C/C++ - RS232 Bricklet – Tinkerforge

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# C/C++ - RS232 Bricklet

Note

This Bricklet is currently in the prototype stage and the software/hardware as well as the documentation is in an incomplete state.

This is the description of the C/C++ API bindings for the RS232 Bricklet. General information and technical specifications for the RS232 Bricklet are summarized in its hardware description.

An installation guide for the C/C++ API bindings is part of their general description.

## Examples

The example code below is Public Domain (CC0 1.0).

## API

Every function of the C/C++ bindings returns an integer which describes an error code. Data returned from the device, when a getter is called, is handled via call by reference. These parameters are labeled with the `ret_` prefix.

Possible error codes are:

- E_OK = 0
- E_TIMEOUT = -1
- E_NO_STREAM_SOCKET = -2
- E_HOSTNAME_INVALID = -3
- E_NO_CONNECT = -4
- E_NO_THREAD = -5
- E_NOT_ADDED = -6 (unused since bindings version 2.0.0)
- E_ALREADY_CONNECTED = -7
- E_NOT_CONNECTED = -8
- E_INVALID_PARAMETER = -9
- E_NOT_SUPPORTED = -10
- E_UNKNOWN_ERROR_CODE = -11

as defined in `ip_connection.h`.

All functions listed below are thread-safe.

### Basic Functions

void `rs232_create`(RS232 *rs232, const char *uid, IPConnection *ipcon)

  Creates the device object `rs232` with the unique device ID `uid` and adds it to the IPConnection `ipcon`:

      RS232 rs232;
      rs232_create(&rs232, "YOUR_DEVICE_UID", &ipcon);

  This device object can be used after the IP connection has been connected (see examples above).

void `rs232_destroy`(RS232 *rs232)

  Removes the device object `rs232` from its IPConnection and destroys it. The device object cannot be used anymore afterwards.

int `rs232_write`(RS232 *rs232, char message[60], uint8_t length, uint8_t *ret_written)

  Writes a string of up to 60 characters to the RS232 interface. The string can be binary data, ASCII or similar is not necessary.

  The length of the string has to be given as an additional parameter.

  The return value is the number of bytes that could be written.

  See `SetConfigurations()` for configuration possibilities regarding baudrate, parity and so on.

int `rs232_read`(RS232 *rs232, char ret_message[60], uint8_t *ret_length)

  Returns the currently buffered message. The maximum length of message is 60. If the length is given as 0, there was no new data available.

  Instead of polling with this function, you can also use callbacks. See `rs232_enable_callback()` and `RS232_CALLBACK_READ_CALLBACK`.

int `rs232_set_configuration`(RS232 *rs232, uint8_t baudrate, uint8_t parity, uint8_t stopbits, uint8_t wordlength, uint8_t hardware_flowcontrol, uint8_t software_flowcontrol)

  Sets the configuration for the RS232 communication. Available options:

  - Baudrate between 300 and 230400 baud.
  - Parity of none, odd, even or forced parity.
  - Stopbits can be 1 or 2.
  - Word length of 5 to 8.
  - Hard-/Software flow control can each be on or off.

  The default is: 115200 baud, parity none, 1 stop bit, word length 8, hard-/software flow control off.

  The following defines are available for this function:

  - RS232_BAUDRATE_300 = 0
  - RS232_BAUDRATE_600 = 1
  - RS232_BAUDRATE_1200 = 2
  - RS232_BAUDRATE_2400 = 3
  - RS232_BAUDRATE_4800 = 4
  - RS232_BAUDRATE_9600 = 5
  - RS232_BAUDRATE_14400 = 6
  - RS232_BAUDRATE_28800 = 7
  - RS232_BAUDRATE_38400 = 8
  - RS232_BAUDRATE_57600 = 9
  - RS232_BAUDRATE_115200 = 10
  - RS232_BAUDRATE_230400 = 11
  - RS232_PARITY_NONE = 0
  - RS232_PARITY_ODD = 1
  - RS232_PARITY_EVEN = 2
  - RS232_PARITY_FORCED_PARITY_1 = 3
  - RS232_PARITY_FORCED_PARITY_0 = 4
  - RS232_STOPBITS_1 = 1
  - RS232_STOPBITS_2 = 2
  - RS232_WORDLENGTH_5 = 5
  - RS232_WORDLENGTH_6 = 6
  - RS232_WORDLENGTH_7 = 7
  - RS232_WORDLENGTH_8 = 8
  - RS232_HARDWARE_FLOWCONTROL_OFF = 0
  - RS232_HARDWARE_FLOWCONTROL_ON = 1
  - RS232_SOFTWARE_FLOWCONTROL_OFF = 0
  - RS232_SOFTWARE_FLOWCONTROL_ON = 1

int `rs232_get_configuration`(RS232 *rs232, uint8_t *ret_baudrate, uint8_t *ret_parity, uint8_t *ret_stopbits, uint8_t *ret_wordlength, uint8_t *ret_hardware_flowcontrol, uint8_t *ret_software_flowcontrol)

  Returns the configuration as set by `rs232_set_configuration()`.

  The following defines are available for this function:

  - RS232_BAUDRATE_300 = 0
  - RS232_BAUDRATE_600 = 1
  - RS232_BAUDRATE_1200 = 2
  - RS232_BAUDRATE_2400 = 3
  - RS232_BAUDRATE_4800 = 4
  - RS232_BAUDRATE_9600 = 5
  - RS232_BAUDRATE_14400 = 6
  - RS232_BAUDRATE_28800 = 7
  - RS232_BAUDRATE_38400 = 8
  - RS232_BAUDRATE_57600 = 9
  - RS232_BAUDRATE_115200 = 10
  - RS232_BAUDRATE_230400 = 11
  - RS232_PARITY_NONE = 0
  - RS232_PARITY_ODD = 1
  - RS232_PARITY_EVEN = 2
  - RS232_PARITY_FORCED_PARITY_1 = 3
  - RS232_PARITY_FORCED_PARITY_0 = 4
  - RS232_STOPBITS_1 = 1
  - RS232_STOPBITS_2 = 2
  - RS232_WORDLENGTH_5 = 5
  - RS232_WORDLENGTH_6 = 6
  - RS232_WORDLENGTH_7 = 7
  - RS232_WORDLENGTH_8 = 8
  - RS232_HARDWARE_FLOWCONTROL_OFF = 0
  - RS232_HARDWARE_FLOWCONTROL_ON = 1
  - RS232_SOFTWARE_FLOWCONTROL_OFF = 0
  - RS232_SOFTWARE_FLOWCONTROL_ON = 1

### Advanced Functions

int `rs232_get_api_version`(RS232 *rs232, uint8_t ret_api_version[3])

  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.

int `rs232_get_response_expected`(RS232 *rs232, uint8_t function_id, bool *ret_response_expected)

  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 `rs232_set_response_expected()`. 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 `rs232_set_response_expected()` for the list of function ID defines available for this function.

int `rs232_set_response_expected`(RS232 *rs232, uint8_t function_id, bool response_expected)

  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 defines are available for this function:

  - RS232_FUNCTION_ENABLE_CALLBACK = 3
  - RS232_FUNCTION_DISABLE_CALLBACK = 4
  - RS232_FUNCTION_SET_CONFIGURATION = 6

int `rs232_set_response_expected_all`(RS232 *rs232, bool response_expected)

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

int `rs232_get_identity`(RS232 *rs232, char ret_uid[8], char ret_connected_uid[8], char *ret_position, uint8_t ret_hardware_version[3], uint8_t ret_firmware_version[3], uint16_t *ret_device_identifier)

  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 `rs232_register_callback`(RS232 *rs232, uint8_t id, void *callback, void *user_data)

  Registers a callback with ID `id` to the function `callback`. The `user_data` will be given as a parameter of the callback.

  The available IDs with corresponding function signatures are listed below.

int `rs232_enable_callback`(RS232 *rs232)

  Enables the `RS232_CALLBACK_READ_CALLBACK`.

  By default the callback is disabled.

int `rs232_disable_callback`(RS232 *rs232)

  Disables the `RS232_CALLBACK_READ_CALLBACK`.

  By default the callback is disabled.

int `rs232_is_callback_enabled`(RS232 *rs232, bool *ret_enable)

  Returns true if the `RS232_CALLBACK_READ_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 the `rs232_register_callback()` function. The parameters consist of the device object, the callback ID, the callback function and optional user data:

>     void my_callback(int p, void *user_data) {
>         printf("parameter: %d\n", p);
>     }

>     rs232_register_callback(&rs232, RS232_CALLBACK_EXAMPLE, (void *)my_callback, NULL);

The available constants with corresponding callback function signatures 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.

`RS232_CALLBACK_READ_CALLBACK`

      void callback(char message[60], uint8_t length, void *user_data)

  This callback is called if new data is available. The message has a maximum size of 60 characters. The actual length of the message is given in addition.

  To enable this callback, use `rs232_enable_callback()`.

### Constants

`RS232_DEVICE_IDENTIFIER`

  This constant is used to identify a RS232 Bricklet.

  The `rs232_get_identity()` function and the `IPCON_CALLBACK_ENUMERATE` callback of the IP Connection have a `device_identifier` parameter to specify the Brick's or Bricklet's type.

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