MATLAB/Octave - Thermocouple Bricklet

This is the description of the MATLAB/Octave API bindings for the Thermocouple Bricklet. General information and technical specifications for the Thermocouple 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.BrickletThermocouple;

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

    ipcon = IPConnection(); % Create IP connection
    t = handle(BrickletThermocouple(UID, ipcon), 'CallbackProperties'); % Create device object

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

    % Get current temperature
    temperature = t.getTemperature();
    fprintf('Temperature: %g °C\n', temperature/100.0);

    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.BrickletThermocouple;

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

    ipcon = IPConnection(); % Create IP connection
    t = handle(BrickletThermocouple(UID, ipcon), 'CallbackProperties'); % Create device object

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

    % Register temperature callback to function cb_temperature
    set(t, 'TemperatureCallback', @(h, e) cb_temperature(e));

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

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

% Callback function for temperature callback
function cb_temperature(e)
    fprintf('Temperature: %g °C\n', e.temperature/100.0);
end

Threshold (MATLAB)

Download (matlab_example_threshold.m)

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

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

    ipcon = IPConnection(); % Create IP connection
    t = handle(BrickletThermocouple(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)
    t.setDebouncePeriod(10000);

    % Register temperature reached callback to function cb_temperature_reached
    set(t, 'TemperatureReachedCallback', @(h, e) cb_temperature_reached(e));

    % Configure threshold for temperature "greater than 30 °C"
    t.setTemperatureCallbackThreshold('>', 30*100, 0);

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

% Callback function for temperature reached callback
function cb_temperature_reached(e)
    fprintf('Temperature: %g °C\n', e.temperature/100.0);
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 Thermocouple Bricklet

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

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

    % Get current temperature
    temperature = t.getTemperature();
    fprintf("Temperature: %g °C\n", temperature/100.0);

    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 Thermocouple Bricklet

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

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

    % Register temperature callback to function cb_temperature
    t.addTemperatureCallback(@cb_temperature);

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

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

% Callback function for temperature callback
function cb_temperature(e)
    fprintf("Temperature: %g °C\n", e.temperature/100.0);
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 Thermocouple Bricklet

    ipcon = javaObject("com.tinkerforge.IPConnection"); % Create IP connection
    t = javaObject("com.tinkerforge.BrickletThermocouple", 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)
    t.setDebouncePeriod(10000);

    % Register temperature reached callback to function cb_temperature_reached
    t.addTemperatureReachedCallback(@cb_temperature_reached);

    % Configure threshold for temperature "greater than 30 °C"
    t.setTemperatureCallbackThreshold(">", 30*100, 0);

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

% Callback function for temperature reached callback
function cb_temperature_reached(e)
    fprintf("Temperature: %g °C\n", e.temperature/100.0);
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 BrickletThermocouple(String uid, IPConnection ipcon)
Parameters:
  • uid – Type: String
  • ipcon – Type: IPConnection
Returns:
  • thermocouple – Type: BrickletThermocouple

Creates an object with the unique device ID uid.

In MATLAB:

import com.tinkerforge.BrickletThermocouple;

thermocouple = BrickletThermocouple('YOUR_DEVICE_UID', ipcon);

In Octave:

thermocouple = java_new("com.tinkerforge.BrickletThermocouple", "YOUR_DEVICE_UID", ipcon);

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

int BrickletThermocouple.getTemperature()
Returns:
  • temperature – Type: int, Range: [-231 to 231 - 1]

Returns the temperature of the thermocouple. The value is given in °C/100, e.g. a value of 4223 means that a temperature of 42.23 °C is measured.

If you want to get the temperature periodically, it is recommended to use the TemperatureCallback callback and set the period with setTemperatureCallbackPeriod().

Advanced Functions

void BrickletThermocouple.setConfiguration(short averaging, short thermocoupleType, short filter)
Parameters:
  • averaging – Type: short, Range: See constants
  • thermocoupleType – Type: short, Range: See constants
  • filter – Type: short, Range: See constants

You can configure averaging size, thermocouple type and frequency filtering.

Available averaging sizes are 1, 2, 4, 8 and 16 samples.

As thermocouple type you can use B, E, J, K, N, R, S and T. If you have a different thermocouple or a custom thermocouple you can also use G8 and G32. With these types the returned value will not be in °C/100, it will be calculated by the following formulas:

  • G8: value = 8 * 1.6 * 2^17 * Vin
  • G32: value = 32 * 1.6 * 2^17 * Vin

where Vin is the thermocouple input voltage.

The frequency filter can be either configured to 50Hz or to 60Hz. You should configure it according to your utility frequency.

The conversion time depends on the averaging and filter configuration, it can be calculated as follows:

  • 60Hz: time = 82 + (samples - 1) * 16.67
  • 50Hz: time = 98 + (samples - 1) * 20

The default configuration is 16 samples, K type and 50Hz.

The following constants are available for this function:

For averaging:

  • BrickletThermocouple.AVERAGING_1 = 1
  • BrickletThermocouple.AVERAGING_2 = 2
  • BrickletThermocouple.AVERAGING_4 = 4
  • BrickletThermocouple.AVERAGING_8 = 8
  • BrickletThermocouple.AVERAGING_16 = 16

For thermocoupleType:

  • BrickletThermocouple.TYPE_B = 0
  • BrickletThermocouple.TYPE_E = 1
  • BrickletThermocouple.TYPE_J = 2
  • BrickletThermocouple.TYPE_K = 3
  • BrickletThermocouple.TYPE_N = 4
  • BrickletThermocouple.TYPE_R = 5
  • BrickletThermocouple.TYPE_S = 6
  • BrickletThermocouple.TYPE_T = 7
  • BrickletThermocouple.TYPE_G8 = 8
  • BrickletThermocouple.TYPE_G32 = 9

For filter:

  • BrickletThermocouple.FILTER_OPTION_50HZ = 0
  • BrickletThermocouple.FILTER_OPTION_60HZ = 1
BrickletThermocouple.Configuration BrickletThermocouple.getConfiguration()
Return Object:
  • averaging – Type: short, Range: See constants
  • thermocoupleType – Type: short, Range: See constants
  • filter – Type: short, Range: See constants

Returns the configuration as set by setConfiguration().

The following constants are available for this function:

For averaging:

  • BrickletThermocouple.AVERAGING_1 = 1
  • BrickletThermocouple.AVERAGING_2 = 2
  • BrickletThermocouple.AVERAGING_4 = 4
  • BrickletThermocouple.AVERAGING_8 = 8
  • BrickletThermocouple.AVERAGING_16 = 16

For thermocoupleType:

  • BrickletThermocouple.TYPE_B = 0
  • BrickletThermocouple.TYPE_E = 1
  • BrickletThermocouple.TYPE_J = 2
  • BrickletThermocouple.TYPE_K = 3
  • BrickletThermocouple.TYPE_N = 4
  • BrickletThermocouple.TYPE_R = 5
  • BrickletThermocouple.TYPE_S = 6
  • BrickletThermocouple.TYPE_T = 7
  • BrickletThermocouple.TYPE_G8 = 8
  • BrickletThermocouple.TYPE_G32 = 9

For filter:

  • BrickletThermocouple.FILTER_OPTION_50HZ = 0
  • BrickletThermocouple.FILTER_OPTION_60HZ = 1
BrickletThermocouple.ErrorState BrickletThermocouple.getErrorState()
Return Object:
  • overUnder – Type: boolean
  • openCircuit – Type: boolean

Returns the current error state. There are two possible errors:

  • Over/Under Voltage and
  • Open Circuit.

Over/Under Voltage happens for voltages below 0V or above 3.3V. In this case it is very likely that your thermocouple is defective. An Open Circuit error indicates that there is no thermocouple connected.

You can use the ErrorStateCallback callback to automatically get triggered when the error state changes.

short[] BrickletThermocouple.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 BrickletThermocouple.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:

  • BrickletThermocouple.FUNCTION_SET_TEMPERATURE_CALLBACK_PERIOD = 2
  • BrickletThermocouple.FUNCTION_SET_TEMPERATURE_CALLBACK_THRESHOLD = 4
  • BrickletThermocouple.FUNCTION_SET_DEBOUNCE_PERIOD = 6
  • BrickletThermocouple.FUNCTION_SET_CONFIGURATION = 10
void BrickletThermocouple.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:

  • BrickletThermocouple.FUNCTION_SET_TEMPERATURE_CALLBACK_PERIOD = 2
  • BrickletThermocouple.FUNCTION_SET_TEMPERATURE_CALLBACK_THRESHOLD = 4
  • BrickletThermocouple.FUNCTION_SET_DEBOUNCE_PERIOD = 6
  • BrickletThermocouple.FUNCTION_SET_CONFIGURATION = 10
void BrickletThermocouple.setResponseExpectedAll(boolean responseExpected)
Parameters:
  • responseExpected – Type: boolean

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

BrickletThermocouple.Identity BrickletThermocouple.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 BrickletThermocouple.setTemperatureCallbackPeriod(long period)
Parameters:
  • period – Type: long, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0

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

The TemperatureCallback callback is only triggered if the temperature has changed since the last triggering.

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

Returns the period as set by setTemperatureCallbackPeriod().

void BrickletThermocouple.setTemperatureCallbackThreshold(char option, int min, int max)
Parameters:
  • option – Type: char, Range: See constants, Default: 'x'
  • min – Type: int, Range: [-231 to 231 - 1]
  • max – Type: int, Range: [-231 to 231 - 1]

Sets the thresholds for the TemperatureReachedCallback callback.

The following options are possible:

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

  • BrickletThermocouple.THRESHOLD_OPTION_OFF = 'x'
  • BrickletThermocouple.THRESHOLD_OPTION_OUTSIDE = 'o'
  • BrickletThermocouple.THRESHOLD_OPTION_INSIDE = 'i'
  • BrickletThermocouple.THRESHOLD_OPTION_SMALLER = '<'
  • BrickletThermocouple.THRESHOLD_OPTION_GREATER = '>'
BrickletThermocouple.TemperatureCallbackThreshold BrickletThermocouple.getTemperatureCallbackThreshold()
Return Object:
  • option – Type: char, Range: See constants, Default: 'x'
  • min – Type: int, Range: [-231 to 231 - 1]
  • max – Type: int, Range: [-231 to 231 - 1]

Returns the threshold as set by setTemperatureCallbackThreshold().

The following constants are available for this function:

For option:

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

is triggered, if the threshold

keeps being reached.

long BrickletThermocouple.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 BrickletThermocouple.TemperatureCallback
Event Object:
  • temperature – Type: int, Range: [-231 to 231 - 1]

This callback is triggered periodically with the period that is set by setTemperatureCallbackPeriod(). The parameter is the temperature of the thermocouple.

The TemperatureCallback callback is only triggered if the temperature 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 addTemperatureCallback() function. An added callback function can be removed with the removeTemperatureCallback() function.

callback BrickletThermocouple.TemperatureReachedCallback
Event Object:
  • temperature – Type: int, Range: [-231 to 231 - 1]

This callback is triggered when the threshold as set by setTemperatureCallbackThreshold() is reached. The parameter is the temperature of the thermocouple.

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 addTemperatureReachedCallback() function. An added callback function can be removed with the removeTemperatureReachedCallback() function.

callback BrickletThermocouple.ErrorStateCallback
Event Object:
  • overUnder – Type: boolean
  • openCircuit – Type: boolean

This Callback is triggered every time the error state changes (see getErrorState()).

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 addErrorStateCallback() function. An added callback function can be removed with the removeErrorStateCallback() function.

Constants

int BrickletThermocouple.DEVICE_IDENTIFIER

This constant is used to identify a Thermocouple 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 BrickletThermocouple.DEVICE_DISPLAY_NAME

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