MATLAB/Octave - Voltage Bricklet – Tinkerforge

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# MATLAB/Octave - Voltage Bricklet

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

        HOST = 'localhost';
        PORT = 4223;
        UID = 'abd2'; % Change to your UID

        ipcon = IPConnection(); % Create IP connection
        v = BrickletVoltage(UID, ipcon); % Create device object

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

        % Get current voltage (unit is mV)
        voltage = v.getVoltage();
        fprintf('Voltage: %g V', voltage/1000.0);

        input('Press any 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.BrickletVoltage;

        HOST = 'localhost';
        PORT = 4223;
        UID = 'abd2'; % Change to your UID

        ipcon = IPConnection(); % Create IP connection
        v = BrickletVoltage(UID, ipcon); % Create device object

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

        % Set Period for voltage callback to 1s (1000ms)
        % Note: The callback is only called every second if the
        %       voltage has changed since the last call!
        v.setVoltageCallbackPeriod(1000);

        % Register voltage callback to function cb_voltage
        set(v, 'VoltageCallback', @(h, e) cb_voltage(e));

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

    % Callback function for voltage callback (parameter has unit mV)
    function cb_voltage(e)
        fprintf('Voltage: %g V\n', e.voltage/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.BrickletVoltage;

        HOST = 'localhost';
        PORT = 4223;
        UID = 'abd2'; % Change to your UID

        ipcon = IPConnection(); % Create IP connection
        v = BrickletVoltage(UID, ipcon); % Create device object

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

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

        % Register threshold reached callback to function cb_reached
        set(v, 'VoltageReachedCallback', @(h, e) cb_reached(e));

        % Configure threshold for "smaller than 5V" (unit is mV)
        v.setVoltageCallbackThreshold('<', 5*1000, 0);

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

    % Callback for voltage greater than 5V
    function cb_reached(e)
        fprintf('Voltage dropped below 5V: %g\n', e.voltage/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 = "abd2"; % Change to your UID

        ipcon = java_new("com.tinkerforge.IPConnection"); % Create IP connection
        v = java_new("com.tinkerforge.BrickletVoltage", UID, ipcon); % Create device object

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

        % Get current voltage (unit is mV)
        voltage = v.getVoltage();
        fprintf("Voltage: %g V\n", voltage/1000.0);

        input("Press any 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 = "abd2"; % Change to your UID

        ipcon = java_new("com.tinkerforge.IPConnection"); % Create IP connection
        v = java_new("com.tinkerforge.BrickletVoltage", UID, ipcon); % Create device object

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

        % Set Period for voltage callback to 1s (1000ms)
        % Note: The callback is only called every second if the
        %       voltage has changed since the last call!
        v.setVoltageCallbackPeriod(1000);

        % Register voltage callback to function cb_voltage
        v.addVoltageCallback(@cb_voltage);

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

    % Callback function for voltage callback (parameter has unit mV)
    function cb_voltage(e)
        fprintf("Voltage: %g V\n", e.voltage/1000.0);
    end

### Threshold (Octave)

Download (octave_example_threshold.m)

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    function octave_example_threshold()
        more off;

        HOST = "localhost";
        PORT = 4223;
        UID = "abd2"; % Change to your UID

        ipcon = java_new("com.tinkerforge.IPConnection"); % Create IP connection
        v = java_new("com.tinkerforge.BrickletVoltage", UID, ipcon); % Create device object

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

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

        % Register threshold reached callback to function cb_reached
        v.addVoltageReachedCallback(@cb_reached);

        % Configure threshold for "smaller than 5V" (unit is mV)
        v.setVoltageCallbackThreshold(v.THRESHOLD_OPTION_SMALLER, 5*1000, 0);

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

    % Callback for voltage less than 5V
    function cb_reached(e)
        fprintf("Voltage dropped below 5V: %g\n", e.voltage/1000.0);
    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

public class `BrickletVoltage`(String uid, IPConnection ipcon)

  Creates an object with the unique device ID `uid`.

  In MATLAB:

      import com.tinkerforge.BrickletVoltage;

      voltage = BrickletVoltage('YOUR_DEVICE_UID', ipcon);

  In Octave:

      voltage = java_new("com.tinkerforge.BrickletVoltage", "YOUR_DEVICE_UID", ipcon);

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

public int `getVoltage`()

  Returns the voltage of the sensor. The value is in mV and between 0mV and 50000mV.

  If you want to get the voltage periodically, it is recommended to use the callback `VoltageCallback` and set the period with `setVoltageCallbackPeriod()`.

### Advanced Functions

public int `getAnalogValue`()

  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 `getVoltage()` 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 callback `AnalogValueCallback` and set the period with `setAnalogValueCallbackPeriod()`.

public short[] `getAPIVersion`()

  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.

public boolean `getResponseExpected`(short functionId)

  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.

  See `setResponseExpected()` for the list of function ID constants available for this function.

public void `setResponseExpected`(short functionId, boolean responseExpected)

  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 and callbacks it is always disabled.

  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 function ID constants are available for this function:

  - BrickletVoltage.FUNCTION_SET_VOLTAGE_CALLBACK_PERIOD = 3
  - BrickletVoltage.FUNCTION_SET_ANALOG_VALUE_CALLBACK_PERIOD = 5
  - BrickletVoltage.FUNCTION_SET_VOLTAGE_CALLBACK_THRESHOLD = 7
  - BrickletVoltage.FUNCTION_SET_ANALOG_VALUE_CALLBACK_THRESHOLD = 9
  - BrickletVoltage.FUNCTION_SET_DEBOUNCE_PERIOD = 11

public void `setResponseExpectedAll`(boolean responseExpected)

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

public BrickletVoltage.Identity `getIdentity`()

  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.

  The returned object has the public member variables `String uid`, `String connectedUid`, `char position`, `short[] hardwareVersion`, `short[] firmwareVersion` and `int deviceIdentifier`.

### Callback Configuration Functions

public void `setVoltageCallbackPeriod`(long period)

  Sets the period in ms with which the `VoltageCallback` callback is triggered periodically. A value of 0 turns the callback off.

  `VoltageCallback` is only triggered if the voltage has changed since the last triggering.

  The default value is 0.

public long `getVoltageCallbackPeriod`()

  Returns the period as set by `setVoltageCallbackPeriod()`.

public void `setAnalogValueCallbackPeriod`(long period)

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

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

  The default value is 0.

public long `getAnalogValueCallbackPeriod`()

  Returns the period as set by `setAnalogValueCallbackPeriod()`.

public void `setVoltageCallbackThreshold`(char option, short min, short max)

  Sets the thresholds for the `VoltageReachedCallback` callback.

  The following options are possible:

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

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

  The following constants are available for this function:

  - BrickletVoltage.THRESHOLD_OPTION_OFF = 'x'
  - BrickletVoltage.THRESHOLD_OPTION_OUTSIDE = 'o'
  - BrickletVoltage.THRESHOLD_OPTION_INSIDE = 'i'
  - BrickletVoltage.THRESHOLD_OPTION_SMALLER = '<'
  - BrickletVoltage.THRESHOLD_OPTION_GREATER = '>'

public BrickletVoltage.VoltageCallbackThreshold `getVoltageCallbackThreshold`()

  Returns the threshold as set by `setVoltageCallbackThreshold()`.

  The following constants are available for this function:

  - BrickletVoltage.THRESHOLD_OPTION_OFF = 'x'
  - BrickletVoltage.THRESHOLD_OPTION_OUTSIDE = 'o'
  - BrickletVoltage.THRESHOLD_OPTION_INSIDE = 'i'
  - BrickletVoltage.THRESHOLD_OPTION_SMALLER = '<'
  - BrickletVoltage.THRESHOLD_OPTION_GREATER = '>'

  The returned object has the public member variables `char option`, `short min` and `short max`.

public void `setAnalogValueCallbackThreshold`(char option, int min, int max)

  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:

  - BrickletVoltage.THRESHOLD_OPTION_OFF = 'x'
  - BrickletVoltage.THRESHOLD_OPTION_OUTSIDE = 'o'
  - BrickletVoltage.THRESHOLD_OPTION_INSIDE = 'i'
  - BrickletVoltage.THRESHOLD_OPTION_SMALLER = '<'
  - BrickletVoltage.THRESHOLD_OPTION_GREATER = '>'

public BrickletVoltage.AnalogValueCallbackThreshold `getAnalogValueCallbackThreshold`()

  Returns the threshold as set by `setAnalogValueCallbackThreshold()`.

  The following constants are available for this function:

  - BrickletVoltage.THRESHOLD_OPTION_OFF = 'x'
  - BrickletVoltage.THRESHOLD_OPTION_OUTSIDE = 'o'
  - BrickletVoltage.THRESHOLD_OPTION_INSIDE = 'i'
  - BrickletVoltage.THRESHOLD_OPTION_SMALLER = '<'
  - BrickletVoltage.THRESHOLD_OPTION_GREATER = '>'

  The returned object has the public member variables `char option`, `int min` and `int max`.

public void `setDebouncePeriod`(long debounce)

  Sets the period in ms with which the threshold callbacks

  - `VoltageReachedCallback`,
  - `AnalogValueReachedCallback`

  are triggered, if the thresholds

  - `setVoltageCallbackThreshold()`,
  - `setAnalogValueCallbackThreshold()`

  keep being reached.

  The default value is 100.

public long `getDebouncePeriod`()

  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 cb_example(e)
        fprintf('Parameter: %s\n', e.param);
    end

    set(device, 'ExampleCallback', @(h, e) cb_example(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 cb_example(e)
        fprintf("Parameter: %s\n", e.param);
    end

    device.addExampleCallback(@cb_example);

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.

public callback `BrickletVoltage.VoltageCallback`

  Parameters: | voltage -- int

  This callback is triggered periodically with the period that is set by `setVoltageCallbackPeriod()`. The parameter is the voltage of the sensor.

  `VoltageCallback` is only triggered if the voltage 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 `addVoltageCallback()` function. An added callback function can be removed with the `removeVoltageCallback()` function.

public callback `BrickletVoltage.AnalogValueCallback`

  Parameters: | value -- int

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

  `AnalogValueCallback` is only triggered if the voltage 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.

public callback `BrickletVoltage.VoltageReachedCallback`

  Parameters: | voltage -- int

  This callback is triggered when the threshold as set by `setVoltageCallbackThreshold()` is reached. The parameter is the voltage 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 `addVoltageReachedCallback()` function. An added callback function can be removed with the `removeVoltageReachedCallback()` function.

public callback `BrickletVoltage.AnalogValueReachedCallback`

  Parameters: | value -- int

  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.

### Constants

public static final int `BrickletVoltage.DEVICE_IDENTIFIER`

  This constant is used to identify a Voltage Bricklet.

  The `getIdentity()` function and the `EnumerateCallback` callback of the IP Connection have a `deviceIdentifier` parameter to specify the Brick's or Bricklet's type.

The content of this page is licensed under Creative Commons Attribution 3.0 Unported License.