MATLAB/Octave - Current25 Bricklet

This is the description of the MATLAB/Octave API bindings for the Current25 Bricklet. General information and technical specifications for the Current25 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).

Simple (MATLAB)

Download (matlab_example_simple.m)

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function matlab_example_simple()
    import com.tinkerforge.IPConnection;
    import com.tinkerforge.BrickletCurrent25;

    HOST = 'localhost';
    PORT = 4223;
    UID = 'XYZ'; % Change XYZ to the UID of your Current25 Bricklet

    ipcon = IPConnection(); % Create IP connection
    c = handle(BrickletCurrent25(UID, ipcon), 'CallbackProperties'); % Create device object

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

    % Get current current
    current = c.getCurrent();
    fprintf('Current: %g A\n', current/1000.0);

    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.BrickletCurrent25;

    HOST = 'localhost';
    PORT = 4223;
    UID = 'XYZ'; % Change XYZ to the UID of your Current25 Bricklet

    ipcon = IPConnection(); % Create IP connection
    c = handle(BrickletCurrent25(UID, ipcon), 'CallbackProperties'); % Create device object

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

    % Register current callback to function cb_current
    set(c, 'CurrentCallback', @(h, e) cb_current(e));

    % Set period for current callback to 1s (1000ms)
    % Note: The current callback is only called every second
    %       if the current has changed since the last call!
    c.setCurrentCallbackPeriod(1000);

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

% Callback function for current callback
function cb_current(e)
    fprintf('Current: %g A\n', e.current/1000.0);
end

Threshold (MATLAB)

Download (matlab_example_threshold.m)

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function matlab_example_threshold()
    import com.tinkerforge.IPConnection;
    import com.tinkerforge.BrickletCurrent25;

    HOST = 'localhost';
    PORT = 4223;
    UID = 'XYZ'; % Change XYZ to the UID of your Current25 Bricklet

    ipcon = IPConnection(); % Create IP connection
    c = handle(BrickletCurrent25(UID, ipcon), 'CallbackProperties'); % Create device object

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

    % Get threshold callbacks with a debounce time of 10 seconds (10000ms)
    c.setDebouncePeriod(10000);

    % Register current reached callback to function cb_current_reached
    set(c, 'CurrentReachedCallback', @(h, e) cb_current_reached(e));

    % Configure threshold for current "greater than 5 A"
    c.setCurrentCallbackThreshold('>', 5*1000, 0);

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

% Callback function for current reached callback
function cb_current_reached(e)
    fprintf('Current: %g A\n', e.current/1000.0);
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 Current25 Bricklet

    ipcon = javaObject("com.tinkerforge.IPConnection"); % Create IP connection
    c = javaObject("com.tinkerforge.BrickletCurrent25", UID, ipcon); % Create device object

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

    % Get current current
    current = c.getCurrent();
    fprintf("Current: %g A\n", java2int(current)/1000.0);

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

function int = java2int(value)
    if compare_versions(version(), "3.8", "<=")
        int = value.intValue();
    else
        int = value;
    end
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 Current25 Bricklet

    ipcon = javaObject("com.tinkerforge.IPConnection"); % Create IP connection
    c = javaObject("com.tinkerforge.BrickletCurrent25", UID, ipcon); % Create device object

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

    % Register current callback to function cb_current
    c.addCurrentCallback(@cb_current);

    % Set period for current callback to 1s (1000ms)
    % Note: The current callback is only called every second
    %       if the current has changed since the last call!
    c.setCurrentCallbackPeriod(1000);

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

% Callback function for current callback
function cb_current(e)
    fprintf("Current: %g A\n", java2int(e.current)/1000.0);
end

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

Threshold (Octave)

Download (octave_example_threshold.m)

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function octave_example_threshold()
    more off;

    HOST = "localhost";
    PORT = 4223;
    UID = "XYZ"; % Change XYZ to the UID of your Current25 Bricklet

    ipcon = javaObject("com.tinkerforge.IPConnection"); % Create IP connection
    c = javaObject("com.tinkerforge.BrickletCurrent25", UID, ipcon); % Create device object

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

    % Get threshold callbacks with a debounce time of 10 seconds (10000ms)
    c.setDebouncePeriod(10000);

    % Register current reached callback to function cb_current_reached
    c.addCurrentReachedCallback(@cb_current_reached);

    % Configure threshold for current "greater than 5 A"
    c.setCurrentCallbackThreshold(">", 5*1000, 0);

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

% Callback function for current reached callback
function cb_current_reached(e)
    fprintf("Current: %g A\n", java2int(e.current)/1000.0);
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

class BrickletCurrent25(String uid, IPConnection ipcon)
Parameters:
  • uid – Type: String
  • ipcon – Type: IPConnection
Returns:
  • current25 – Type: BrickletCurrent25

Creates an object with the unique device ID uid.

In MATLAB:

import com.tinkerforge.BrickletCurrent25;

current25 = BrickletCurrent25('YOUR_DEVICE_UID', ipcon);

In Octave:

current25 = java_new("com.tinkerforge.BrickletCurrent25", "YOUR_DEVICE_UID", ipcon);

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

short BrickletCurrent25.getCurrent()
Returns:
  • current – Type: short, Range: [-215 to 215 - 1]

Returns the current of the sensor. The value is in mA and between -25000mA and 25000mA.

If you want to get the current periodically, it is recommended to use the CurrentCallback callback and set the period with setCurrentCallbackPeriod().

Advanced Functions

void BrickletCurrent25.calibrate()

Calibrates the 0 value of the sensor. You have to call this function when there is no current present.

The zero point of the current sensor is depending on the exact properties of the analog-to-digital converter, the length of the Bricklet cable and the temperature. Thus, if you change the Brick or the environment in which the Bricklet is used, you might have to recalibrate.

The resulting calibration will be saved on the EEPROM of the Current Bricklet.

boolean BrickletCurrent25.isOverCurrent()
Returns:
  • over – Type: boolean

Returns true if more than 25A were measured.

Note

To reset this value you have to power cycle the Bricklet.

int BrickletCurrent25.getAnalogValue()
Returns:
  • value – Type: int, Range: [0 to 216 - 1]

Returns the value as read by a 12-bit analog-to-digital converter. The value is between 0 and 4095.

Note

The value returned by getCurrent() is averaged over several samples to yield less noise, while getAnalogValue() gives back raw unfiltered analog values. The only reason to use getAnalogValue() is, if you need the full resolution of the analog-to-digital converter.

If you want the analog value periodically, it is recommended to use the AnalogValueCallback callback and set the period with setAnalogValueCallbackPeriod().

short[] BrickletCurrent25.getAPIVersion()
Returns:
  • apiVersion – Type: short[], Length: 3, Range: [0 to 255]

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.

boolean BrickletCurrent25.getResponseExpected(short functionId)
Parameters:
  • functionId – Type: short, 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 send and errors are silently ignored, because they cannot be detected.

The following constants are available for this function:

For functionId:

  • BrickletCurrent25.FUNCTION_CALIBRATE = 2
  • BrickletCurrent25.FUNCTION_SET_CURRENT_CALLBACK_PERIOD = 5
  • BrickletCurrent25.FUNCTION_SET_ANALOG_VALUE_CALLBACK_PERIOD = 7
  • BrickletCurrent25.FUNCTION_SET_CURRENT_CALLBACK_THRESHOLD = 9
  • BrickletCurrent25.FUNCTION_SET_ANALOG_VALUE_CALLBACK_THRESHOLD = 11
  • BrickletCurrent25.FUNCTION_SET_DEBOUNCE_PERIOD = 13
void BrickletCurrent25.setResponseExpected(short functionId, boolean responseExpected)
Parameters:
  • functionId – Type: short, 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 send and errors are silently ignored, because they cannot be detected.

The following constants are available for this function:

For functionId:

  • BrickletCurrent25.FUNCTION_CALIBRATE = 2
  • BrickletCurrent25.FUNCTION_SET_CURRENT_CALLBACK_PERIOD = 5
  • BrickletCurrent25.FUNCTION_SET_ANALOG_VALUE_CALLBACK_PERIOD = 7
  • BrickletCurrent25.FUNCTION_SET_CURRENT_CALLBACK_THRESHOLD = 9
  • BrickletCurrent25.FUNCTION_SET_ANALOG_VALUE_CALLBACK_THRESHOLD = 11
  • BrickletCurrent25.FUNCTION_SET_DEBOUNCE_PERIOD = 13
void BrickletCurrent25.setResponseExpectedAll(boolean responseExpected)
Parameters:
  • responseExpected – Type: boolean

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

BrickletCurrent25.Identity BrickletCurrent25.getIdentity()
Return Object:
  • uid – Type: String, Length: up to 8
  • connectedUid – Type: String, Length: up to 8
  • position – Type: char
  • hardwareVersion – Type: short[], Length: 3, Range: [0 to 255]
  • firmwareVersion – Type: short[], Length: 3, 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' or 'd'.

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

Callback Configuration Functions

void BrickletCurrent25.setCurrentCallbackPeriod(long period)
Parameters:
  • period – Type: long, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0

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

The CurrentCallback callback is only triggered if the current has changed since the last triggering.

long BrickletCurrent25.getCurrentCallbackPeriod()
Returns:
  • period – Type: long, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0

Returns the period as set by setCurrentCallbackPeriod().

void BrickletCurrent25.setAnalogValueCallbackPeriod(long period)
Parameters:
  • period – Type: long, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0

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

The AnalogValueCallback callback is only triggered if the analog value has changed since the last triggering.

long BrickletCurrent25.getAnalogValueCallbackPeriod()
Returns:
  • period – Type: long, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0

Returns the period as set by setAnalogValueCallbackPeriod().

void BrickletCurrent25.setCurrentCallbackThreshold(char option, short min, short max)
Parameters:
  • option – Type: char, Range: See constants, Default: 'x'
  • min – Type: short, Range: [-215 to 215 - 1]
  • max – Type: short, Range: [-215 to 215 - 1]

Sets the thresholds for the CurrentReachedCallback callback.

The following options are possible:

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

The default value is ('x', 0, 0).

The following constants are available for this function:

For option:

  • BrickletCurrent25.THRESHOLD_OPTION_OFF = 'x'
  • BrickletCurrent25.THRESHOLD_OPTION_OUTSIDE = 'o'
  • BrickletCurrent25.THRESHOLD_OPTION_INSIDE = 'i'
  • BrickletCurrent25.THRESHOLD_OPTION_SMALLER = '<'
  • BrickletCurrent25.THRESHOLD_OPTION_GREATER = '>'
BrickletCurrent25.CurrentCallbackThreshold BrickletCurrent25.getCurrentCallbackThreshold()
Return Object:
  • option – Type: char, Range: See constants, Default: 'x'
  • min – Type: short, Range: [-215 to 215 - 1]
  • max – Type: short, Range: [-215 to 215 - 1]

Returns the threshold as set by setCurrentCallbackThreshold().

The following constants are available for this function:

For option:

  • BrickletCurrent25.THRESHOLD_OPTION_OFF = 'x'
  • BrickletCurrent25.THRESHOLD_OPTION_OUTSIDE = 'o'
  • BrickletCurrent25.THRESHOLD_OPTION_INSIDE = 'i'
  • BrickletCurrent25.THRESHOLD_OPTION_SMALLER = '<'
  • BrickletCurrent25.THRESHOLD_OPTION_GREATER = '>'
void BrickletCurrent25.setAnalogValueCallbackThreshold(char option, int min, int max)
Parameters:
  • option – Type: char, Range: See constants, Default: 'x'
  • min – Type: int, Range: [0 to 216 - 1]
  • max – Type: int, Range: [0 to 216 - 1]

Sets the thresholds for the AnalogValueReachedCallback callback.

The following options are possible:

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

The default value is ('x', 0, 0).

The following constants are available for this function:

For option:

  • BrickletCurrent25.THRESHOLD_OPTION_OFF = 'x'
  • BrickletCurrent25.THRESHOLD_OPTION_OUTSIDE = 'o'
  • BrickletCurrent25.THRESHOLD_OPTION_INSIDE = 'i'
  • BrickletCurrent25.THRESHOLD_OPTION_SMALLER = '<'
  • BrickletCurrent25.THRESHOLD_OPTION_GREATER = '>'
BrickletCurrent25.AnalogValueCallbackThreshold BrickletCurrent25.getAnalogValueCallbackThreshold()
Return Object:
  • option – Type: char, Range: See constants, Default: 'x'
  • min – Type: int, Range: [0 to 216 - 1]
  • max – Type: int, Range: [0 to 216 - 1]

Returns the threshold as set by setAnalogValueCallbackThreshold().

The following constants are available for this function:

For option:

  • BrickletCurrent25.THRESHOLD_OPTION_OFF = 'x'
  • BrickletCurrent25.THRESHOLD_OPTION_OUTSIDE = 'o'
  • BrickletCurrent25.THRESHOLD_OPTION_INSIDE = 'i'
  • BrickletCurrent25.THRESHOLD_OPTION_SMALLER = '<'
  • BrickletCurrent25.THRESHOLD_OPTION_GREATER = '>'
void BrickletCurrent25.setDebouncePeriod(long debounce)
Parameters:
  • debounce – Type: long, Unit: 1 ms, Range: [0 to 232 - 1], Default: 100

Sets the period with which the threshold callbacks

are triggered, if the thresholds

keep being reached.

long BrickletCurrent25.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.

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 BrickletCurrent25.CurrentCallback
Event Object:
  • current – Type: short, Range: [-215 to 215 - 1]

This callback is triggered periodically with the period that is set by setCurrentCallbackPeriod(). The parameter is the current of the sensor.

The CurrentCallback callback is only triggered if the current 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 addCurrentCallback() function. An added callback function can be removed with the removeCurrentCallback() function.

callback BrickletCurrent25.AnalogValueCallback
Event Object:
  • value – Type: int, Range: [0 to 216 - 1]

This callback is triggered periodically with the period that is set by setAnalogValueCallbackPeriod(). The parameter is the analog value of the sensor.

The AnalogValueCallback callback is only triggered if the current 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 addAnalogValueCallback() function. An added callback function can be removed with the removeAnalogValueCallback() function.

callback BrickletCurrent25.CurrentReachedCallback
Event Object:
  • current – Type: short, Range: [-215 to 215 - 1]

This callback is triggered when the threshold as set by setCurrentCallbackThreshold() is reached. The parameter is the current of the sensor.

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 addCurrentReachedCallback() function. An added callback function can be removed with the removeCurrentReachedCallback() function.

callback BrickletCurrent25.AnalogValueReachedCallback
Event Object:
  • value – Type: int, Range: [0 to 216 - 1]

This callback is triggered when the threshold as set by setAnalogValueCallbackThreshold() is reached. The parameter is the analog value of the sensor.

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 addAnalogValueReachedCallback() function. An added callback function can be removed with the removeAnalogValueReachedCallback() function.

callback BrickletCurrent25.OverCurrentCallback
Event Object:
  • empty object

This callback is triggered when an over current is measured (see isOverCurrent()).

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 addOverCurrentCallback() function. An added callback function can be removed with the removeOverCurrentCallback() function.

Constants

int BrickletCurrent25.DEVICE_IDENTIFIER

This constant is used to identify a Current25 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 BrickletCurrent25.DEVICE_DISPLAY_NAME

This constant represents the human readable name of a Current25 Bricklet.