MATLAB/Octave - RS232 Bricklet 2.0

This is the description of the MATLAB/Octave API bindings for the RS232 Bricklet 2.0. General information and technical specifications for the RS232 Bricklet 2.0 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).

Loopback (MATLAB)

Download (matlab_example_loopback.m)

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function matlab_example_loopback()
    import com.tinkerforge.IPConnection;
    import com.tinkerforge.BrickletRS232V2;
    import java.lang.String;

    % For this example connect the RX1 and TX pin to receive the send message

    HOST = 'localhost';
    PORT = 4223;
    UID = 'XYZ'; % Change XYZ to the UID of your RS232 Bricklet 2.0

    ipcon = IPConnection(); % Create IP connection
    rs232 = handle(BrickletRS232V2(UID, ipcon), 'CallbackProperties'); % Create device object

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

    % Register read callback to function cb_read
    set(rs232, 'ReadCallback', @(h, e) cb_read(e));

    % Enable read callback
    rs232.enableReadCallback();

    % Write "test" string
    rs232.write(String('test').toCharArray());

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

% Callback function for read callback
function cb_read(e)
    fprintf('Message: %s\n', e.message);
end

Loopback (Octave)

Download (octave_example_loopback.m)

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function octave_example_loopback()
    more off;

    % For this example connect the RX1 and TX pin to receive the send message

    HOST = "localhost";
    PORT = 4223;
    UID = "XYZ"; % Change XYZ to the UID of your RS232 Bricklet 2.0

    ipcon = javaObject("com.tinkerforge.IPConnection"); % Create IP connection
    rs232 = javaObject("com.tinkerforge.BrickletRS232V2", UID, ipcon); % Create device object

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

    % Register read callback to function cb_read
    rs232.addReadCallback(@cb_read);

    % Enable read callback
    rs232.enableReadCallback();

    % Write "test" string
    rs232.write(string2chars("test")); % FIXME: throws java.lang.StringIndexOutOfBoundsException: String index out of range: 0

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

% Callback function for read callback
function cb_read(e)
    fprintf("Message: \"%s\"\n", chars2string(e.message));
end

% Convert string to array
function chars = string2chars(string)
    chars = javaArray("java.lang.String", length(string));

    for i = 1:length(string)
        chars(i) = substr(string, i, 1);
    end
end

% Assume that the message consists of ASCII characters and
% convert it from an array of chars to a string
function string = chars2string(chars)
    string = "";

    for i = 1:length(chars)
        string = strcat(string, chars(i));
    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 BrickletRS232V2(String uid, IPConnection ipcon)
Parameters:
  • uid – Type: String
  • ipcon – Type: IPConnection
Returns:
  • rs232V2 – Type: BrickletRS232V2

Creates an object with the unique device ID uid.

In MATLAB:

import com.tinkerforge.BrickletRS232V2;

rs232V2 = BrickletRS232V2('YOUR_DEVICE_UID', ipcon);

In Octave:

rs232V2 = java_new("com.tinkerforge.BrickletRS232V2", "YOUR_DEVICE_UID", ipcon);

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

int BrickletRS232V2.write(char[] message)
Parameters:
  • message – Type: char[], Length: variable
Returns:
  • messageWritten – Type: int, Range: [0 to 216 - 1]

Writes characters to the RS232 interface. The characters can be binary data, ASCII or similar is not necessary.

The return value is the number of characters that were written.

See setConfiguration() for configuration possibilities regarding baud rate, parity and so on.

char[] BrickletRS232V2.read(int length)
Parameters:
  • length – Type: int, Range: [0 to 216 - 1]
Returns:
  • message – Type: char[], Length: variable

Returns up to length characters from receive buffer.

Instead of polling with this function, you can also use callbacks. But note that this function will return available data only when the read callback is disabled. See enableReadCallback() and ReadCallback callback.

void BrickletRS232V2.setConfiguration(long baudrate, int parity, int stopbits, int wordlength, int flowcontrol)
Parameters:
  • baudrate – Type: long, Unit: 1 Bd, Range: [100 to 2000000], Default: 115200
  • parity – Type: int, Range: See constants, Default: 0
  • stopbits – Type: int, Range: See constants, Default: 1
  • wordlength – Type: int, Range: See constants, Default: 8
  • flowcontrol – Type: int, Range: See constants, Default: 0

Sets the configuration for the RS232 communication.

The following constants are available for this function:

For parity:

  • BrickletRS232V2.PARITY_NONE = 0
  • BrickletRS232V2.PARITY_ODD = 1
  • BrickletRS232V2.PARITY_EVEN = 2

For stopbits:

  • BrickletRS232V2.STOPBITS_1 = 1
  • BrickletRS232V2.STOPBITS_2 = 2

For wordlength:

  • BrickletRS232V2.WORDLENGTH_5 = 5
  • BrickletRS232V2.WORDLENGTH_6 = 6
  • BrickletRS232V2.WORDLENGTH_7 = 7
  • BrickletRS232V2.WORDLENGTH_8 = 8

For flowcontrol:

  • BrickletRS232V2.FLOWCONTROL_OFF = 0
  • BrickletRS232V2.FLOWCONTROL_SOFTWARE = 1
  • BrickletRS232V2.FLOWCONTROL_HARDWARE = 2
BrickletRS232V2.Configuration BrickletRS232V2.getConfiguration()
Return Object:
  • baudrate – Type: long, Unit: 1 Bd, Range: [100 to 2000000], Default: 115200
  • parity – Type: int, Range: See constants, Default: 0
  • stopbits – Type: int, Range: See constants, Default: 1
  • wordlength – Type: int, Range: See constants, Default: 8
  • flowcontrol – Type: int, Range: See constants, Default: 0

Returns the configuration as set by setConfiguration().

The following constants are available for this function:

For parity:

  • BrickletRS232V2.PARITY_NONE = 0
  • BrickletRS232V2.PARITY_ODD = 1
  • BrickletRS232V2.PARITY_EVEN = 2

For stopbits:

  • BrickletRS232V2.STOPBITS_1 = 1
  • BrickletRS232V2.STOPBITS_2 = 2

For wordlength:

  • BrickletRS232V2.WORDLENGTH_5 = 5
  • BrickletRS232V2.WORDLENGTH_6 = 6
  • BrickletRS232V2.WORDLENGTH_7 = 7
  • BrickletRS232V2.WORDLENGTH_8 = 8

For flowcontrol:

  • BrickletRS232V2.FLOWCONTROL_OFF = 0
  • BrickletRS232V2.FLOWCONTROL_SOFTWARE = 1
  • BrickletRS232V2.FLOWCONTROL_HARDWARE = 2

Advanced Functions

void BrickletRS232V2.setBufferConfig(int sendBufferSize, int receiveBufferSize)
Parameters:
  • sendBufferSize – Type: int, Unit: 1 B, Range: [1024 to 9216], Default: 5120
  • receiveBufferSize – Type: int, Unit: 1 B, Range: [1024 to 9216], Default: 5120

Sets the send and receive buffer size in byte. In total the buffers have to be 10240 byte (10KiB) in size, the minimum buffer size is 1024 byte (1KiB) for each.

The current buffer content is lost if this function is called.

The send buffer holds data that is given by write() and can not be written yet. The receive buffer holds data that is received through RS232 but could not yet be send to the user, either by read() or through ReadCallback callback.

BrickletRS232V2.BufferConfig BrickletRS232V2.getBufferConfig()
Return Object:
  • sendBufferSize – Type: int, Unit: 1 B, Range: [1024 to 9216], Default: 5120
  • receiveBufferSize – Type: int, Unit: 1 B, Range: [1024 to 9216], Default: 5120

Returns the buffer configuration as set by setBufferConfig().

BrickletRS232V2.BufferStatus BrickletRS232V2.getBufferStatus()
Return Object:
  • sendBufferUsed – Type: int, Unit: 1 B, Range: [1024 to 9216]
  • receiveBufferUsed – Type: int, Unit: 1 B, Range: [1024 to 9216]

Returns the currently used bytes for the send and received buffer.

See setBufferConfig() for buffer size configuration.

BrickletRS232V2.ErrorCount BrickletRS232V2.getErrorCount()
Return Object:
  • errorCountOverrun – Type: long, Range: [0 to 232 - 1]
  • errorCountParity – Type: long, Range: [0 to 232 - 1]

Returns the current number of overrun and parity errors.

BrickletRS232V2.SPITFPErrorCount BrickletRS232V2.getSPITFPErrorCount()
Return Object:
  • errorCountAckChecksum – Type: long, Range: [0 to 232 - 1]
  • errorCountMessageChecksum – Type: long, Range: [0 to 232 - 1]
  • errorCountFrame – Type: long, Range: [0 to 232 - 1]
  • errorCountOverflow – Type: long, Range: [0 to 232 - 1]

Returns the error count for the communication between Brick and Bricklet.

The errors are divided into

  • ACK checksum errors,
  • message checksum errors,
  • framing errors and
  • overflow errors.

The errors counts are for errors that occur on the Bricklet side. All Bricks have a similar function that returns the errors on the Brick side.

int BrickletRS232V2.setBootloaderMode(int mode)
Parameters:
  • mode – Type: int, Range: See constants
Returns:
  • status – Type: int, Range: See constants

Sets the bootloader mode and returns the status after the requested mode change was instigated.

You can change from bootloader mode to firmware mode and vice versa. A change from bootloader mode to firmware mode will only take place if the entry function, device identifier and CRC are present and correct.

This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.

The following constants are available for this function:

For mode:

  • BrickletRS232V2.BOOTLOADER_MODE_BOOTLOADER = 0
  • BrickletRS232V2.BOOTLOADER_MODE_FIRMWARE = 1
  • BrickletRS232V2.BOOTLOADER_MODE_BOOTLOADER_WAIT_FOR_REBOOT = 2
  • BrickletRS232V2.BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_REBOOT = 3
  • BrickletRS232V2.BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_ERASE_AND_REBOOT = 4

For status:

  • BrickletRS232V2.BOOTLOADER_STATUS_OK = 0
  • BrickletRS232V2.BOOTLOADER_STATUS_INVALID_MODE = 1
  • BrickletRS232V2.BOOTLOADER_STATUS_NO_CHANGE = 2
  • BrickletRS232V2.BOOTLOADER_STATUS_ENTRY_FUNCTION_NOT_PRESENT = 3
  • BrickletRS232V2.BOOTLOADER_STATUS_DEVICE_IDENTIFIER_INCORRECT = 4
  • BrickletRS232V2.BOOTLOADER_STATUS_CRC_MISMATCH = 5
int BrickletRS232V2.getBootloaderMode()
Returns:
  • mode – Type: int, Range: See constants

Returns the current bootloader mode, see setBootloaderMode().

The following constants are available for this function:

For mode:

  • BrickletRS232V2.BOOTLOADER_MODE_BOOTLOADER = 0
  • BrickletRS232V2.BOOTLOADER_MODE_FIRMWARE = 1
  • BrickletRS232V2.BOOTLOADER_MODE_BOOTLOADER_WAIT_FOR_REBOOT = 2
  • BrickletRS232V2.BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_REBOOT = 3
  • BrickletRS232V2.BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_ERASE_AND_REBOOT = 4
void BrickletRS232V2.setWriteFirmwarePointer(long pointer)
Parameters:
  • pointer – Type: long, Unit: 1 B, Range: [0 to 232 - 1]

Sets the firmware pointer for writeFirmware(). The pointer has to be increased by chunks of size 64. The data is written to flash every 4 chunks (which equals to one page of size 256).

This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.

int BrickletRS232V2.writeFirmware(int[] data)
Parameters:
  • data – Type: int[], Length: 64, Range: [0 to 255]
Returns:
  • status – Type: int, Range: [0 to 255]

Writes 64 Bytes of firmware at the position as written by setWriteFirmwarePointer() before. The firmware is written to flash every 4 chunks.

You can only write firmware in bootloader mode.

This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.

void BrickletRS232V2.setStatusLEDConfig(int config)
Parameters:
  • config – Type: int, Range: See constants, Default: 3

Sets the status LED configuration. By default the LED shows communication traffic between Brick and Bricklet, it flickers once for every 10 received data packets.

You can also turn the LED permanently on/off or show a heartbeat.

If the Bricklet is in bootloader mode, the LED is will show heartbeat by default.

The following constants are available for this function:

For config:

  • BrickletRS232V2.STATUS_LED_CONFIG_OFF = 0
  • BrickletRS232V2.STATUS_LED_CONFIG_ON = 1
  • BrickletRS232V2.STATUS_LED_CONFIG_SHOW_HEARTBEAT = 2
  • BrickletRS232V2.STATUS_LED_CONFIG_SHOW_STATUS = 3
int BrickletRS232V2.getStatusLEDConfig()
Returns:
  • config – Type: int, Range: See constants, Default: 3

Returns the configuration as set by setStatusLEDConfig()

The following constants are available for this function:

For config:

  • BrickletRS232V2.STATUS_LED_CONFIG_OFF = 0
  • BrickletRS232V2.STATUS_LED_CONFIG_ON = 1
  • BrickletRS232V2.STATUS_LED_CONFIG_SHOW_HEARTBEAT = 2
  • BrickletRS232V2.STATUS_LED_CONFIG_SHOW_STATUS = 3
int BrickletRS232V2.getChipTemperature()
Returns:
  • temperature – Type: int, Unit: 1 °C, Range: [-215 to 215 - 1]

Returns the temperature as measured inside the microcontroller. The value returned is not the ambient temperature!

The temperature is only proportional to the real temperature and it has bad accuracy. Practically it is only useful as an indicator for temperature changes.

void BrickletRS232V2.reset()

Calling this function will reset the Bricklet. All configurations will be lost.

After a reset you have to create new device objects, calling functions on the existing ones will result in undefined behavior!

void BrickletRS232V2.writeUID(long uid)
Parameters:
  • uid – Type: long, Range: [0 to 232 - 1]

Writes a new UID into flash. If you want to set a new UID you have to decode the Base58 encoded UID string into an integer first.

We recommend that you use Brick Viewer to change the UID.

long BrickletRS232V2.readUID()
Returns:
  • uid – Type: long, Range: [0 to 232 - 1]

Returns the current UID as an integer. Encode as Base58 to get the usual string version.

BrickletRS232V2.Identity BrickletRS232V2.getIdentity()
Return Object:
  • uid – Type: String, Length: up to 8
  • connectedUid – Type: String, Length: up to 8
  • position – Type: char, Range: ['a' to 'h', 'i', 'z']
  • hardwareVersion – Type: int[], Length: 3
    • 1: major – Type: int, Range: [0 to 255]
    • 2: minor – Type: int, Range: [0 to 255]
    • 3: revision – Type: int, Range: [0 to 255]
  • firmwareVersion – Type: int[], Length: 3
    • 1: major – Type: int, Range: [0 to 255]
    • 2: minor – Type: int, Range: [0 to 255]
    • 3: revision – Type: int, 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). The Raspberry Pi HAT (Zero) Brick is always at position 'i' and the Bricklet connected to an Isolator Bricklet is always as 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 BrickletRS232V2.enableReadCallback()

Enables the ReadCallback callback.

By default the callback is disabled.

void BrickletRS232V2.disableReadCallback()

Disables the ReadCallback callback.

By default the callback is disabled.

boolean BrickletRS232V2.isReadCallbackEnabled()
Returns:
  • enabled – Type: boolean, Default: false

Returns true if the ReadCallback callback is enabled, false otherwise.

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 BrickletRS232V2.ReadCallback
Event Object:
  • message – Type: char[], Length: variable

This callback is called if new data is available.

To enable this callback, use enableReadCallback().

Note

If reconstructing the value fails, the callback is triggered with null for message.

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 addReadCallback() function. An added callback function can be removed with the removeReadCallback() function.

callback BrickletRS232V2.ErrorCountCallback
Event Object:
  • errorCountOverrun – Type: long, Range: [0 to 232 - 1]
  • errorCountParity – Type: long, Range: [0 to 232 - 1]

This callback is called if a new error occurs. It returns the current overrun and parity error count.

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 addErrorCountCallback() function. An added callback function can be removed with the removeErrorCountCallback() 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.

int[] BrickletRS232V2.getAPIVersion()
Return Object:
  • apiVersion – Type: int[], Length: 3
    • 1: major – Type: int, Range: [0 to 255]
    • 2: minor – Type: int, Range: [0 to 255]
    • 3: revision – Type: int, 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 BrickletRS232V2.getResponseExpected(int functionId)
Parameters:
  • functionId – Type: int, 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:

  • BrickletRS232V2.FUNCTION_ENABLE_READ_CALLBACK = 3
  • BrickletRS232V2.FUNCTION_DISABLE_READ_CALLBACK = 4
  • BrickletRS232V2.FUNCTION_SET_CONFIGURATION = 6
  • BrickletRS232V2.FUNCTION_SET_BUFFER_CONFIG = 8
  • BrickletRS232V2.FUNCTION_SET_WRITE_FIRMWARE_POINTER = 237
  • BrickletRS232V2.FUNCTION_SET_STATUS_LED_CONFIG = 239
  • BrickletRS232V2.FUNCTION_RESET = 243
  • BrickletRS232V2.FUNCTION_WRITE_UID = 248
void BrickletRS232V2.setResponseExpected(int functionId, boolean responseExpected)
Parameters:
  • functionId – Type: int, 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:

  • BrickletRS232V2.FUNCTION_ENABLE_READ_CALLBACK = 3
  • BrickletRS232V2.FUNCTION_DISABLE_READ_CALLBACK = 4
  • BrickletRS232V2.FUNCTION_SET_CONFIGURATION = 6
  • BrickletRS232V2.FUNCTION_SET_BUFFER_CONFIG = 8
  • BrickletRS232V2.FUNCTION_SET_WRITE_FIRMWARE_POINTER = 237
  • BrickletRS232V2.FUNCTION_SET_STATUS_LED_CONFIG = 239
  • BrickletRS232V2.FUNCTION_RESET = 243
  • BrickletRS232V2.FUNCTION_WRITE_UID = 248
void BrickletRS232V2.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 BrickletRS232V2.DEVICE_IDENTIFIER

This constant is used to identify a RS232 Bricklet 2.0.

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 BrickletRS232V2.DEVICE_DISPLAY_NAME

This constant represents the human readable name of a RS232 Bricklet 2.0.