MATLAB/Octave - Load Cell Bricklet¶

Simple (MATLAB)¶

Download (matlab_example_simple.m)

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

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

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

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

    % Get current weight
    weight = lc.getWeight();
    fprintf('Weight: %i g\n', weight);

    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.BrickletLoadCell;

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

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

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

    % Register weight callback to function cb_weight
    set(lc, 'WeightCallback', @(h, e) cb_weight(e));

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

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

% Callback function for weight callback
function cb_weight(e)
    fprintf('Weight: %i g\n', e.weight);
end

Threshold (MATLAB)¶

Download (matlab_example_threshold.m)

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

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

    ipcon = IPConnection(); % Create IP connection
    lc = handle(BrickletLoadCell(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 1 second (1000ms)
    lc.setDebouncePeriod(1000);

    % Register weight reached callback to function cb_weight_reached
    set(lc, 'WeightReachedCallback', @(h, e) cb_weight_reached(e));

    % Configure threshold for weight "greater than 200 g"
    lc.setWeightCallbackThreshold('>', 200, 0);

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

% Callback function for weight reached callback
function cb_weight_reached(e)
    fprintf('Weight: %i g\n', e.weight);
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 Load Cell Bricklet

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

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

    % Get current weight
    weight = lc.getWeight();
    fprintf("Weight: %d g\n", weight);

    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 Load Cell Bricklet

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

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

    % Register weight callback to function cb_weight
    lc.addWeightCallback(@cb_weight);

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

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

% Callback function for weight callback
function cb_weight(e)
    fprintf("Weight: %d g\n", e.weight);
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 Load Cell Bricklet

    ipcon = javaObject("com.tinkerforge.IPConnection"); % Create IP connection
    lc = javaObject("com.tinkerforge.BrickletLoadCell", 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 1 second (1000ms)
    lc.setDebouncePeriod(1000);

    % Register weight reached callback to function cb_weight_reached
    lc.addWeightReachedCallback(@cb_weight_reached);

    % Configure threshold for weight "greater than 200 g"
    lc.setWeightCallbackThreshold(">", 200, 0);

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

% Callback function for weight reached callback
function cb_weight_reached(e)
    fprintf("Weight: %d g\n", e.weight);
end

Basic Functions¶

class BrickletLoadCell(String uid, IPConnection ipcon)¶

Parameters:	uid – Type: String ipcon – Type: IPConnection
Returns:	loadCell – Type: BrickletLoadCell

Creates an object with the unique device ID uid.

In MATLAB:

import com.tinkerforge.BrickletLoadCell;

loadCell = BrickletLoadCell('YOUR_DEVICE_UID', ipcon);

In Octave:

loadCell = java_new("com.tinkerforge.BrickletLoadCell", "YOUR_DEVICE_UID", ipcon);

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

int BrickletLoadCell.getWeight()¶

Returns:	weight – Type: int, Unit: 1 g, Range: [-231 to 231 - 1]

Returns the currently measured weight.

If you want to get the weight periodically, it is recommended to use the WeightCallback callback and set the period with setWeightCallbackPeriod().

void BrickletLoadCell.ledOn()¶

Turns the LED on.

void BrickletLoadCell.ledOff()¶

Turns the LED off.

boolean BrickletLoadCell.isLEDOn()¶

Returns:	on – Type: boolean, Default: false

Returns true if the led is on, false otherwise.

void BrickletLoadCell.tare()¶

Sets the currently measured weight as tare weight.

Advanced Functions¶

void BrickletLoadCell.setMovingAverage(short average)¶

Parameters:	average – Type: short, Range: [1 to 40], Default: 4

Sets the length of a moving averaging for the weight value.

Setting the length to 1 will turn the averaging off. With less averaging, there is more noise on the data.

short BrickletLoadCell.getMovingAverage()¶

Returns:	average – Type: short, Range: [1 to 40], Default: 4

Returns the length moving average as set by setMovingAverage().

void BrickletLoadCell.calibrate(long weight)¶

Parameters:	weight – Type: long, Unit: 1 g, Range: [0 to 232 - 1]

To calibrate your Load Cell Bricklet you have to

• empty the scale and call this function with 0 and
• add a known weight to the scale and call this function with the weight.

The calibration is saved in the EEPROM of the Bricklet and only needs to be done once.

We recommend to use the Brick Viewer for calibration, you don't need to call this function in your source code.

void BrickletLoadCell.setConfiguration(short rate, short gain)¶

Parameters:	rate – Type: short, Range: See constants, Default: 0 gain – Type: short, Range: See constants, Default: 0

The measurement rate and gain are configurable.

The rate can be either 10Hz or 80Hz. A faster rate will produce more noise. It is additionally possible to add a moving average (see setMovingAverage()) to the measurements.

The gain can be 128x, 64x or 32x. It represents a measurement range of ±20mV, ±40mV and ±80mV respectively. The Load Cell Bricklet uses an excitation voltage of 5V and most load cells use an output of 2mV/V. That means the voltage range is ±15mV for most load cells (i.e. gain of 128x is best). If you don't know what all of this means you should keep it at 128x, it will most likely be correct.

The configuration is saved in the EEPROM of the Bricklet and only needs to be done once.

We recommend to use the Brick Viewer for configuration, you don't need to call this function in your source code.

The following constants are available for this function:

For rate:

• BrickletLoadCell.RATE_10HZ = 0
• BrickletLoadCell.RATE_80HZ = 1

For gain:

• BrickletLoadCell.GAIN_128X = 0
• BrickletLoadCell.GAIN_64X = 1
• BrickletLoadCell.GAIN_32X = 2

BrickletLoadCell.Configuration BrickletLoadCell.getConfiguration()¶

Return Object:	rate – Type: short, Range: See constants, Default: 0 gain – Type: short, Range: See constants, Default: 0

Returns the configuration as set by setConfiguration().

The following constants are available for this function:

For rate:

• BrickletLoadCell.RATE_10HZ = 0
• BrickletLoadCell.RATE_80HZ = 1

For gain:

• BrickletLoadCell.GAIN_128X = 0
• BrickletLoadCell.GAIN_64X = 1
• BrickletLoadCell.GAIN_32X = 2

BrickletLoadCell.Identity BrickletLoadCell.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 BrickletLoadCell.setWeightCallbackPeriod(long period)¶

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

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

The WeightCallback callback is only triggered if the weight has changed since the last triggering.

long BrickletLoadCell.getWeightCallbackPeriod()¶

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

Returns the period as set by setWeightCallbackPeriod().

void BrickletLoadCell.setWeightCallbackThreshold(char option, int min, int max)¶

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

Sets the thresholds for the WeightReachedCallback callback.

The following options are possible:

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

The following constants are available for this function:

For option:

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

BrickletLoadCell.WeightCallbackThreshold BrickletLoadCell.getWeightCallbackThreshold()¶

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

Returns the threshold as set by setWeightCallbackThreshold().

The following constants are available for this function:

For option:

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

void BrickletLoadCell.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

• WeightReachedCallback

is triggered, if the threshold

• setWeightCallbackThreshold()

keeps being reached.

long BrickletLoadCell.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 BrickletLoadCell.WeightCallback¶

Event Object:	weight – Type: int, Unit: 1 g, Range: [-231 to 231 - 1]

This callback is triggered periodically with the period that is set by setWeightCallbackPeriod(). The parameter is the weight as measured by the load cell.

The WeightCallback callback is only triggered if the weight 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 addWeightCallback() function. An added callback function can be removed with the removeWeightCallback() function.

callback BrickletLoadCell.WeightReachedCallback¶

Event Object:	weight – Type: int, Unit: 1 g, Range: [-231 to 231 - 1]

This callback is triggered when the threshold as set by setWeightCallbackThreshold() is reached. The parameter is the weight as measured by the load cell.

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 addWeightReachedCallback() function. An added callback function can be removed with the removeWeightReachedCallback() 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[] BrickletLoadCell.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 BrickletLoadCell.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:

• BrickletLoadCell.FUNCTION_SET_WEIGHT_CALLBACK_PERIOD = 2
• BrickletLoadCell.FUNCTION_SET_WEIGHT_CALLBACK_THRESHOLD = 4
• BrickletLoadCell.FUNCTION_SET_DEBOUNCE_PERIOD = 6
• BrickletLoadCell.FUNCTION_SET_MOVING_AVERAGE = 8
• BrickletLoadCell.FUNCTION_LED_ON = 10
• BrickletLoadCell.FUNCTION_LED_OFF = 11
• BrickletLoadCell.FUNCTION_CALIBRATE = 13
• BrickletLoadCell.FUNCTION_TARE = 14
• BrickletLoadCell.FUNCTION_SET_CONFIGURATION = 15

void BrickletLoadCell.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:

• BrickletLoadCell.FUNCTION_SET_WEIGHT_CALLBACK_PERIOD = 2
• BrickletLoadCell.FUNCTION_SET_WEIGHT_CALLBACK_THRESHOLD = 4
• BrickletLoadCell.FUNCTION_SET_DEBOUNCE_PERIOD = 6
• BrickletLoadCell.FUNCTION_SET_MOVING_AVERAGE = 8
• BrickletLoadCell.FUNCTION_LED_ON = 10
• BrickletLoadCell.FUNCTION_LED_OFF = 11
• BrickletLoadCell.FUNCTION_CALIBRATE = 13
• BrickletLoadCell.FUNCTION_TARE = 14
• BrickletLoadCell.FUNCTION_SET_CONFIGURATION = 15

void BrickletLoadCell.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 BrickletLoadCell.DEVICE_IDENTIFIER¶

This constant is used to identify a Load Cell 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 BrickletLoadCell.DEVICE_DISPLAY_NAME¶

This constant represents the human readable name of a Load Cell Bricklet.