MATLAB/Octave - Rotary Encoder Bricklet¶

Simple (MATLAB)¶

Download (matlab_example_simple.m)

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

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

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

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

    % Get current count without reset
    count = re.getCount(false);
    fprintf('Count: %i\n', count);

    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.BrickletRotaryEncoder;

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

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

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

    % Register count callback to function cb_count
    set(re, 'CountCallback', @(h, e) cb_count(e));

    % Set period for count callback to 0.05s (50ms)
    % Note: The count callback is only called every 0.05 seconds
    %       if the count has changed since the last call!
    re.setCountCallbackPeriod(50);

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

% Callback function for count callback
function cb_count(e)
    fprintf('Count: %i\n', e.count);
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 Rotary Encoder Bricklet

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

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

    % Get current count without reset
    count = re.getCount(false);
    fprintf("Count: %d\n", count);

    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 Rotary Encoder Bricklet

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

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

    % Register count callback to function cb_count
    re.addCountCallback(@cb_count);

    % Set period for count callback to 0.05s (50ms)
    % Note: The count callback is only called every 0.05 seconds
    %       if the count has changed since the last call!
    re.setCountCallbackPeriod(50);

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

% Callback function for count callback
function cb_count(e)
    fprintf("Count: %d\n", e.count);
end

Basic Functions¶

class BrickletRotaryEncoder(String uid, IPConnection ipcon)¶

Parameters:	uid – Type: String ipcon – Type: IPConnection
Returns:	rotaryEncoder – Type: BrickletRotaryEncoder

Creates an object with the unique device ID uid.

In MATLAB:

import com.tinkerforge.BrickletRotaryEncoder;

rotaryEncoder = BrickletRotaryEncoder('YOUR_DEVICE_UID', ipcon);

In Octave:

rotaryEncoder = java_new("com.tinkerforge.BrickletRotaryEncoder", "YOUR_DEVICE_UID", ipcon);

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

int BrickletRotaryEncoder.getCount(boolean reset)¶

Parameters:	reset – Type: boolean
Returns:	count – Type: int, Range: [-231 to 231 - 1]

Returns the current count of the encoder. If you set reset to true, the count is set back to 0 directly after the current count is read.

The encoder has 24 steps per rotation

Turning the encoder to the left decrements the counter, so a negative count is possible.

boolean BrickletRotaryEncoder.isPressed()¶

Returns:	pressed – Type: boolean

Returns true if the button is pressed and false otherwise.

It is recommended to use the PressedCallback and ReleasedCallback callbacks to handle the button.

Advanced Functions¶

BrickletRotaryEncoder.Identity BrickletRotaryEncoder.getIdentity()¶

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]

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 BrickletRotaryEncoder.setCountCallbackPeriod(long period)¶

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

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

The CountCallback callback is only triggered if the count has changed since the last triggering.

long BrickletRotaryEncoder.getCountCallbackPeriod()¶

Returns:	period – Type: long, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0

Returns the period as set by setCountCallbackPeriod().

void BrickletRotaryEncoder.setCountCallbackThreshold(char option, int min, int max)¶

Parameters:	option – Type: char, Range: See constants, Default: 'x' min – Type: int, Range: [-231 to 231 - 1], Default: 0 max – Type: int, Range: [-231 to 231 - 1], Default: 0

Sets the thresholds for the CountReachedCallback callback.

The following options are possible:

Option	Description
'x'	Callback is turned off
'o'	Callback is triggered when the count is outside the min and max values
'i'	Callback is triggered when the count is inside the min and max values
'<'	Callback is triggered when the count is smaller than the min value (max is ignored)
'>'	Callback is triggered when the count is greater than the min value (max is ignored)

The following constants are available for this function:

For option:

• BrickletRotaryEncoder.THRESHOLD_OPTION_OFF = 'x'
• BrickletRotaryEncoder.THRESHOLD_OPTION_OUTSIDE = 'o'
• BrickletRotaryEncoder.THRESHOLD_OPTION_INSIDE = 'i'
• BrickletRotaryEncoder.THRESHOLD_OPTION_SMALLER = '<'
• BrickletRotaryEncoder.THRESHOLD_OPTION_GREATER = '>'

BrickletRotaryEncoder.CountCallbackThreshold BrickletRotaryEncoder.getCountCallbackThreshold()¶

Return Object:	option – Type: char, Range: See constants, Default: 'x' min – Type: int, Range: [-231 to 231 - 1], Default: 0 max – Type: int, Range: [-231 to 231 - 1], Default: 0

Returns the threshold as set by setCountCallbackThreshold().

The following constants are available for this function:

For option:

• BrickletRotaryEncoder.THRESHOLD_OPTION_OFF = 'x'
• BrickletRotaryEncoder.THRESHOLD_OPTION_OUTSIDE = 'o'
• BrickletRotaryEncoder.THRESHOLD_OPTION_INSIDE = 'i'
• BrickletRotaryEncoder.THRESHOLD_OPTION_SMALLER = '<'
• BrickletRotaryEncoder.THRESHOLD_OPTION_GREATER = '>'

void BrickletRotaryEncoder.setDebouncePeriod(long debounce)¶

Parameters:	debounce – Type: long, Unit: 1 ms, Range: [0 to 232 - 1], Default: 100

Sets the period with which the threshold callback

• CountReachedCallback

is triggered, if the thresholds

• setCountCallbackThreshold()

keeps being reached.

long BrickletRotaryEncoder.getDebouncePeriod()¶

Returns:	debounce – Type: long, Unit: 1 ms, Range: [0 to 232 - 1], Default: 100

Returns the debounce period as set by setDebouncePeriod().

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.

callback BrickletRotaryEncoder.CountCallback¶

Event Object:	count – Type: int, Range: [-231 to 231 - 1]

This callback is triggered periodically with the period that is set by setCountCallbackPeriod(). The parameter is the count of the encoder.

The CountCallback callback is only triggered if the count has changed since the last triggering.

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 addCountCallback() function. An added callback function can be removed with the removeCountCallback() function.

callback BrickletRotaryEncoder.CountReachedCallback¶

Event Object:	count – Type: int, Range: [-231 to 231 - 1]

This callback is triggered when the threshold as set by setCountCallbackThreshold() is reached. The parameter is the count of the encoder.

If the threshold keeps being reached, the callback is triggered periodically with the period as set by setDebouncePeriod().

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 addCountReachedCallback() function. An added callback function can be removed with the removeCountReachedCallback() function.

callback BrickletRotaryEncoder.PressedCallback¶

Event Object:	empty object

This callback is triggered when the button is pressed.

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.

callback BrickletRotaryEncoder.ReleasedCallback¶

Event Object:	empty object

This callback is triggered when the button is released.

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 addReleasedCallback() function. An added callback function can be removed with the removeReleasedCallback() 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[] BrickletRotaryEncoder.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 BrickletRotaryEncoder.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:

• BrickletRotaryEncoder.FUNCTION_SET_COUNT_CALLBACK_PERIOD = 2
• BrickletRotaryEncoder.FUNCTION_SET_COUNT_CALLBACK_THRESHOLD = 4
• BrickletRotaryEncoder.FUNCTION_SET_DEBOUNCE_PERIOD = 6

void BrickletRotaryEncoder.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.

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:

• BrickletRotaryEncoder.FUNCTION_SET_COUNT_CALLBACK_PERIOD = 2
• BrickletRotaryEncoder.FUNCTION_SET_COUNT_CALLBACK_THRESHOLD = 4
• BrickletRotaryEncoder.FUNCTION_SET_DEBOUNCE_PERIOD = 6

void BrickletRotaryEncoder.setResponseExpectedAll(boolean responseExpected)¶

Parameters:	responseExpected – Type: boolean

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

Constants¶

int BrickletRotaryEncoder.DEVICE_IDENTIFIER¶

This constant is used to identify a Rotary Encoder Bricklet.

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 BrickletRotaryEncoder.DEVICE_DISPLAY_NAME¶

This constant represents the human readable name of a Rotary Encoder Bricklet.