C/C++ - Dual Button Bricklet 2.0

This is the description of the C/C++ API bindings for the Dual Button Bricklet 2.0. General information and technical specifications for the Dual Button 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).

Callback

Download (example_callback.c)

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#include <stdio.h>

#include "ip_connection.h"
#include "bricklet_dual_button_v2.h"

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

// Callback function for state changed callback
void cb_state_changed(uint8_t button_l, uint8_t button_r, uint8_t led_l, uint8_t led_r,
                      void *user_data) {
    (void)led_l; (void)led_r; (void)user_data; // avoid unused parameter warning

    if(button_l == DUAL_BUTTON_V2_BUTTON_STATE_PRESSED) {
        printf("Left Button: Pressed\n");
    } else if(button_l == DUAL_BUTTON_V2_BUTTON_STATE_RELEASED) {
        printf("Left Button: Released\n");
    }

    if(button_r == DUAL_BUTTON_V2_BUTTON_STATE_PRESSED) {
        printf("Right Button: Pressed\n");
    } else if(button_r == DUAL_BUTTON_V2_BUTTON_STATE_RELEASED) {
        printf("Right Button: Released\n");
    }

    printf("\n");
}

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

    // Create device object
    DualButtonV2 db;
    dual_button_v2_create(&db, 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 state changed callback to function cb_state_changed
    dual_button_v2_register_callback(&db,
                                     DUAL_BUTTON_V2_CALLBACK_STATE_CHANGED,
                                     (void *)cb_state_changed,
                                     NULL);

    printf("Press key to exit\n");
    getchar();
    dual_button_v2_destroy(&db);
    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 dual_button_v2_create(DualButtonV2 *dual_button_v2, const char *uid, IPConnection *ipcon)

Creates the device object dual_button_v2 with the unique device ID uid and adds it to the IPConnection ipcon:

DualButtonV2 dual_button_v2;
dual_button_v2_create(&dual_button_v2, "YOUR_DEVICE_UID", &ipcon);

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

void dual_button_v2_destroy(DualButtonV2 *dual_button_v2)

Removes the device object dual_button_v2 from its IPConnection and destroys it. The device object cannot be used anymore afterwards.

int dual_button_v2_set_led_state(DualButtonV2 *dual_button_v2, uint8_t led_l, uint8_t led_r)

Sets the state of the LEDs. Possible states are:

  • 0 = AutoToggleOn: Enables auto toggle with initially enabled LED.
  • 1 = AutoToggleOff: Activates auto toggle with initially disabled LED.
  • 2 = On: Enables LED (auto toggle is disabled).
  • 3 = Off: Disables LED (auto toggle is disabled).

In auto toggle mode the LED is toggled automatically at each press of a button.

If you just want to set one of the LEDs and don't know the current state of the other LED, you can get the state with dual_button_v2_get_led_state() or you can use dual_button_v2_set_selected_led_state().

The default value is (1, 1).

The following defines are available for this function:

  • DUAL_BUTTON_V2_LED_STATE_AUTO_TOGGLE_ON = 0
  • DUAL_BUTTON_V2_LED_STATE_AUTO_TOGGLE_OFF = 1
  • DUAL_BUTTON_V2_LED_STATE_ON = 2
  • DUAL_BUTTON_V2_LED_STATE_OFF = 3
int dual_button_v2_get_led_state(DualButtonV2 *dual_button_v2, uint8_t *ret_led_l, uint8_t *ret_led_r)

Returns the current state of the LEDs, as set by dual_button_v2_set_led_state().

The following defines are available for this function:

  • DUAL_BUTTON_V2_LED_STATE_AUTO_TOGGLE_ON = 0
  • DUAL_BUTTON_V2_LED_STATE_AUTO_TOGGLE_OFF = 1
  • DUAL_BUTTON_V2_LED_STATE_ON = 2
  • DUAL_BUTTON_V2_LED_STATE_OFF = 3
int dual_button_v2_get_button_state(DualButtonV2 *dual_button_v2, uint8_t *ret_button_l, uint8_t *ret_button_r)

Returns the current state for both buttons. Possible states are:

  • 0 = pressed
  • 1 = released

The following defines are available for this function:

  • DUAL_BUTTON_V2_BUTTON_STATE_PRESSED = 0
  • DUAL_BUTTON_V2_BUTTON_STATE_RELEASED = 1

Advanced Functions

int dual_button_v2_set_selected_led_state(DualButtonV2 *dual_button_v2, uint8_t led, uint8_t state)

Sets the state of the selected LED (0 or 1).

The other LED remains untouched.

The following defines are available for this function:

  • DUAL_BUTTON_V2_LED_LEFT = 0
  • DUAL_BUTTON_V2_LED_RIGHT = 1
  • DUAL_BUTTON_V2_LED_STATE_AUTO_TOGGLE_ON = 0
  • DUAL_BUTTON_V2_LED_STATE_AUTO_TOGGLE_OFF = 1
  • DUAL_BUTTON_V2_LED_STATE_ON = 2
  • DUAL_BUTTON_V2_LED_STATE_OFF = 3
int dual_button_v2_get_api_version(DualButtonV2 *dual_button_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 dual_button_v2_get_response_expected(DualButtonV2 *dual_button_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 dual_button_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 dual_button_v2_set_response_expected() for the list of function ID defines available for this function.

int dual_button_v2_set_response_expected(DualButtonV2 *dual_button_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:

  • DUAL_BUTTON_V2_FUNCTION_SET_LED_STATE = 1
  • DUAL_BUTTON_V2_FUNCTION_SET_SELECTED_LED_STATE = 5
  • DUAL_BUTTON_V2_FUNCTION_SET_STATE_CHANGED_CALLBACK_CONFIGURATION = 6
  • DUAL_BUTTON_V2_FUNCTION_SET_WRITE_FIRMWARE_POINTER = 237
  • DUAL_BUTTON_V2_FUNCTION_SET_STATUS_LED_CONFIG = 239
  • DUAL_BUTTON_V2_FUNCTION_RESET = 243
  • DUAL_BUTTON_V2_FUNCTION_WRITE_UID = 248
int dual_button_v2_set_response_expected_all(DualButtonV2 *dual_button_v2, bool response_expected)

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

int dual_button_v2_get_spitfp_error_count(DualButtonV2 *dual_button_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 dual_button_v2_set_bootloader_mode(DualButtonV2 *dual_button_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:

  • DUAL_BUTTON_V2_BOOTLOADER_MODE_BOOTLOADER = 0
  • DUAL_BUTTON_V2_BOOTLOADER_MODE_FIRMWARE = 1
  • DUAL_BUTTON_V2_BOOTLOADER_MODE_BOOTLOADER_WAIT_FOR_REBOOT = 2
  • DUAL_BUTTON_V2_BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_REBOOT = 3
  • DUAL_BUTTON_V2_BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_ERASE_AND_REBOOT = 4
  • DUAL_BUTTON_V2_BOOTLOADER_STATUS_OK = 0
  • DUAL_BUTTON_V2_BOOTLOADER_STATUS_INVALID_MODE = 1
  • DUAL_BUTTON_V2_BOOTLOADER_STATUS_NO_CHANGE = 2
  • DUAL_BUTTON_V2_BOOTLOADER_STATUS_ENTRY_FUNCTION_NOT_PRESENT = 3
  • DUAL_BUTTON_V2_BOOTLOADER_STATUS_DEVICE_IDENTIFIER_INCORRECT = 4
  • DUAL_BUTTON_V2_BOOTLOADER_STATUS_CRC_MISMATCH = 5
int dual_button_v2_get_bootloader_mode(DualButtonV2 *dual_button_v2, uint8_t *ret_mode)

Returns the current bootloader mode, see dual_button_v2_set_bootloader_mode().

The following defines are available for this function:

  • DUAL_BUTTON_V2_BOOTLOADER_MODE_BOOTLOADER = 0
  • DUAL_BUTTON_V2_BOOTLOADER_MODE_FIRMWARE = 1
  • DUAL_BUTTON_V2_BOOTLOADER_MODE_BOOTLOADER_WAIT_FOR_REBOOT = 2
  • DUAL_BUTTON_V2_BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_REBOOT = 3
  • DUAL_BUTTON_V2_BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_ERASE_AND_REBOOT = 4
int dual_button_v2_set_write_firmware_pointer(DualButtonV2 *dual_button_v2, uint32_t pointer)

Sets the firmware pointer for dual_button_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 dual_button_v2_write_firmware(DualButtonV2 *dual_button_v2, uint8_t data[64], uint8_t *ret_status)

Writes 64 Bytes of firmware at the position as written by dual_button_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 dual_button_v2_set_status_led_config(DualButtonV2 *dual_button_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:

  • DUAL_BUTTON_V2_STATUS_LED_CONFIG_OFF = 0
  • DUAL_BUTTON_V2_STATUS_LED_CONFIG_ON = 1
  • DUAL_BUTTON_V2_STATUS_LED_CONFIG_SHOW_HEARTBEAT = 2
  • DUAL_BUTTON_V2_STATUS_LED_CONFIG_SHOW_STATUS = 3
int dual_button_v2_get_status_led_config(DualButtonV2 *dual_button_v2, uint8_t *ret_config)

Returns the configuration as set by dual_button_v2_set_status_led_config()

The following defines are available for this function:

  • DUAL_BUTTON_V2_STATUS_LED_CONFIG_OFF = 0
  • DUAL_BUTTON_V2_STATUS_LED_CONFIG_ON = 1
  • DUAL_BUTTON_V2_STATUS_LED_CONFIG_SHOW_HEARTBEAT = 2
  • DUAL_BUTTON_V2_STATUS_LED_CONFIG_SHOW_STATUS = 3
int dual_button_v2_get_chip_temperature(DualButtonV2 *dual_button_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 dual_button_v2_reset(DualButtonV2 *dual_button_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 dual_button_v2_write_uid(DualButtonV2 *dual_button_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 dual_button_v2_read_uid(DualButtonV2 *dual_button_v2, uint32_t *ret_uid)

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

int dual_button_v2_get_identity(DualButtonV2 *dual_button_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 dual_button_v2_register_callback(DualButtonV2 *dual_button_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 dual_button_v2_set_state_changed_callback_configuration(DualButtonV2 *dual_button_v2, bool enabled)

If you enable this callback, the DUAL_BUTTON_V2_CALLBACK_STATE_CHANGED callback is triggered every time a button is pressed/released

By default this callback is disabled.

int dual_button_v2_get_state_changed_callback_configuration(DualButtonV2 *dual_button_v2, bool *ret_enabled)

Returns the configuration as set by dual_button_v2_set_state_changed_callback_configuration().

Callbacks

Callbacks can be registered to receive time critical or recurring data from the device. The registration is done with the dual_button_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);
}

dual_button_v2_register_callback(&dual_button_v2, DUAL_BUTTON_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.

DUAL_BUTTON_V2_CALLBACK_STATE_CHANGED
void callback(uint8_t button_l, uint8_t button_r, uint8_t led_l, uint8_t led_r, void *user_data)

This callback is called whenever a button is pressed.

Possible states for buttons are:

  • 0 = pressed
  • 1 = released

Possible states for LEDs are:

  • 0 = AutoToggleOn: Auto toggle enabled and LED on.
  • 1 = AutoToggleOff: Auto toggle enabled and LED off.
  • 2 = On: LED on (auto toggle is disabled).
  • 3 = Off: LED off (auto toggle is disabled).

This callback can be enabled with dual_button_v2_set_state_changed_callback_configuration().

The following defines are available for this function:

  • DUAL_BUTTON_V2_BUTTON_STATE_PRESSED = 0
  • DUAL_BUTTON_V2_BUTTON_STATE_RELEASED = 1
  • DUAL_BUTTON_V2_LED_STATE_AUTO_TOGGLE_ON = 0
  • DUAL_BUTTON_V2_LED_STATE_AUTO_TOGGLE_OFF = 1
  • DUAL_BUTTON_V2_LED_STATE_ON = 2
  • DUAL_BUTTON_V2_LED_STATE_OFF = 3

Constants

DUAL_BUTTON_V2_DEVICE_IDENTIFIER

This constant is used to identify a Dual Button Bricklet 2.0.

The dual_button_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.

DUAL_BUTTON_V2_DEVICE_DISPLAY_NAME

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