C/C++ - Tilt Bricklet

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

Simple

Download (example_simple.c)

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#include <stdio.h>

#include "ip_connection.h"
#include "bricklet_tilt.h"

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

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

    // Create device object
    Tilt t;
    tilt_create(&t, 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

    // Get current tilt state
    uint8_t state;
    if(tilt_get_tilt_state(&t, &state) < 0) {
        fprintf(stderr, "Could not get tilt state, probably timeout\n");
        return 1;
    }

    if(state == TILT_TILT_STATE_CLOSED) {
        printf("Tilt State: Closed\n");
    } else if(state == TILT_TILT_STATE_OPEN) {
        printf("Tilt State: Open\n");
    } else if(state == TILT_TILT_STATE_CLOSED_VIBRATING) {
        printf("Tilt State: Closed Vibrating\n");
    }

    printf("Press key to exit\n");
    getchar();
    tilt_destroy(&t);
    ipcon_destroy(&ipcon); // Calls ipcon_disconnect internally
    return 0;
}

Callback

Download (example_callback.c)

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#include <stdio.h>

#include "ip_connection.h"
#include "bricklet_tilt.h"

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

// Callback function for tilt state callback
void cb_tilt_state(uint8_t state, void *user_data) {
    (void)user_data; // avoid unused parameter warning

    if(state == TILT_TILT_STATE_CLOSED) {
        printf("Tilt State: Closed\n");
    } else if(state == TILT_TILT_STATE_OPEN) {
        printf("Tilt State: Open\n");
    } else if(state == TILT_TILT_STATE_CLOSED_VIBRATING) {
        printf("Tilt State: Closed Vibrating\n");
    }
}

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

    // Create device object
    Tilt t;
    tilt_create(&t, 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

    // Enable tilt state callback
    tilt_enable_tilt_state_callback(&t);

    // Register tilt state callback to function cb_tilt_state
    tilt_register_callback(&t,
                           TILT_CALLBACK_TILT_STATE,
                           (void *)cb_tilt_state,
                           NULL);

    printf("Press key to exit\n");
    getchar();
    tilt_destroy(&t);
    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 tilt_create(Tilt *tilt, const char *uid, IPConnection *ipcon)

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

Tilt tilt;
tilt_create(&tilt, "YOUR_DEVICE_UID", &ipcon);

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

void tilt_destroy(Tilt *tilt)

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

int tilt_get_tilt_state(Tilt *tilt, uint8_t *ret_state)

Returns the current tilt state. The state can either be

  • 0 = Closed: The ball in the tilt switch closes the circuit.
  • 1 = Open: The ball in the tilt switch does not close the circuit.
  • 2 = Closed Vibrating: The tilt switch is in motion (rapid change between open and close).
Tilt states

The following defines are available for this function:

  • TILT_TILT_STATE_CLOSED = 0
  • TILT_TILT_STATE_OPEN = 1
  • TILT_TILT_STATE_CLOSED_VIBRATING = 2

Advanced Functions

int tilt_get_api_version(Tilt *tilt, 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 tilt_get_response_expected(Tilt *tilt, 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 tilt_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 tilt_set_response_expected() for the list of function ID defines available for this function.

int tilt_set_response_expected(Tilt *tilt, 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:

  • TILT_FUNCTION_ENABLE_TILT_STATE_CALLBACK = 2
  • TILT_FUNCTION_DISABLE_TILT_STATE_CALLBACK = 3
int tilt_set_response_expected_all(Tilt *tilt, bool response_expected)

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

int tilt_get_identity(Tilt *tilt, 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 tilt_register_callback(Tilt *tilt, 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 tilt_enable_tilt_state_callback(Tilt *tilt)

Enables the TILT_CALLBACK_TILT_STATE callback.

int tilt_disable_tilt_state_callback(Tilt *tilt)

Disables the TILT_CALLBACK_TILT_STATE callback.

int tilt_is_tilt_state_callback_enabled(Tilt *tilt, bool *ret_enabled)

Returns true if the TILT_CALLBACK_TILT_STATE callback is enabled.

Callbacks

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

tilt_register_callback(&tilt, TILT_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.

TILT_CALLBACK_TILT_STATE
void callback(uint8_t state, void *user_data)

This callback provides the current tilt state. It is called every time the state changes.

See tilt_get_tilt_state() for a description of the states.

The following defines are available for this function:

  • TILT_TILT_STATE_CLOSED = 0
  • TILT_TILT_STATE_OPEN = 1
  • TILT_TILT_STATE_CLOSED_VIBRATING = 2

Constants

TILT_DEVICE_IDENTIFIER

This constant is used to identify a Tilt Bricklet.

The tilt_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.

TILT_DEVICE_DISPLAY_NAME

This constant represents the human readable name of a Tilt Bricklet.