2.TOUCH_LED_CONFIG_SHOW_TOUCH = 3
public int getTouchLEDConfig()

Returns the LED configuration as set by setTouchLEDConfig()

The following constants are available for this function:

  • BrickletMultiTouchV2.TOUCH_LED_CONFIG_OFF = 0
  • BrickletMultiTouchV2.TOUCH_LED_CONFIG_ON = 1
  • BrickletMultiTouchV2.TOUCH_LED_CONFIG_SHOW_HEARTBEAT = 2
  • BrickletMultiTouchV2.TOUCH_LED_CONFIG_SHOW_TOUCH = 3

Advanced Functions

public int[] 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(int 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.

The following constants are available for this function:

  • BrickletMultiTouchV2.FUNCTION_SET_TOUCH_STATE_CALLBACK_CONFIGURATION = 2
  • BrickletMultiTouchV2.FUNCTION_RECALIBRATE = 5
  • BrickletMultiTouchV2.FUNCTION_SET_ELECTRODE_CONFIG = 6
  • BrickletMultiTouchV2.FUNCTION_SET_ELECTRODE_SENSITIVITY = 8
  • BrickletMultiTouchV2.FUNCTION_SET_TOUCH_LED_CONFIG = 10
  • BrickletMultiTouchV2.FUNCTION_SET_WRITE_FIRMWARE_POINTER = 237
  • BrickletMultiTouchV2.FUNCTION_SET_STATUS_LED_CONFIG = 239
  • BrickletMultiTouchV2.FUNCTION_RESET = 243
  • BrickletMultiTouchV2.FUNCTION_WRITE_UID = 248
public void setResponseExpected(int 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 constants are available for this function:

  • BrickletMultiTouchV2.FUNCTION_SET_TOUCH_STATE_CALLBACK_CONFIGURATION = 2
  • BrickletMultiTouchV2.FUNCTION_RECALIBRATE = 5
  • BrickletMultiTouchV2.FUNCTION_SET_ELECTRODE_CONFIG = 6
  • BrickletMultiTouchV2.FUNCTION_SET_ELECTRODE_SENSITIVITY = 8
  • BrickletMultiTouchV2.FUNCTION_SET_TOUCH_LED_CONFIG = 10
  • BrickletMultiTouchV2.FUNCTION_SET_WRITE_FIRMWARE_POINTER = 237
  • BrickletMultiTouchV2.FUNCTION_SET_STATUS_LED_CONFIG = 239
  • BrickletMultiTouchV2.FUNCTION_RESET = 243
  • BrickletMultiTouchV2.FUNCTION_WRITE_UID = 248
public void setResponseExpectedAll(boolean responseExpected)

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

public BrickletMultiTouchV2.SPITFPErrorCount 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 object has the public member variables long errorCountAckChecksum, long errorCountMessageChecksum, long errorCountFrame and long errorCountOverflow.

public int 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:

  • BrickletMultiTouchV2.BOOTLOADER_MODE_BOOTLOADER = 0
  • BrickletMultiTouchV2.BOOTLOADER_MODE_FIRMWARE = 1
  • BrickletMultiTouchV2.BOOTLOADER_MODE_BOOTLOADER_WAIT_FOR_REBOOT = 2
  • BrickletMultiTouchV2.BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_REBOOT = 3
  • BrickletMultiTouchV2.BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_ERASE_AND_REBOOT = 4
  • BrickletMultiTouchV2.BOOTLOADER_STATUS_OK = 0
  • BrickletMultiTouchV2.BOOTLOADER_STATUS_INVALID_MODE = 1
  • BrickletMultiTouchV2.BOOTLOADER_STATUS_NO_CHANGE = 2
  • BrickletMultiTouchV2.BOOTLOADER_STATUS_ENTRY_FUNCTION_NOT_PRESENT = 3
  • BrickletMultiTouchV2.BOOTLOADER_STATUS_DEVICE_IDENTIFIER_INCORRECT = 4
  • BrickletMultiTouchV2.BOOTLOADER_STATUS_CRC_MISMATCH = 5
public int getBootloaderMode()

Returns the current bootloader mode, see setBootloaderMode().

The following constants are available for this function:

  • BrickletMultiTouchV2.BOOTLOADER_MODE_BOOTLOADER = 0
  • BrickletMultiTouchV2.BOOTLOADER_MODE_FIRMWARE = 1
  • BrickletMultiTouchV2.BOOTLOADER_MODE_BOOTLOADER_WAIT_FOR_REBOOT = 2
  • BrickletMultiTouchV2.BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_REBOOT = 3
  • BrickletMultiTouchV2.BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_ERASE_AND_REBOOT = 4
public void setWriteFirmwarePointer(long 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.

public int writeFirmware(int[] 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.

public void 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:

  • BrickletMultiTouchV2.STATUS_LED_CONFIG_OFF = 0
  • BrickletMultiTouchV2.STATUS_LED_CONFIG_ON = 1
  • BrickletMultiTouchV2.STATUS_LED_CONFIG_SHOW_HEARTBEAT = 2
  • BrickletMultiTouchV2.STATUS_LED_CONFIG_SHOW_STATUS = 3
public int getStatusLEDConfig()

Returns the configuration as set by setStatusLEDConfig()

The following constants are available for this function:

  • BrickletMultiTouchV2.STATUS_LED_CONFIG_OFF = 0
  • BrickletMultiTouchV2.STATUS_LED_CONFIG_ON = 1
  • BrickletMultiTouchV2.STATUS_LED_CONFIG_SHOW_HEARTBEAT = 2
  • BrickletMultiTouchV2.STATUS_LED_CONFIG_SHOW_STATUS = 3
public int 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.

public void 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!

public void writeUID(long 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.

public long readUID()

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

public BrickletMultiTouchV2.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, int[] hardwareVersion, int[] firmwareVersion and int deviceIdentifier.

Callback Configuration Functions

public void setTouchStateCallbackConfiguration(long period, boolean valueHasToChange)

The period in ms is the period with which the TouchStateCallback 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).

public BrickletMultiTouchV2.TouchStateCallbackConfiguration getTouchStateCallbackConfiguration()

Returns the callback configuration as set by setTouchStateCallbackConfiguration().

The returned object has the public member variables long period and boolean valueHasToChange.

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 TouchStateCallback
Parameters:state -- boolean[]

Returns the current touch state, see getTouchState() for information about the state.

This callback is triggered every time the touch state changes with a given period (see setTouchStateCallbackConfiguration())

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 addTouchStateCallback() function. An added callback function can be removed with the removeTouchStateCallback() function.

Constants

public static final int DEVICE_IDENTIFIER

This constant is used to identify a Multi Touch Bricklet 2.0.

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

public static final String DEVICE_DISPLAY_NAME

This constant represents the human readable name of a Multi Touch Bricklet 2.0.