C/C++ - RS232 Bricklet 2.0

This is the description of the C/C++ 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 C/C++ API bindings is part of their general description.

Examples

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

Loopback

Download (example_loopback.c)

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
#include <stdio.h>
#include <stdlib.h>

// For this example connect the RX pin to the TX pin on the same Bricklet

#include "ip_connection.h"
#include "bricklet_rs232_v2.h"

#define HOST "localhost"
#define PORT 4223
#define UID "XYZ" // Change XYZ to the UID of your RS232 Bricklet 2.0

// Callback function for read callback
void cb_read(char *message, uint16_t message_length, void *user_data) {
    (void)user_data; // avoid unused parameter warning

    // Assume that the message consists of ASCII characters and
    // convert it from an array of chars to a NUL-terminated string
    char *buffer = (char *)malloc(message_length + 1); // +1 for the NUL-terminator
    memcpy(buffer, message, message_length);
    buffer[message_length] = '\0';

    printf("Message: \"%s\"\n", buffer);

    free(buffer);
}

int main(void) {
    // Create IP connection
    IPConnection ipcon;
    ipcon_create(&ipcon);

    // Create device object
    RS232V2 rs232;
    rs232_v2_create(&rs232, UID, &ipcon);

    // Connect to brickd
    if(ipcon_connect(&ipcon, HOST, PORT) < 0) {
        fprintf(stderr, "Could not connect\n");
        return 1;
    }
    // Don't use device before ipcon is connected

    // Register read callback to function cb_read
    rs232_v2_register_callback(&rs232,
                               RS232_V2_CALLBACK_READ,
                               (void *)cb_read,
                               NULL);

    // Enable read callback
    rs232_v2_enable_read_callback(&rs232);

    // Write "test" string
    const char *message = "test";
    uint16_t written;
    rs232_v2_write(&rs232, message, strlen(message), &written);

    printf("Press key to exit\n");
    getchar();
    rs232_v2_destroy(&rs232);
    ipcon_destroy(&ipcon); // Calls ipcon_disconnect internally
    return 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
  • E_STREAM_OUT_OF_SYNC = -12

as defined in ip_connection.h.

All functions listed below are thread-safe.

Basic Functions

void rs232_v2_create(RS232V2 *rs232_v2, const char *uid, IPConnection *ipcon)

Creates the device object rs232_v2 with the unique device ID uid and adds it to the IPConnection ipcon:

RS232V2 rs232_v2;
rs232_v2_create(&rs232_v2, "YOUR_DEVICE_UID", &ipcon);

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

void rs232_v2_destroy(RS232V2 *rs232_v2)

Removes the device object rs232_v2 from its IPConnection and destroys it. The device object cannot be used anymore afterwards.

int rs232_v2_write(RS232V2 *rs232_v2, const char *message, uint16_t message_length, uint16_t *ret_message_written)

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 rs232_v2_set_configuration() for configuration possibilities regarding baud rate, parity and so on.

int rs232_v2_read(RS232V2 *rs232_v2, uint16_t length, char *ret_message, uint16_t *ret_message_length)

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 rs232_v2_enable_read_callback() and RS232_V2_CALLBACK_READ callback.

int rs232_v2_set_configuration(RS232V2 *rs232_v2, uint32_t baudrate, uint8_t parity, uint8_t stopbits, uint8_t wordlength, uint8_t flowcontrol)

Sets the configuration for the RS232 communication. Available options:

  • Baud rate between 100 and 2000000 baud.
  • Parity of none, odd or even.
  • Stop bits can be 1 or 2.
  • Word length of 5 to 8.
  • Flow control can be off, software or hardware.

The default is: 115200 baud, parity none, 1 stop bit, word length 8.

The following defines are available for this function:

  • RS232_V2_PARITY_NONE = 0
  • RS232_V2_PARITY_ODD = 1
  • RS232_V2_PARITY_EVEN = 2
  • RS232_V2_STOPBITS_1 = 1
  • RS232_V2_STOPBITS_2 = 2
  • RS232_V2_WORDLENGTH_5 = 5
  • RS232_V2_WORDLENGTH_6 = 6
  • RS232_V2_WORDLENGTH_7 = 7
  • RS232_V2_WORDLENGTH_8 = 8
  • RS232_V2_FLOWCONTROL_OFF = 0
  • RS232_V2_FLOWCONTROL_SOFTWARE = 1
  • RS232_V2_FLOWCONTROL_HARDWARE = 2
int rs232_v2_get_configuration(RS232V2 *rs232_v2, uint32_t *ret_baudrate, uint8_t *ret_parity, uint8_t *ret_stopbits, uint8_t *ret_wordlength, uint8_t *ret_flowcontrol)

Returns the configuration as set by rs232_v2_set_configuration().

The following defines are available for this function:

  • RS232_V2_PARITY_NONE = 0
  • RS232_V2_PARITY_ODD = 1
  • RS232_V2_PARITY_EVEN = 2
  • RS232_V2_STOPBITS_1 = 1
  • RS232_V2_STOPBITS_2 = 2
  • RS232_V2_WORDLENGTH_5 = 5
  • RS232_V2_WORDLENGTH_6 = 6
  • RS232_V2_WORDLENGTH_7 = 7
  • RS232_V2_WORDLENGTH_8 = 8
  • RS232_V2_FLOWCONTROL_OFF = 0
  • RS232_V2_FLOWCONTROL_SOFTWARE = 1
  • RS232_V2_FLOWCONTROL_HARDWARE = 2

Advanced Functions

int rs232_v2_set_buffer_config(RS232V2 *rs232_v2, uint16_t send_buffer_size, uint16_t receive_buffer_size)

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

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

The send buffer holds data that is given by rs232_v2_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 rs232_v2_read() or through RS232_V2_CALLBACK_READ callback.

The default configuration is 5120 byte (5kb) per buffer.

int rs232_v2_get_buffer_config(RS232V2 *rs232_v2, uint16_t *ret_send_buffer_size, uint16_t *ret_receive_buffer_size)

Returns the buffer configuration as set by rs232_v2_set_buffer_config().

int rs232_v2_get_buffer_status(RS232V2 *rs232_v2, uint16_t *ret_send_buffer_used, uint16_t *ret_receive_buffer_used)

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

See rs232_v2_set_buffer_config() for buffer size configuration.

int rs232_v2_get_error_count(RS232V2 *rs232_v2, uint32_t *ret_error_count_overrun, uint32_t *ret_error_count_parity)

Returns the current number of overrun and parity errors.

int rs232_v2_get_api_version(RS232V2 *rs232_v2, 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_v2_get_response_expected(RS232V2 *rs232_v2, 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_v2_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_v2_set_response_expected() for the list of function ID defines available for this function.

int rs232_v2_set_response_expected(RS232V2 *rs232_v2, 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.

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_V2_FUNCTION_ENABLE_READ_CALLBACK = 3
  • RS232_V2_FUNCTION_DISABLE_READ_CALLBACK = 4
  • RS232_V2_FUNCTION_SET_CONFIGURATION = 6
  • RS232_V2_FUNCTION_SET_BUFFER_CONFIG = 8
  • RS232_V2_FUNCTION_SET_WRITE_FIRMWARE_POINTER = 237
  • RS232_V2_FUNCTION_SET_STATUS_LED_CONFIG = 239
  • RS232_V2_FUNCTION_RESET = 243
  • RS232_V2_FUNCTION_WRITE_UID = 248
int rs232_v2_set_response_expected_all(RS232V2 *rs232_v2, bool response_expected)

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

int rs232_v2_get_spitfp_error_count(RS232V2 *rs232_v2, uint32_t *ret_error_count_ack_checksum, uint32_t *ret_error_count_message_checksum, uint32_t *ret_error_count_frame, uint32_t *ret_error_count_overflow)

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 rs232_v2_set_bootloader_mode(RS232V2 *rs232_v2, uint8_t mode, uint8_t *ret_status)

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 defines are available for this function:

  • RS232_V2_BOOTLOADER_MODE_BOOTLOADER = 0
  • RS232_V2_BOOTLOADER_MODE_FIRMWARE = 1
  • RS232_V2_BOOTLOADER_MODE_BOOTLOADER_WAIT_FOR_REBOOT = 2
  • RS232_V2_BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_REBOOT = 3
  • RS232_V2_BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_ERASE_AND_REBOOT = 4
  • RS232_V2_BOOTLOADER_STATUS_OK = 0
  • RS232_V2_BOOTLOADER_STATUS_INVALID_MODE = 1
  • RS232_V2_BOOTLOADER_STATUS_NO_CHANGE = 2
  • RS232_V2_BOOTLOADER_STATUS_ENTRY_FUNCTION_NOT_PRESENT = 3
  • RS232_V2_BOOTLOADER_STATUS_DEVICE_IDENTIFIER_INCORRECT = 4
  • RS232_V2_BOOTLOADER_STATUS_CRC_MISMATCH = 5
int rs232_v2_get_bootloader_mode(RS232V2 *rs232_v2, uint8_t *ret_mode)

Returns the current bootloader mode, see rs232_v2_set_bootloader_mode().

The following defines are available for this function:

  • RS232_V2_BOOTLOADER_MODE_BOOTLOADER = 0
  • RS232_V2_BOOTLOADER_MODE_FIRMWARE = 1
  • RS232_V2_BOOTLOADER_MODE_BOOTLOADER_WAIT_FOR_REBOOT = 2
  • RS232_V2_BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_REBOOT = 3
  • RS232_V2_BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_ERASE_AND_REBOOT = 4
int rs232_v2_set_write_firmware_pointer(RS232V2 *rs232_v2, uint32_t pointer)

Sets the firmware pointer for rs232_v2_write_firmware(). 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 rs232_v2_write_firmware(RS232V2 *rs232_v2, uint8_t data[64], uint8_t *ret_status)

Writes 64 Bytes of firmware at the position as written by rs232_v2_set_write_firmware_pointer() 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.

int rs232_v2_set_status_led_config(RS232V2 *rs232_v2, uint8_t config)

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 defines are available for this function:

  • RS232_V2_STATUS_LED_CONFIG_OFF = 0
  • RS232_V2_STATUS_LED_CONFIG_ON = 1
  • RS232_V2_STATUS_LED_CONFIG_SHOW_HEARTBEAT = 2
  • RS232_V2_STATUS_LED_CONFIG_SHOW_STATUS = 3
int rs232_v2_get_status_led_config(RS232V2 *rs232_v2, uint8_t *ret_config)

Returns the configuration as set by rs232_v2_set_status_led_config()

The following defines are available for this function:

  • RS232_V2_STATUS_LED_CONFIG_OFF = 0
  • RS232_V2_STATUS_LED_CONFIG_ON = 1
  • RS232_V2_STATUS_LED_CONFIG_SHOW_HEARTBEAT = 2
  • RS232_V2_STATUS_LED_CONFIG_SHOW_STATUS = 3
int rs232_v2_get_chip_temperature(RS232V2 *rs232_v2, int16_t *ret_temperature)

Returns the temperature in °C 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.

int rs232_v2_reset(RS232V2 *rs232_v2)

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!

int rs232_v2_write_uid(RS232V2 *rs232_v2, uint32_t uid)

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.

int rs232_v2_read_uid(RS232V2 *rs232_v2, uint32_t *ret_uid)

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

int rs232_v2_get_identity(RS232V2 *rs232_v2, 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_v2_register_callback(RS232V2 *rs232_v2, int16_t callback_id, void *function, void *user_data)

Registers the given function with the given callback_id. The user_data will be passed as the last parameter to the function.

The available callback IDs with corresponding function signatures are listed below.

int rs232_v2_enable_read_callback(RS232V2 *rs232_v2)

Enables the RS232_V2_CALLBACK_READ callback.

By default the callback is disabled.

int rs232_v2_disable_read_callback(RS232V2 *rs232_v2)

Disables the RS232_V2_CALLBACK_READ callback.

By default the callback is disabled.

int rs232_v2_is_read_callback_enabled(RS232V2 *rs232_v2, bool *ret_enabled)

Returns true if the RS232_V2_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_v2_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_v2_register_callback(&rs232_v2, RS232_V2_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_V2_CALLBACK_READ
void callback(char *message, uint16_t message_length, void *user_data)

This callback is called if new data is available.

To enable this callback, use rs232_v2_enable_read_callback().

RS232_V2_CALLBACK_ERROR_COUNT
void callback(uint32_t error_count_overrun, uint32_t error_count_parity, void *user_data)

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

Constants

RS232_V2_DEVICE_IDENTIFIER

This constant is used to identify a RS232 Bricklet 2.0.

The rs232_v2_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.

RS232_V2_DEVICE_DISPLAY_NAME

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