MATLAB/Octave - IO-4 Bricklet – Tinkerforge

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# MATLAB/Octave - IO-4 Bricklet

This is the description of the MATLAB/Octave API bindings for the IO-4 Bricklet. General information and technical specifications for the IO-4 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).

### Output (MATLAB)

Download (matlab_example_output.m)

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    function matlab_example_output()
        import com.tinkerforge.IPConnection;
        import com.tinkerforge.BrickletIO4;

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

        ipcon = IPConnection(); % Create IP connection
        io = BrickletIO4(UID, ipcon); % Create device object

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

        % Set pin 1 to output low
        io.setConfiguration(bitshift(1, 1), 'o', false);

        % Set pin 2 and 3 to output high
        io.setConfiguration(bitor(bitshift(1, 2), bitshift(1, 3)), 'o', true);

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

### Interrupt (MATLAB)

Download (matlab_example_interrupt.m)

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    function matlab_example_interrupt()
        import com.tinkerforge.IPConnection;
        import com.tinkerforge.BrickletIO4;

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

        ipcon = IPConnection(); % Create IP connection
        io = BrickletIO4(UID, ipcon); % Create device object

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

        % Register callback for interrupts
        set(io, 'InterruptCallback', @(h, e) cb_interrupt(e));

        % Enable interrupt on pin 0
        io.setInterrupt(bitshift(1, 0));

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

    % Callback function for interrupts
    function cb_interrupt(e)
        fprintf('Interrupt by: %s\n', dec2bin(e.interruptMask));
        fprintf('Value: %s\n', dec2bin(e.valueMask));
    end

### Output (Octave)

Download (octave_example_output.m)

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    function octave_example_output()
        more off;

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

        ipcon = java_new("com.tinkerforge.IPConnection"); % Create IP connection
        io = java_new("com.tinkerforge.BrickletIO4", UID, ipcon); % Create device object

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

        % Set pin 1 to output low
        io.setConfiguration(bitshift(1, 1), "o", true);

        % Set pin 2 and 3 to output high
        io.setConfiguration(bitor(bitshift(1, 2), bitshift(1, 3)), "o", true);

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

### Interrupt (Octave)

Download (octave_example_interrupt.m)

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    function octave_example_interrupt()
        more off;

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

        ipcon = java_new("com.tinkerforge.IPConnection"); % Create IP connection
        io = java_new("com.tinkerforge.BrickletIO4", UID, ipcon); % Create device object

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

        % Register callback for interrupts
        io.addInterruptCallback(@cb_interrupt);

        % Enable interrupt on pin 0
        io.setInterrupt(bitshift(1, 0));

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

    % Callback function for interrupts
    function cb_interrupt(e)
        fprintf("Interrupt by: %s\n", dec2bin(str2num(e.interruptMask.toString())));
        fprintf("Value: %s\n", dec2bin(str2num(e.valueMask.toString())));
    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 `BrickletIO4`(String uid, IPConnection ipcon)

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

  In MATLAB:

      import com.tinkerforge.BrickletIO4;

      io4 = BrickletIO4('YOUR_DEVICE_UID', ipcon);

  In Octave:

      io4 = java_new("com.tinkerforge.BrickletIO4", "YOUR_DEVICE_UID", ipcon);

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

public void `setValue`(short valueMask)

  Sets the output value (high or low) with a bitmask (4bit). A 1 in the bitmask means high and a 0 in the bitmask means low.

  For example: The value 3 or 0b0011 will turn the pins 0-1 high and the pins 2-3 low.

  Note

  This function does nothing for pins that are configured as input. Pull-up resistors can be switched on with `setConfiguration()`.

public short `getValue`()

  Returns a bitmask of the values that are currently measured. This function works if the pin is configured to input as well as if it is configured to output.

public void `setConfiguration`(short selectionMask, char direction, boolean value)

  Configures the value and direction of the specified pins. Possible directions are 'i' and 'o' for input and output.

  If the direction is configured as output, the value is either high or low (set as true or false).

  If the direction is configured as input, the value is either pull-up or default (set as true or false).

  For example:

  - (15, 'i', true) or (0b1111, 'i', true) will set all pins of as input pull-up.
  - (8, 'i', false) or (0b1000, 'i', false) will set pin 3 of as input default (floating if nothing is connected).
  - (3, 'o', false) or (0b0011, 'o', false) will set pins 0 and 1 as output low.
  - (4, 'o', true) or (0b0100, 'o', true) will set pin 2 of as output high.

  The default configuration is input with pull-up.

  The following constants are available for this function:

  - BrickletIO4.DIRECTION_IN = 'i'
  - BrickletIO4.DIRECTION_OUT = 'o'

public BrickletIO4.Configuration `getConfiguration`()

  Returns a value bitmask and a direction bitmask. A 1 in the direction bitmask means input and a 0 in the bitmask means output.

  For example: A return value of (3, 5) or (0b0011, 0b0101) for direction and value means that:

  - pin 0 is configured as input pull-up,
  - pin 1 is configured as input default,
  - pin 2 is configured as output high and
  - pin 3 is are configured as output low.

  The returned object has the public member variables `short directionMask` and `short valueMask`.

public long `getEdgeCount`(short pin, boolean resetCounter)

  Returns the current value of the edge counter for the selected pin. You can configure the edges that are counted with `setEdgeCountConfig()`.

  If you set the reset counter to true, the count is set back to 0 directly after it is read.

  New in version 2.0.1 (Plugin).

### Advanced Functions

public void `setMonoflop`(short selectionMask, short valueMask, long time)

  Configures a monoflop of the pins specified by the first parameter as 4 bit long bitmask. The specified pins must be configured for output. Non-output pins will be ignored.

  The second parameter is a bitmask with the desired value of the specified output pins. A 1 in the bitmask means high and a 0 in the bitmask means low.

  The third parameter indicates the time (in ms) that the pins should hold the value.

  If this function is called with the parameters (9, 1, 1500) or (0b1001, 0b0001, 1500): Pin 0 will get high and pin 3 will get low. In 1.5s pin 0 will get low and pin 3 will get high again.

  A monoflop can be used as a fail-safe mechanism. For example: Lets assume you have a RS485 bus and an IO-4 Bricklet connected to one of the slave stacks. You can now call this function every second, with a time parameter of two seconds and pin 0 set to high. Pin 0 will be high all the time. If now the RS485 connection is lost, then pin 0 will get low in at most two seconds.

public BrickletIO4.Monoflop `getMonoflop`(short pin)

  Returns (for the given pin) the current value and the time as set by `setMonoflop()` as well as the remaining time until the value flips.

  If the timer is not running currently, the remaining time will be returned as 0.

  The returned object has the public member variables `short value`, `long time` and `long timeRemaining`.

public void `setSelectedValues`(short selectionMask, short valueMask)

  Sets the output value (high or low) with a bitmask, according to the selection mask. The bitmask is 4 bit long, true refers to high and false refers to low.

  For example: The parameters (9, 4) or (0b0110, 0b0100) will turn pin 1 low and pin 2 high, pin 0 and 3 will remain untouched.

  Note

  This function does nothing for pins that are configured as input. Pull-up resistors can be switched on with `setConfiguration()`.

public void `setEdgeCountConfig`(short selectionMask, short edgeType, short debounce)

  Configures the edge counter for the selected pins.

  The edge type parameter configures if rising edges, falling edges or both are counted if the pin is configured for input. Possible edge types are:

  - 0 = rising (default)
  - 1 = falling
  - 2 = both

  The debounce time is given in ms.

  Configuring an edge counter resets its value to 0.

  If you don't know what any of this means, just leave it at default. The default configuration is very likely OK for you.

  Default values: 0 (edge type) and 100ms (debounce time)

  The following constants are available for this function:

  - BrickletIO4.EDGE_TYPE_RISING = 0
  - BrickletIO4.EDGE_TYPE_FALLING = 1
  - BrickletIO4.EDGE_TYPE_BOTH = 2

  New in version 2.0.1 (Plugin).

public BrickletIO4.EdgeCountConfig `getEdgeCountConfig`(short pin)

  Returns the edge type and debounce time for the selected pin as set by `setEdgeCountConfig()`.

  The following constants are available for this function:

  - BrickletIO4.EDGE_TYPE_RISING = 0
  - BrickletIO4.EDGE_TYPE_FALLING = 1
  - BrickletIO4.EDGE_TYPE_BOTH = 2

  New in version 2.0.1 (Plugin).

  The returned object has the public member variables `short edgeType` and `short debounce`.

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:

  - BrickletIO4.FUNCTION_SET_VALUE = 1
  - BrickletIO4.FUNCTION_SET_CONFIGURATION = 3
  - BrickletIO4.FUNCTION_SET_DEBOUNCE_PERIOD = 5
  - BrickletIO4.FUNCTION_SET_INTERRUPT = 7
  - BrickletIO4.FUNCTION_SET_MONOFLOP = 10
  - BrickletIO4.FUNCTION_SET_SELECTED_VALUES = 13
  - BrickletIO4.FUNCTION_SET_EDGE_COUNT_CONFIG = 15

public void `setResponseExpectedAll`(boolean responseExpected)

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

public BrickletIO4.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 `setDebouncePeriod`(long debounce)

  Sets the debounce period of the `InterruptCallback` callback in ms.

  For example: If you set this value to 100, you will get the interrupt maximal every 100ms. This is necessary if something that bounces is connected to the IO-4 Bricklet, such as a button.

  The default value is 100.

public long `getDebouncePeriod`()

  Returns the debounce period as set by `setDebouncePeriod()`.

public void `setInterrupt`(short interruptMask)

  Sets the pins on which an interrupt is activated with a bitmask. Interrupts are triggered on changes of the voltage level of the pin, i.e. changes from high to low and low to high.

  For example: An interrupt bitmask of 10 or 0b1010 will enable the interrupt for pins 1 and 3.

  The interrupt is delivered with the callback `InterruptCallback`.

public short `getInterrupt`()

  Returns the interrupt bitmask as set by `setInterrupt()`.

### 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 `BrickletIO4.InterruptCallback`

  Parameters:

  - interruptMask -- short
  - valueMask -- short

  This callback is triggered whenever a change of the voltage level is detected on pins where the interrupt was activated with `setInterrupt()`.

  The values are a bitmask that specifies which interrupts occurred and the current value bitmask.

  For example:

  - (1, 1) or (0b0001, 0b0001) means that an interrupt on pin 0 occurred and currently pin 0 is high and pins 1-3 are low.
  - (9, 14) or (0b1001, 0b1110) means that interrupts on pins 0 and 3 occurred and currently pin 0 is low and pins 1-3 are high.

  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 `addInterruptCallback()` function. An added callback function can be removed with the `removeInterruptCallback()` function.

public callback `BrickletIO4.MonoflopDoneCallback`

  Parameters:

  - selectionMask -- short
  - valueMask -- short

  This callback is triggered whenever a monoflop timer reaches 0. The parameters contain the involved pins and the current value of the pins (the value after the monoflop).

  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 `addMonoflopDoneCallback()` function. An added callback function can be removed with the `removeMonoflopDoneCallback()` function.

### Constants

public static final int `BrickletIO4.DEVICE_IDENTIFIER`

  This constant is used to identify a IO-4 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.

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