C/C++ - Laser Range Finder Bricklet

This is the description of the C/C++ API bindings for the Laser Range Finder Bricklet. General information and technical specifications for the Laser Range Finder 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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#define IPCON_EXPOSE_MILLISLEEP

#include <stdio.h>

#include "ip_connection.h"
#include "bricklet_laser_range_finder.h"

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

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

    // Create device object
    LaserRangeFinder lrf;
    laser_range_finder_create(&lrf, 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

    // Turn laser on and wait 250ms for very first measurement to be ready
    laser_range_finder_enable_laser(&lrf);
    millisleep(250);

    // Get current distance
    uint16_t distance;
    if(laser_range_finder_get_distance(&lrf, &distance) < 0) {
        fprintf(stderr, "Could not get distance, probably timeout\n");
        return 1;
    }

    printf("Distance: %u cm\n", distance);

    printf("Press key to exit\n");
    getchar();
    laser_range_finder_disable_laser(&lrf); // Turn laser off
    laser_range_finder_destroy(&lrf);
    ipcon_destroy(&ipcon); // Calls ipcon_disconnect internally
    return 0;
}

Callback

Download (example_callback.c)

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#define IPCON_EXPOSE_MILLISLEEP

#include <stdio.h>

#include "ip_connection.h"
#include "bricklet_laser_range_finder.h"

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

// Callback function for distance callback
void cb_distance(uint16_t distance, void *user_data) {
    (void)user_data; // avoid unused parameter warning

    printf("Distance: %u cm\n", distance);
}

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

    // Create device object
    LaserRangeFinder lrf;
    laser_range_finder_create(&lrf, 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

    // Turn laser on and wait 250ms for very first measurement to be ready
    laser_range_finder_enable_laser(&lrf);
    millisleep(250);

    // Register distance callback to function cb_distance
    laser_range_finder_register_callback(&lrf,
                                         LASER_RANGE_FINDER_CALLBACK_DISTANCE,
                                         (void *)cb_distance,
                                         NULL);

    // Set period for distance callback to 0.2s (200ms)
    // Note: The distance callback is only called every 0.2 seconds
    //       if the distance has changed since the last call!
    laser_range_finder_set_distance_callback_period(&lrf, 200);

    printf("Press key to exit\n");
    getchar();
    laser_range_finder_disable_laser(&lrf); // Turn laser off
    laser_range_finder_destroy(&lrf);
    ipcon_destroy(&ipcon); // Calls ipcon_disconnect internally
    return 0;
}

Threshold

Download (example_threshold.c)

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#define IPCON_EXPOSE_MILLISLEEP

#include <stdio.h>

#include "ip_connection.h"
#include "bricklet_laser_range_finder.h"

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

// Callback function for distance reached callback
void cb_distance_reached(uint16_t distance, void *user_data) {
    (void)user_data; // avoid unused parameter warning

    printf("Distance: %u cm\n", distance);
}

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

    // Create device object
    LaserRangeFinder lrf;
    laser_range_finder_create(&lrf, 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

    // Turn laser on and wait 250ms for very first measurement to be ready
    laser_range_finder_enable_laser(&lrf);
    millisleep(250);

    // Get threshold callbacks with a debounce time of 10 seconds (10000ms)
    laser_range_finder_set_debounce_period(&lrf, 10000);

    // Register distance reached callback to function cb_distance_reached
    laser_range_finder_register_callback(&lrf,
                                         LASER_RANGE_FINDER_CALLBACK_DISTANCE_REACHED,
                                         (void *)cb_distance_reached,
                                         NULL);

    // Configure threshold for distance "greater than 20 cm"
    laser_range_finder_set_distance_callback_threshold(&lrf, '>', 20, 0);

    printf("Press key to exit\n");
    getchar();
    laser_range_finder_disable_laser(&lrf); // Turn laser off
    laser_range_finder_destroy(&lrf);
    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 laser_range_finder_create(LaserRangeFinder *laser_range_finder, const char *uid, IPConnection *ipcon)

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

LaserRangeFinder laser_range_finder;
laser_range_finder_create(&laser_range_finder, "YOUR_DEVICE_UID", &ipcon);

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

void laser_range_finder_destroy(LaserRangeFinder *laser_range_finder)

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

int laser_range_finder_get_distance(LaserRangeFinder *laser_range_finder, uint16_t *ret_distance)

Returns the measured distance. The value has a range of 0 to 4000 and is given in cm.

Sensor hardware version 1 (see laser_range_finder_get_sensor_hardware_version()) cannot measure distance and velocity at the same time. Therefore, the distance mode has to be enabled using laser_range_finder_set_mode(). Sensor hardware version 3 can measure distance and velocity at the same time. Also the laser has to be enabled, see laser_range_finder_enable_laser().

If you want to get the distance periodically, it is recommended to use the LASER_RANGE_FINDER_CALLBACK_DISTANCE callback and set the period with laser_range_finder_set_distance_callback_period().

int laser_range_finder_get_velocity(LaserRangeFinder *laser_range_finder, int16_t *ret_velocity)

Returns the measured velocity. The value has a range of -12800 to 12700 and is given in 1/100 m/s.

Sensor hardware version 1 (see laser_range_finder_get_sensor_hardware_version()) cannot measure distance and velocity at the same time. Therefore, the velocity mode has to be enabled using laser_range_finder_set_mode(). Sensor hardware version 3 can measure distance and velocity at the same time, but the velocity measurement only produces stables results if a fixed measurement rate (see laser_range_finder_set_configuration()) is configured. Also the laser has to be enabled, see laser_range_finder_enable_laser().

If you want to get the velocity periodically, it is recommended to use the LASER_RANGE_FINDER_CALLBACK_VELOCITY callback and set the period with laser_range_finder_set_velocity_callback_period().

int laser_range_finder_set_mode(LaserRangeFinder *laser_range_finder, uint8_t mode)

Note

This function is only available if you have a LIDAR-Lite sensor with hardware version 1. Use laser_range_finder_set_configuration() for hardware version 3. You can check the sensor hardware version using laser_range_finder_get_sensor_hardware_version().

The LIDAR-Lite sensor (hardware version 1) has five different modes. One mode is for distance measurements and four modes are for velocity measurements with different ranges.

The following modes are available:

  • 0: Distance is measured with resolution 1.0 cm and range 0-400 cm
  • 1: Velocity is measured with resolution 0.1 m/s and range is 0-12.7 m/s
  • 2: Velocity is measured with resolution 0.25 m/s and range is 0-31.75 m/s
  • 3: Velocity is measured with resolution 0.5 m/s and range is 0-63.5 m/s
  • 4: Velocity is measured with resolution 1.0 m/s and range is 0-127 m/s

The default mode is 0 (distance is measured).

The following defines are available for this function:

  • LASER_RANGE_FINDER_MODE_DISTANCE = 0
  • LASER_RANGE_FINDER_MODE_VELOCITY_MAX_13MS = 1
  • LASER_RANGE_FINDER_MODE_VELOCITY_MAX_32MS = 2
  • LASER_RANGE_FINDER_MODE_VELOCITY_MAX_64MS = 3
  • LASER_RANGE_FINDER_MODE_VELOCITY_MAX_127MS = 4
int laser_range_finder_get_mode(LaserRangeFinder *laser_range_finder, uint8_t *ret_mode)

Returns the mode as set by laser_range_finder_set_mode().

The following defines are available for this function:

  • LASER_RANGE_FINDER_MODE_DISTANCE = 0
  • LASER_RANGE_FINDER_MODE_VELOCITY_MAX_13MS = 1
  • LASER_RANGE_FINDER_MODE_VELOCITY_MAX_32MS = 2
  • LASER_RANGE_FINDER_MODE_VELOCITY_MAX_64MS = 3
  • LASER_RANGE_FINDER_MODE_VELOCITY_MAX_127MS = 4
int laser_range_finder_enable_laser(LaserRangeFinder *laser_range_finder)

Activates the laser of the LIDAR.

We recommend that you wait 250ms after enabling the laser before the first call of laser_range_finder_get_distance() to ensure stable measurements.

int laser_range_finder_disable_laser(LaserRangeFinder *laser_range_finder)

Deactivates the laser of the LIDAR.

int laser_range_finder_is_laser_enabled(LaserRangeFinder *laser_range_finder, bool *ret_laser_enabled)

Returns true if the laser is enabled, false otherwise.

int laser_range_finder_set_configuration(LaserRangeFinder *laser_range_finder, uint8_t acquisition_count, bool enable_quick_termination, uint8_t threshold_value, uint16_t measurement_frequency)

Note

This function is only available if you have a LIDAR-Lite sensor with hardware version 3. Use laser_range_finder_set_mode() for hardware version 1. You can check the sensor hardware version using laser_range_finder_get_sensor_hardware_version().

The Aquisition Count defines the number of times the Laser Range Finder Bricklet will integrate acquisitions to find a correlation record peak. With a higher count, the Bricklet can measure longer distances. With a lower count, the rate increases. The allowed values are 1-255.

If you set Enable Quick Termination to true, the distance measurement will be terminated early if a high peak was already detected. This means that a higher measurement rate can be achieved and long distances can be measured at the same time. However, the chance of false-positive distance measurements increases.

Normally the distance is calculated with a detection algorithm that uses peak value, signal strength and noise. You can however also define a fixed Threshold Value. Set this to a low value if you want to measure the distance to something that has very little reflection (e.g. glass) and set it to a high value if you want to measure the distance to something with a very high reflection (e.g. mirror). Set this to 0 to use the default algorithm. The other allowed values are 1-255.

Set the Measurement Frequency in Hz to force a fixed measurement rate. If set to 0, the Laser Range Finder Bricklet will use the optimal frequency according to the other configurations and the actual measured distance. Since the rate is not fixed in this case, the velocity measurement is not stable. For a stable velocity measurement you should set a fixed measurement frequency. The lower the frequency, the higher is the resolution of the calculated velocity. The allowed values are 10Hz-500Hz (and 0 to turn the fixed frequency off).

The default values for Acquisition Count, Enable Quick Termination, Threshold Value and Measurement Frequency are 128, false, 0 and 0.

New in version 2.0.3 (Plugin).

int laser_range_finder_get_configuration(LaserRangeFinder *laser_range_finder, uint8_t *ret_acquisition_count, bool *ret_enable_quick_termination, uint8_t *ret_threshold_value, uint16_t *ret_measurement_frequency)

Returns the configuration as set by laser_range_finder_set_configuration().

New in version 2.0.3 (Plugin).

Advanced Functions

int laser_range_finder_set_moving_average(LaserRangeFinder *laser_range_finder, uint8_t distance_average_length, uint8_t velocity_average_length)

Sets the length of a moving averaging for the distance and velocity.

Setting the length to 0 will turn the averaging completely off. With less averaging, there is more noise on the data.

The range for the averaging is 0-30.

The default value is 10.

int laser_range_finder_get_moving_average(LaserRangeFinder *laser_range_finder, uint8_t *ret_distance_average_length, uint8_t *ret_velocity_average_length)

Returns the length moving average as set by laser_range_finder_set_moving_average().

int laser_range_finder_get_sensor_hardware_version(LaserRangeFinder *laser_range_finder, uint8_t *ret_version)

Returns the LIDAR-Lite hardware version.

The following defines are available for this function:

  • LASER_RANGE_FINDER_VERSION_1 = 1
  • LASER_RANGE_FINDER_VERSION_3 = 3

New in version 2.0.3 (Plugin).

int laser_range_finder_get_api_version(LaserRangeFinder *laser_range_finder, 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 laser_range_finder_get_response_expected(LaserRangeFinder *laser_range_finder, 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 laser_range_finder_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 laser_range_finder_set_response_expected() for the list of function ID defines available for this function.

int laser_range_finder_set_response_expected(LaserRangeFinder *laser_range_finder, 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:

  • LASER_RANGE_FINDER_FUNCTION_SET_DISTANCE_CALLBACK_PERIOD = 3
  • LASER_RANGE_FINDER_FUNCTION_SET_VELOCITY_CALLBACK_PERIOD = 5
  • LASER_RANGE_FINDER_FUNCTION_SET_DISTANCE_CALLBACK_THRESHOLD = 7
  • LASER_RANGE_FINDER_FUNCTION_SET_VELOCITY_CALLBACK_THRESHOLD = 9
  • LASER_RANGE_FINDER_FUNCTION_SET_DEBOUNCE_PERIOD = 11
  • LASER_RANGE_FINDER_FUNCTION_SET_MOVING_AVERAGE = 13
  • LASER_RANGE_FINDER_FUNCTION_SET_MODE = 15
  • LASER_RANGE_FINDER_FUNCTION_ENABLE_LASER = 17
  • LASER_RANGE_FINDER_FUNCTION_DISABLE_LASER = 18
  • LASER_RANGE_FINDER_FUNCTION_SET_CONFIGURATION = 25
int laser_range_finder_set_response_expected_all(LaserRangeFinder *laser_range_finder, bool response_expected)

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

int laser_range_finder_get_identity(LaserRangeFinder *laser_range_finder, 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 laser_range_finder_register_callback(LaserRangeFinder *laser_range_finder, 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 laser_range_finder_set_distance_callback_period(LaserRangeFinder *laser_range_finder, uint32_t period)

Sets the period in ms with which the LASER_RANGE_FINDER_CALLBACK_DISTANCE callback is triggered periodically. A value of 0 turns the callback off.

The LASER_RANGE_FINDER_CALLBACK_DISTANCE callback is only triggered if the distance value has changed since the last triggering.

The default value is 0.

int laser_range_finder_get_distance_callback_period(LaserRangeFinder *laser_range_finder, uint32_t *ret_period)

Returns the period as set by laser_range_finder_set_distance_callback_period().

int laser_range_finder_set_velocity_callback_period(LaserRangeFinder *laser_range_finder, uint32_t period)

Sets the period in ms with which the LASER_RANGE_FINDER_CALLBACK_VELOCITY callback is triggered periodically. A value of 0 turns the callback off.

The LASER_RANGE_FINDER_CALLBACK_VELOCITY callback is only triggered if the velocity value has changed since the last triggering.

The default value is 0.

int laser_range_finder_get_velocity_callback_period(LaserRangeFinder *laser_range_finder, uint32_t *ret_period)

Returns the period as set by laser_range_finder_set_velocity_callback_period().

int laser_range_finder_set_distance_callback_threshold(LaserRangeFinder *laser_range_finder, char option, uint16_t min, uint16_t max)

Sets the thresholds for the LASER_RANGE_FINDER_CALLBACK_DISTANCE_REACHED callback.

The following options are possible:

Option Description
'x' Callback is turned off
'o' Callback is triggered when the distance value is outside the min and max values
'i' Callback is triggered when the distance value is inside the min and max values
'<' Callback is triggered when the distance value is smaller than the min value (max is ignored)
'>' Callback is triggered when the distance value is greater than the min value (max is ignored)

The default value is ('x', 0, 0).

The following defines are available for this function:

  • LASER_RANGE_FINDER_THRESHOLD_OPTION_OFF = 'x'
  • LASER_RANGE_FINDER_THRESHOLD_OPTION_OUTSIDE = 'o'
  • LASER_RANGE_FINDER_THRESHOLD_OPTION_INSIDE = 'i'
  • LASER_RANGE_FINDER_THRESHOLD_OPTION_SMALLER = '<'
  • LASER_RANGE_FINDER_THRESHOLD_OPTION_GREATER = '>'
int laser_range_finder_get_distance_callback_threshold(LaserRangeFinder *laser_range_finder, char *ret_option, uint16_t *ret_min, uint16_t *ret_max)

Returns the threshold as set by laser_range_finder_set_distance_callback_threshold().

The following defines are available for this function:

  • LASER_RANGE_FINDER_THRESHOLD_OPTION_OFF = 'x'
  • LASER_RANGE_FINDER_THRESHOLD_OPTION_OUTSIDE = 'o'
  • LASER_RANGE_FINDER_THRESHOLD_OPTION_INSIDE = 'i'
  • LASER_RANGE_FINDER_THRESHOLD_OPTION_SMALLER = '<'
  • LASER_RANGE_FINDER_THRESHOLD_OPTION_GREATER = '>'
int laser_range_finder_set_velocity_callback_threshold(LaserRangeFinder *laser_range_finder, char option, int16_t min, int16_t max)

Sets the thresholds for the LASER_RANGE_FINDER_CALLBACK_VELOCITY_REACHED callback.

The following options are possible:

Option Description
'x' Callback is turned off
'o' Callback is triggered when the velocity is outside the min and max values
'i' Callback is triggered when the velocity is inside the min and max values
'<' Callback is triggered when the velocity is smaller than the min value (max is ignored)
'>' Callback is triggered when the velocity is greater than the min value (max is ignored)

The default value is ('x', 0, 0).

The following defines are available for this function:

  • LASER_RANGE_FINDER_THRESHOLD_OPTION_OFF = 'x'
  • LASER_RANGE_FINDER_THRESHOLD_OPTION_OUTSIDE = 'o'
  • LASER_RANGE_FINDER_THRESHOLD_OPTION_INSIDE = 'i'
  • LASER_RANGE_FINDER_THRESHOLD_OPTION_SMALLER = '<'
  • LASER_RANGE_FINDER_THRESHOLD_OPTION_GREATER = '>'
int laser_range_finder_get_velocity_callback_threshold(LaserRangeFinder *laser_range_finder, char *ret_option, int16_t *ret_min, int16_t *ret_max)

Returns the threshold as set by laser_range_finder_set_velocity_callback_threshold().

The following defines are available for this function:

  • LASER_RANGE_FINDER_THRESHOLD_OPTION_OFF = 'x'
  • LASER_RANGE_FINDER_THRESHOLD_OPTION_OUTSIDE = 'o'
  • LASER_RANGE_FINDER_THRESHOLD_OPTION_INSIDE = 'i'
  • LASER_RANGE_FINDER_THRESHOLD_OPTION_SMALLER = '<'
  • LASER_RANGE_FINDER_THRESHOLD_OPTION_GREATER = '>'
int laser_range_finder_set_debounce_period(LaserRangeFinder *laser_range_finder, uint32_t debounce)

Sets the period in ms with which the threshold callbacks

are triggered, if the thresholds

keep being reached.

The default value is 100.

int laser_range_finder_get_debounce_period(LaserRangeFinder *laser_range_finder, uint32_t *ret_debounce)

Returns the debounce period as set by laser_range_finder_set_debounce_period().

Callbacks

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

laser_range_finder_register_callback(&laser_range_finder, LASER_RANGE_FINDER_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.

LASER_RANGE_FINDER_CALLBACK_DISTANCE
void callback(uint16_t distance, void *user_data)

This callback is triggered periodically with the period that is set by laser_range_finder_set_distance_callback_period(). The parameter is the distance value of the sensor.

The LASER_RANGE_FINDER_CALLBACK_DISTANCE callback is only triggered if the distance value has changed since the last triggering.

LASER_RANGE_FINDER_CALLBACK_VELOCITY
void callback(int16_t velocity, void *user_data)

This callback is triggered periodically with the period that is set by laser_range_finder_set_velocity_callback_period(). The parameter is the velocity value of the sensor.

The LASER_RANGE_FINDER_CALLBACK_VELOCITY callback is only triggered if the velocity has changed since the last triggering.

LASER_RANGE_FINDER_CALLBACK_DISTANCE_REACHED
void callback(uint16_t distance, void *user_data)

This callback is triggered when the threshold as set by laser_range_finder_set_distance_callback_threshold() is reached. The parameter is the distance value of the sensor.

If the threshold keeps being reached, the callback is triggered periodically with the period as set by laser_range_finder_set_debounce_period().

LASER_RANGE_FINDER_CALLBACK_VELOCITY_REACHED
void callback(int16_t velocity, void *user_data)

This callback is triggered when the threshold as set by laser_range_finder_set_velocity_callback_threshold() is reached. The parameter is the velocity value of the sensor.

If the threshold keeps being reached, the callback is triggered periodically with the period as set by laser_range_finder_set_debounce_period().

Constants

LASER_RANGE_FINDER_DEVICE_IDENTIFIER

This constant is used to identify a Laser Range Finder Bricklet.

The laser_range_finder_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.

LASER_RANGE_FINDER_DEVICE_DISPLAY_NAME

This constant represents the human readable name of a Laser Range Finder Bricklet.