Software / API Bindings / MATLAB/Octave / API Reference and Examples / Bricklets / Joystick Bricklet 2.0

MATLAB/Octave - Joystick Bricklet 2.0¶

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

function matlab_example_simple()
    import com.tinkerforge.IPConnection;
    import com.tinkerforge.BrickletJoystickV2;

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

    ipcon = IPConnection(); % Create IP connection
    j = handle(BrickletJoystickV2(UID, ipcon), 'CallbackProperties'); % Create device object

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

    % Get current position
    position = j.getPosition();

    fprintf('Position [X]: %i\n', position.x);
    fprintf('Position [Y]: %i\n', position.y);

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

Callback (MATLAB)¶

Download (matlab_example_callback.m)

function matlab_example_callback()
    import com.tinkerforge.IPConnection;
    import com.tinkerforge.BrickletJoystickV2;

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

    ipcon = IPConnection(); % Create IP connection
    j = handle(BrickletJoystickV2(UID, ipcon), 'CallbackProperties'); % Create device object

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

    % Register pressed callback to function cb_pressed
    set(j, 'PressedCallback', @(h, e) cb_pressed(e));

    % Set period for pressed callback to 0.01s (10ms)
    j.setPressedCallbackConfiguration(10, true);

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

% Callback function for pressed callback
function cb_pressed(e)
    fprintf('Pressed: %i\n', e.pressed);
end

Simple (Octave)¶

Download (octave_example_simple.m)

function octave_example_simple()
    more off;

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

    ipcon = javaObject("com.tinkerforge.IPConnection"); % Create IP connection
    j = javaObject("com.tinkerforge.BrickletJoystickV2", UID, ipcon); % Create device object

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

    % Get current position
    position = j.getPosition();

    fprintf("Position [X]: %d\n", position.x);
    fprintf("Position [Y]: %d\n", position.y);

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

Callback (Octave)¶

Download (octave_example_callback.m)

function octave_example_callback()
    more off;

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

    ipcon = javaObject("com.tinkerforge.IPConnection"); % Create IP connection
    j = javaObject("com.tinkerforge.BrickletJoystickV2", UID, ipcon); % Create device object

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

    % Register pressed callback to function cb_pressed
    j.addPressedCallback(@cb_pressed);

    % Set period for pressed callback to 0.01s (10ms)
    j.setPressedCallbackConfiguration(10, true);

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

% Callback function for pressed callback
function cb_pressed(e)
    fprintf("Pressed: %d\n", e.pressed);
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¶

class BrickletJoystickV2(String uid, IPConnection ipcon)¶

Parameters:	uid – Type: String ipcon – Type: IPConnection
Returns:	joystickV2 – Type: BrickletJoystickV2

Creates an object with the unique device ID uid.

In MATLAB:

import com.tinkerforge.BrickletJoystickV2;

joystickV2 = BrickletJoystickV2('YOUR_DEVICE_UID', ipcon);

In Octave:

joystickV2 = java_new("com.tinkerforge.BrickletJoystickV2", "YOUR_DEVICE_UID", ipcon);

This object can then be used after the IP Connection is connected.

BrickletJoystickV2.Position BrickletJoystickV2.getPosition()¶

Return Object:	x – Type: int, Range: [-100 to 100] y – Type: int, Range: [-100 to 100]

Returns the position of the joystick. The middle position of the joystick is x=0, y=0. The returned values are averaged and calibrated (see calibrate()).

If you want to get the position periodically, it is recommended to use the PositionCallback callback and set the period with setPositionCallbackConfiguration().

boolean BrickletJoystickV2.isPressed()¶

Returns:	pressed – Type: boolean

Returns true if the button is pressed and false otherwise.

If you want to get the press-state periodically, it is recommended to use the PressedCallback callback and set the period with setPressedCallbackConfiguration().

Advanced Functions¶

void BrickletJoystickV2.calibrate()¶

Calibrates the middle position of the joystick. If your Joystick Bricklet 2.0 does not return x=0 and y=0 in the middle position, call this function while the joystick is standing still in the middle position.

The resulting calibration will be saved in non-volatile memory, thus you only have to calibrate it once.

BrickletJoystickV2.SPITFPErrorCount BrickletJoystickV2.getSPITFPErrorCount()¶

Return Object:	errorCountAckChecksum – Type: long, Range: [0 to 2³² - 1] errorCountMessageChecksum – Type: long, Range: [0 to 2³² - 1] errorCountFrame – Type: long, Range: [0 to 2³² - 1] errorCountOverflow – Type: long, Range: [0 to 2³² - 1]

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.

void BrickletJoystickV2.setStatusLEDConfig(int config)¶

Parameters:	config – Type: int, Range: See constants, Default: 3

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:

For config:

BrickletJoystickV2.STATUS_LED_CONFIG_OFF = 0
BrickletJoystickV2.STATUS_LED_CONFIG_ON = 1
BrickletJoystickV2.STATUS_LED_CONFIG_SHOW_HEARTBEAT = 2
BrickletJoystickV2.STATUS_LED_CONFIG_SHOW_STATUS = 3

int BrickletJoystickV2.getStatusLEDConfig()¶

Returns:	config – Type: int, Range: See constants, Default: 3

Returns the configuration as set by setStatusLEDConfig()

The following constants are available for this function:

For config:

BrickletJoystickV2.STATUS_LED_CONFIG_OFF = 0
BrickletJoystickV2.STATUS_LED_CONFIG_ON = 1
BrickletJoystickV2.STATUS_LED_CONFIG_SHOW_HEARTBEAT = 2
BrickletJoystickV2.STATUS_LED_CONFIG_SHOW_STATUS = 3

int BrickletJoystickV2.getChipTemperature()¶

Returns:	temperature – Type: int, Unit: 1 °C, Range: [-2¹⁵ to 2¹⁵ - 1]

Returns the temperature 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 BrickletJoystickV2.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!

BrickletJoystickV2.Identity BrickletJoystickV2.getIdentity()¶

Return Object:

Return Object:	uid – Type: String, Length: up to 8 connectedUid – Type: String, Length: up to 8 position – Type: char, Range: ['a' to 'h', 'z'] hardwareVersion – Type: short[], Length: 3 1: major – Type: short, Range: [0 to 255] 2: minor – Type: short, Range: [0 to 255] 3: revision – Type: short, Range: [0 to 255] firmwareVersion – Type: short[], Length: 3 1: major – Type: short, Range: [0 to 255] 2: minor – Type: short, Range: [0 to 255] 3: revision – Type: short, Range: [0 to 255] deviceIdentifier – Type: int, Range: [0 to 2¹⁶ - 1]

uid – Type: String, Length: up to 8
connectedUid – Type: String, Length: up to 8
position – Type: char, Range: ['a' to 'h', 'z']
hardwareVersion – Type: short[], Length: 3

1: major – Type: short, Range: [0 to 255]
2: minor – Type: short, Range: [0 to 255]
3: revision – Type: short, Range: [0 to 255]

firmwareVersion – Type: short[], Length: 3

1: major – Type: short, Range: [0 to 255]
2: minor – Type: short, Range: [0 to 255]
3: revision – Type: short, Range: [0 to 255]

deviceIdentifier – Type: int, Range: [0 to 2¹⁶ - 1]

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', 'd', 'e', 'f', 'g' or 'h' (Bricklet Port). A Bricklet connected to an Isolator Bricklet is always at position 'z'.

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

Callback Configuration Functions¶

void BrickletJoystickV2.setPositionCallbackConfiguration(long period, boolean valueHasToChange)¶

Parameters:	period – Type: long, Unit: 1 ms, Range: [0 to 2³² - 1], Default: 0 valueHasToChange – Type: boolean, Default: false

The period is the period with which the PositionCallback 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 at least one of the values has changed. If the values 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.

BrickletJoystickV2.PositionCallbackConfiguration BrickletJoystickV2.getPositionCallbackConfiguration()¶

Return Object:	period – Type: long, Unit: 1 ms, Range: [0 to 2³² - 1], Default: 0 valueHasToChange – Type: boolean, Default: false

Returns the callback configuration as set by setPositionCallbackConfiguration().

void BrickletJoystickV2.setPressedCallbackConfiguration(long period, boolean valueHasToChange)¶

Parameters:	period – Type: long, Unit: 1 ms, Range: [0 to 2³² - 1], Default: 0 valueHasToChange – Type: boolean, Default: false

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

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

BrickletJoystickV2.PressedCallbackConfiguration BrickletJoystickV2.getPressedCallbackConfiguration()¶

Return Object:	period – Type: long, Unit: 1 ms, Range: [0 to 2³² - 1], Default: 0 valueHasToChange – Type: boolean, Default: false

Returns the callback configuration as set by setPressedCallbackConfiguration().

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.

callback BrickletJoystickV2.PositionCallback¶

Event Object:	x – Type: int, Range: [-100 to 100] y – Type: int, Range: [-100 to 100]

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

The parameters are the same as with getPosition().

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 addPositionCallback() function. An added callback function can be removed with the removePositionCallback() function.

callback BrickletJoystickV2.PressedCallback¶

Event Object:	pressed – Type: boolean

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

The parameters are the same as with isPressed().

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 addPressedCallback() function. An added callback function can be removed with the removePressedCallback() function.

Virtual Functions¶

Virtual functions don't communicate with the device itself, but operate only on the API bindings device object. They can be called without the corresponding IP Connection object being connected.

short[] BrickletJoystickV2.getAPIVersion()¶

Return Object:	apiVersion – Type: short[], Length: 3 1: major – Type: short, Range: [0 to 255] 2: minor – Type: short, Range: [0 to 255] 3: revision – Type: short, Range: [0 to 255]

Returns the version of the API definition 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.

boolean BrickletJoystickV2.getResponseExpected(byte functionId)¶

Parameters:	functionId – Type: byte, Range: See constants
Returns:	responseExpected – Type: boolean

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 sent and errors are silently ignored, because they cannot be detected.

The following constants are available for this function:

For functionId:

BrickletJoystickV2.FUNCTION_CALIBRATE = 3
BrickletJoystickV2.FUNCTION_SET_POSITION_CALLBACK_CONFIGURATION = 4
BrickletJoystickV2.FUNCTION_SET_PRESSED_CALLBACK_CONFIGURATION = 7
BrickletJoystickV2.FUNCTION_SET_WRITE_FIRMWARE_POINTER = 237
BrickletJoystickV2.FUNCTION_SET_STATUS_LED_CONFIG = 239
BrickletJoystickV2.FUNCTION_RESET = 243
BrickletJoystickV2.FUNCTION_WRITE_UID = 248

void BrickletJoystickV2.setResponseExpected(byte functionId, boolean responseExpected)¶

Parameters:	functionId – Type: byte, Range: See constants responseExpected – Type: boolean

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.

The following constants are available for this function:

For functionId:

BrickletJoystickV2.FUNCTION_CALIBRATE = 3
BrickletJoystickV2.FUNCTION_SET_POSITION_CALLBACK_CONFIGURATION = 4
BrickletJoystickV2.FUNCTION_SET_PRESSED_CALLBACK_CONFIGURATION = 7
BrickletJoystickV2.FUNCTION_SET_WRITE_FIRMWARE_POINTER = 237
BrickletJoystickV2.FUNCTION_SET_STATUS_LED_CONFIG = 239
BrickletJoystickV2.FUNCTION_RESET = 243
BrickletJoystickV2.FUNCTION_WRITE_UID = 248

void BrickletJoystickV2.setResponseExpectedAll(boolean responseExpected)¶

Parameters:	responseExpected – Type: boolean

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

Internal Functions¶

Internal functions are used for maintenance tasks such as flashing a new firmware of changing the UID of a Bricklet. These task should be performed using Brick Viewer instead of using the internal functions directly.

int BrickletJoystickV2.setBootloaderMode(int mode)¶

Parameters:	mode – Type: int, Range: See constants
Returns:	status – Type: int, Range: See constants

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:

For mode:

BrickletJoystickV2.BOOTLOADER_MODE_BOOTLOADER = 0
BrickletJoystickV2.BOOTLOADER_MODE_FIRMWARE = 1
BrickletJoystickV2.BOOTLOADER_MODE_BOOTLOADER_WAIT_FOR_REBOOT = 2
BrickletJoystickV2.BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_REBOOT = 3
BrickletJoystickV2.BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_ERASE_AND_REBOOT = 4

For status:

BrickletJoystickV2.BOOTLOADER_STATUS_OK = 0
BrickletJoystickV2.BOOTLOADER_STATUS_INVALID_MODE = 1
BrickletJoystickV2.BOOTLOADER_STATUS_NO_CHANGE = 2
BrickletJoystickV2.BOOTLOADER_STATUS_ENTRY_FUNCTION_NOT_PRESENT = 3
BrickletJoystickV2.BOOTLOADER_STATUS_DEVICE_IDENTIFIER_INCORRECT = 4
BrickletJoystickV2.BOOTLOADER_STATUS_CRC_MISMATCH = 5

int BrickletJoystickV2.getBootloaderMode()¶

Returns:	mode – Type: int, Range: See constants

Returns the current bootloader mode, see setBootloaderMode().

The following constants are available for this function:

For mode:

BrickletJoystickV2.BOOTLOADER_MODE_BOOTLOADER = 0
BrickletJoystickV2.BOOTLOADER_MODE_FIRMWARE = 1
BrickletJoystickV2.BOOTLOADER_MODE_BOOTLOADER_WAIT_FOR_REBOOT = 2
BrickletJoystickV2.BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_REBOOT = 3
BrickletJoystickV2.BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_ERASE_AND_REBOOT = 4

void BrickletJoystickV2.setWriteFirmwarePointer(long pointer)¶

Parameters:	pointer – Type: long, Unit: 1 B, Range: [0 to 2³² - 1]

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 BrickletJoystickV2.writeFirmware(int[] data)¶

Parameters:	data – Type: int[], Length: 64, Range: [0 to 255]
Returns:	status – Type: int, Range: [0 to 255]

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 BrickletJoystickV2.writeUID(long uid)¶

Parameters:	uid – Type: long, Range: [0 to 2³² - 1]

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.

long BrickletJoystickV2.readUID()¶

Returns:	uid – Type: long, Range: [0 to 2³² - 1]

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

Constants¶

int BrickletJoystickV2.DEVICE_IDENTIFIER¶

This constant is used to identify a Joystick 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.

String BrickletJoystickV2.DEVICE_DISPLAY_NAME¶: This constant represents the human readable name of a Joystick Bricklet 2.0.