C/C++ - Motion Detector Bricklet

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

Callback

Download (example_callback.c)

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#include <stdio.h>

#include "ip_connection.h"
#include "bricklet_motion_detector.h"

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

// Callback function for motion detected callback
void cb_motion_detected(void *user_data) {
    (void)user_data; // avoid unused parameter warning

    printf("Motion Detected\n");
}

// Callback function for detection cycle ended callback
void cb_detection_cycle_ended(void *user_data) {
    (void)user_data; // avoid unused parameter warning

    printf("Detection Cycle Ended (next detection possible in ~3 seconds)\n");
}

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

    // Create device object
    MotionDetector md;
    motion_detector_create(&md, 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 motion detected callback to function cb_motion_detected
    motion_detector_register_callback(&md,
                                      MOTION_DETECTOR_CALLBACK_MOTION_DETECTED,
                                      (void *)cb_motion_detected,
                                      NULL);

    // Register detection cycle ended callback to function cb_detection_cycle_ended
    motion_detector_register_callback(&md,
                                      MOTION_DETECTOR_CALLBACK_DETECTION_CYCLE_ENDED,
                                      (void *)cb_detection_cycle_ended,
                                      NULL);

    printf("Press key to exit\n");
    getchar();
    motion_detector_destroy(&md);
    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 motion_detector_create(MotionDetector *motion_detector, const char *uid, IPConnection *ipcon)

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

MotionDetector motion_detector;
motion_detector_create(&motion_detector, "YOUR_DEVICE_UID", &ipcon);

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

void motion_detector_destroy(MotionDetector *motion_detector)

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

int motion_detector_get_motion_detected(MotionDetector *motion_detector, uint8_t *ret_motion)

Returns 1 if a motion was detected. How long this returns 1 after a motion was detected can be adjusted with one of the small potentiometers on the Motion Detector Bricklet, see here.

There is also a blue LED on the Bricklet that is on as long as the Bricklet is in the "motion detected" state.

The following defines are available for this function:

  • MOTION_DETECTOR_MOTION_NOT_DETECTED = 0
  • MOTION_DETECTOR_MOTION_DETECTED = 1

Advanced Functions

int motion_detector_set_status_led_config(MotionDetector *motion_detector, uint8_t config)

Sets the status led configuration.

By default the status LED turns on if a motion is detected and off is no motion is detected.

You can also turn the LED permanently on/off.

The following defines are available for this function:

  • MOTION_DETECTOR_STATUS_LED_CONFIG_OFF = 0
  • MOTION_DETECTOR_STATUS_LED_CONFIG_ON = 1
  • MOTION_DETECTOR_STATUS_LED_CONFIG_SHOW_STATUS = 2

New in version 2.0.1 (Plugin).

int motion_detector_get_status_led_config(MotionDetector *motion_detector, uint8_t *ret_config)

Returns the configuration as set by motion_detector_set_status_led_config().

The following defines are available for this function:

  • MOTION_DETECTOR_STATUS_LED_CONFIG_OFF = 0
  • MOTION_DETECTOR_STATUS_LED_CONFIG_ON = 1
  • MOTION_DETECTOR_STATUS_LED_CONFIG_SHOW_STATUS = 2

New in version 2.0.1 (Plugin).

int motion_detector_get_api_version(MotionDetector *motion_detector, 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 motion_detector_get_response_expected(MotionDetector *motion_detector, 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 motion_detector_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 motion_detector_set_response_expected() for the list of function ID defines available for this function.

int motion_detector_set_response_expected(MotionDetector *motion_detector, 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:

  • MOTION_DETECTOR_FUNCTION_SET_STATUS_LED_CONFIG = 4
int motion_detector_set_response_expected_all(MotionDetector *motion_detector, bool response_expected)

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

int motion_detector_get_identity(MotionDetector *motion_detector, 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 motion_detector_register_callback(MotionDetector *motion_detector, 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.

Callbacks

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

motion_detector_register_callback(&motion_detector, MOTION_DETECTOR_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.

MOTION_DETECTOR_CALLBACK_MOTION_DETECTED
void callback(void *user_data)

This callback is called after a motion was detected.

MOTION_DETECTOR_CALLBACK_DETECTION_CYCLE_ENDED
void callback(void *user_data)

This callback is called when the detection cycle ended. When this callback is called, a new motion can be detected again after approximately 2 seconds.

Constants

MOTION_DETECTOR_DEVICE_IDENTIFIER

This constant is used to identify a Motion Detector Bricklet.

The motion_detector_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.

MOTION_DETECTOR_DEVICE_DISPLAY_NAME

This constant represents the human readable name of a Motion Detector Bricklet.