Rust - Laser Range Finder Bricklet

This is the description of the Rust 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 Rust API bindings is part of their general description. Additional documentation can be found on docs.rs.

Examples

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

Simple

Download (example_simple.rs)

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use std::{error::Error, io, thread, time::Duration};
use tinkerforge::{ip_connection::IpConnection, laser_range_finder_bricklet::*};

const HOST: &str = "localhost";
const PORT: u16 = 4223;
const UID: &str = "XYZ"; // Change XYZ to the UID of your Laser Range Finder Bricklet.

fn main() -> Result<(), Box<dyn Error>> {
    let ipcon = IpConnection::new(); // Create IP connection.
    let lrf = LaserRangeFinderBricklet::new(UID, &ipcon); // Create device object.

    ipcon.connect((HOST, PORT)).recv()??; // Connect to brickd.
                                          // Don't use device before ipcon is connected.

    // Turn laser on and wait 250ms for very first measurement to be ready
    lrf.enable_laser();
    thread::sleep(Duration::from_millis(250));

    // Get current distance.
    let distance = lrf.get_distance().recv()?;
    println!("Distance: {} cm", distance);

    println!("Press enter to exit.");
    let mut _input = String::new();
    io::stdin().read_line(&mut _input)?;
    lrf.disable_laser(); // Turn laser off
    ipcon.disconnect();
    Ok(())
}

Callback

Download (example_callback.rs)

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use std::{error::Error, io, thread, time::Duration};
use tinkerforge::{ip_connection::IpConnection, laser_range_finder_bricklet::*};

const HOST: &str = "localhost";
const PORT: u16 = 4223;
const UID: &str = "XYZ"; // Change XYZ to the UID of your Laser Range Finder Bricklet.

fn main() -> Result<(), Box<dyn Error>> {
    let ipcon = IpConnection::new(); // Create IP connection.
    let lrf = LaserRangeFinderBricklet::new(UID, &ipcon); // Create device object.

    ipcon.connect((HOST, PORT)).recv()??; // Connect to brickd.
                                          // Don't use device before ipcon is connected.

    // Turn laser on and wait 250ms for very first measurement to be ready
    lrf.enable_laser();
    thread::sleep(Duration::from_millis(250));

    let distance_receiver = lrf.get_distance_callback_receiver();

    // Spawn thread to handle received callback messages.
    // This thread ends when the `lrf` object
    // is dropped, so there is no need for manual cleanup.
    thread::spawn(move || {
        for distance in distance_receiver {
            println!("Distance: {} cm", distance);
        }
    });

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

    println!("Press enter to exit.");
    let mut _input = String::new();
    io::stdin().read_line(&mut _input)?;
    lrf.disable_laser(); // Turn laser off
    ipcon.disconnect();
    Ok(())
}

Threshold

Download (example_threshold.rs)

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use std::{error::Error, io, thread, time::Duration};
use tinkerforge::{ip_connection::IpConnection, laser_range_finder_bricklet::*};

const HOST: &str = "localhost";
const PORT: u16 = 4223;
const UID: &str = "XYZ"; // Change XYZ to the UID of your Laser Range Finder Bricklet.

fn main() -> Result<(), Box<dyn Error>> {
    let ipcon = IpConnection::new(); // Create IP connection.
    let lrf = LaserRangeFinderBricklet::new(UID, &ipcon); // Create device object.

    ipcon.connect((HOST, PORT)).recv()??; // Connect to brickd.
                                          // Don't use device before ipcon is connected.

    // Turn laser on and wait 250ms for very first measurement to be ready
    lrf.enable_laser();
    thread::sleep(Duration::from_millis(250));

    // Get threshold receivers with a debounce time of 10 seconds (10000ms).
    lrf.set_debounce_period(10000);

    let distance_reached_receiver = lrf.get_distance_reached_callback_receiver();

    // Spawn thread to handle received callback messages.
    // This thread ends when the `lrf` object
    // is dropped, so there is no need for manual cleanup.
    thread::spawn(move || {
        for distance_reached in distance_reached_receiver {
            println!("Distance: {} cm", distance_reached);
        }
    });

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

    println!("Press enter to exit.");
    let mut _input = String::new();
    io::stdin().read_line(&mut _input)?;
    lrf.disable_laser(); // Turn laser off
    ipcon.disconnect();
    Ok(())
}

API

To allow non-blocking usage, nearly every function of the Rust bindings returns a wrapper around a mpsc::Receiver. To block until the function has finished and get your result, call one of the receiver's recv variants. Those return either the result sent by the device, or any error occured.

Functions returning a result directly will block until the device has finished processing the request.

All functions listed below are thread-safe, those which return a receiver are lock-free.

Basic Functions

pub fn LaserRangeFinderBricklet::new(uid: &str, ip_connection: &IpConnection) → LaserRangeFinderBricklet

Creates a new LaserRangeFinderBricklet object with the unique device ID uid and adds it to the IPConnection ipcon:

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

pub fn LaserRangeFinderBricklet::get_distance(&self) → ConvertingReceiver<u16>

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

Sensor hardware version 1 (see LaserRangeFinderBricklet::get_sensor_hardware_version) cannot measure distance and velocity at the same time. Therefore, the distance mode has to be enabled using LaserRangeFinderBricklet::set_mode. Sensor hardware version 3 can measure distance and velocity at the same time. Also the laser has to be enabled, see LaserRangeFinderBricklet::enable_laser.

If you want to get the distance periodically, it is recommended to use the LaserRangeFinderBricklet::get_distance_callback_receiver callback and set the period with LaserRangeFinderBricklet::set_distance_callback_period.

pub fn LaserRangeFinderBricklet::get_velocity(&self) → ConvertingReceiver<i16>

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 LaserRangeFinderBricklet::get_sensor_hardware_version) cannot measure distance and velocity at the same time. Therefore, the velocity mode has to be enabled using LaserRangeFinderBricklet::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 LaserRangeFinderBricklet::set_configuration) is configured. Also the laser has to be enabled, see LaserRangeFinderBricklet::enable_laser.

If you want to get the velocity periodically, it is recommended to use the LaserRangeFinderBricklet::get_velocity_callback_receiver callback and set the period with LaserRangeFinderBricklet::set_velocity_callback_period.

pub fn LaserRangeFinderBricklet::set_mode(&self, mode: u8) → ConvertingReceiver<()>

Note

This function is only available if you have a LIDAR-Lite sensor with hardware version 1. Use LaserRangeFinderBricklet::set_configuration for hardware version 3. You can check the sensor hardware version using LaserRangeFinderBricklet::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 constants are available for this function:

  • LASER_RANGE_FINDER_BRICKLET_MODE_DISTANCE = 0
  • LASER_RANGE_FINDER_BRICKLET_MODE_VELOCITY_MAX_13MS = 1
  • LASER_RANGE_FINDER_BRICKLET_MODE_VELOCITY_MAX_32MS = 2
  • LASER_RANGE_FINDER_BRICKLET_MODE_VELOCITY_MAX_64MS = 3
  • LASER_RANGE_FINDER_BRICKLET_MODE_VELOCITY_MAX_127MS = 4
pub fn LaserRangeFinderBricklet::get_mode(&self) → ConvertingReceiver<u8>

Returns the mode as set by LaserRangeFinderBricklet::set_mode.

The following constants are available for this function:

  • LASER_RANGE_FINDER_BRICKLET_MODE_DISTANCE = 0
  • LASER_RANGE_FINDER_BRICKLET_MODE_VELOCITY_MAX_13MS = 1
  • LASER_RANGE_FINDER_BRICKLET_MODE_VELOCITY_MAX_32MS = 2
  • LASER_RANGE_FINDER_BRICKLET_MODE_VELOCITY_MAX_64MS = 3
  • LASER_RANGE_FINDER_BRICKLET_MODE_VELOCITY_MAX_127MS = 4
pub fn LaserRangeFinderBricklet::enable_laser(&self) → ConvertingReceiver<()>

Activates the laser of the LIDAR.

We recommend that you wait 250ms after enabling the laser before the first call of LaserRangeFinderBricklet::get_distance to ensure stable measurements.

pub fn LaserRangeFinderBricklet::disable_laser(&self) → ConvertingReceiver<()>

Deactivates the laser of the LIDAR.

pub fn LaserRangeFinderBricklet::is_laser_enabled(&self) → ConvertingReceiver<bool>

Returns true if the laser is enabled, false otherwise.

pub fn LaserRangeFinderBricklet::set_configuration(&self, acquisition_count: u8, enable_quick_termination: bool, threshold_value: u8, measurement_frequency: u16) → ConvertingReceiver<()>

Note

This function is only available if you have a LIDAR-Lite sensor with hardware version 3. Use LaserRangeFinderBricklet::set_mode for hardware version 1. You can check the sensor hardware version using LaserRangeFinderBricklet::get_sensor_hardware_version.

The Acquisition 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).

pub fn LaserRangeFinderBricklet::get_configuration(&self) → ConvertingReceiver<Configuration>

Returns the configuration as set by LaserRangeFinderBricklet::set_configuration.

New in version 2.0.3 (Plugin).

Advanced Functions

pub fn LaserRangeFinderBricklet::set_moving_average(&self, distance_average_length: u8, velocity_average_length: u8) → ConvertingReceiver<()>

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.

pub fn LaserRangeFinderBricklet::get_moving_average(&self) → ConvertingReceiver<MovingAverage>

Returns the length moving average as set by LaserRangeFinderBricklet::set_moving_average.

pub fn LaserRangeFinderBricklet::get_sensor_hardware_version(&self) → ConvertingReceiver<u8>

Returns the LIDAR-Lite hardware version.

The following constants are available for this function:

  • LASER_RANGE_FINDER_BRICKLET_VERSION_1 = 1
  • LASER_RANGE_FINDER_BRICKLET_VERSION_3 = 3

New in version 2.0.3 (Plugin).

pub fn LaserRangeFinderBricklet::get_api_version(&self) → [u8; 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.

pub fn LaserRangeFinderBricklet::get_response_expected(&mut self, function_id: u8) → bool

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 LaserRangeFinderBricklet::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 LaserRangeFinderBricklet::set_response_expected for the list of function ID constants available for this function.

pub fn LaserRangeFinderBricklet::set_response_expected(&mut self, function_id: u8, response_expected: bool) → ()

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 constants are available for this function:

  • LASER_RANGE_FINDER_BRICKLET_FUNCTION_SET_DISTANCE_CALLBACK_PERIOD = 3
  • LASER_RANGE_FINDER_BRICKLET_FUNCTION_SET_VELOCITY_CALLBACK_PERIOD = 5
  • LASER_RANGE_FINDER_BRICKLET_FUNCTION_SET_DISTANCE_CALLBACK_THRESHOLD = 7
  • LASER_RANGE_FINDER_BRICKLET_FUNCTION_SET_VELOCITY_CALLBACK_THRESHOLD = 9
  • LASER_RANGE_FINDER_BRICKLET_FUNCTION_SET_DEBOUNCE_PERIOD = 11
  • LASER_RANGE_FINDER_BRICKLET_FUNCTION_SET_MOVING_AVERAGE = 13
  • LASER_RANGE_FINDER_BRICKLET_FUNCTION_SET_MODE = 15
  • LASER_RANGE_FINDER_BRICKLET_FUNCTION_ENABLE_LASER = 17
  • LASER_RANGE_FINDER_BRICKLET_FUNCTION_DISABLE_LASER = 18
  • LASER_RANGE_FINDER_BRICKLET_FUNCTION_SET_CONFIGURATION = 25
pub fn LaserRangeFinderBricklet::set_response_expected_all(&mut self, response_expected: bool) → ()

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

pub fn LaserRangeFinderBricklet::get_identity(&self) → ConvertingReceiver<Identity>

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

pub fn LaserRangeFinderBricklet::set_distance_callback_period(&self, period: u32) → ConvertingReceiver<()>

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

The LaserRangeFinderBricklet::get_distance_callback_receiver callback is only triggered if the distance value has changed since the last triggering.

The default value is 0.

pub fn LaserRangeFinderBricklet::get_distance_callback_period(&self) → ConvertingReceiver<u32>

Returns the period as set by LaserRangeFinderBricklet::set_distance_callback_period.

pub fn LaserRangeFinderBricklet::set_velocity_callback_period(&self, period: u32) → ConvertingReceiver<()>

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

The LaserRangeFinderBricklet::get_velocity_callback_receiver callback is only triggered if the velocity value has changed since the last triggering.

The default value is 0.

pub fn LaserRangeFinderBricklet::get_velocity_callback_period(&self) → ConvertingReceiver<u32>

Returns the period as set by LaserRangeFinderBricklet::set_velocity_callback_period.

pub fn LaserRangeFinderBricklet::set_distance_callback_threshold(&self, option: char, min: u16, max: u16) → ConvertingReceiver<()>

Sets the thresholds for the LaserRangeFinderBricklet::get_distance_reached_callback_receiver 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 constants are available for this function:

  • LASER_RANGE_FINDER_BRICKLET_THRESHOLD_OPTION_OFF = 'x'
  • LASER_RANGE_FINDER_BRICKLET_THRESHOLD_OPTION_OUTSIDE = 'o'
  • LASER_RANGE_FINDER_BRICKLET_THRESHOLD_OPTION_INSIDE = 'i'
  • LASER_RANGE_FINDER_BRICKLET_THRESHOLD_OPTION_SMALLER = '<'
  • LASER_RANGE_FINDER_BRICKLET_THRESHOLD_OPTION_GREATER = '>'
pub fn LaserRangeFinderBricklet::get_distance_callback_threshold(&self) → ConvertingReceiver<DistanceCallbackThreshold>

Returns the threshold as set by LaserRangeFinderBricklet::set_distance_callback_threshold.

The following constants are available for this function:

  • LASER_RANGE_FINDER_BRICKLET_THRESHOLD_OPTION_OFF = 'x'
  • LASER_RANGE_FINDER_BRICKLET_THRESHOLD_OPTION_OUTSIDE = 'o'
  • LASER_RANGE_FINDER_BRICKLET_THRESHOLD_OPTION_INSIDE = 'i'
  • LASER_RANGE_FINDER_BRICKLET_THRESHOLD_OPTION_SMALLER = '<'
  • LASER_RANGE_FINDER_BRICKLET_THRESHOLD_OPTION_GREATER = '>'
pub fn LaserRangeFinderBricklet::set_velocity_callback_threshold(&self, option: char, min: i16, max: i16) → ConvertingReceiver<()>

Sets the thresholds for the LaserRangeFinderBricklet::get_velocity_reached_callback_receiver 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 constants are available for this function:

  • LASER_RANGE_FINDER_BRICKLET_THRESHOLD_OPTION_OFF = 'x'
  • LASER_RANGE_FINDER_BRICKLET_THRESHOLD_OPTION_OUTSIDE = 'o'
  • LASER_RANGE_FINDER_BRICKLET_THRESHOLD_OPTION_INSIDE = 'i'
  • LASER_RANGE_FINDER_BRICKLET_THRESHOLD_OPTION_SMALLER = '<'
  • LASER_RANGE_FINDER_BRICKLET_THRESHOLD_OPTION_GREATER = '>'
pub fn LaserRangeFinderBricklet::get_velocity_callback_threshold(&self) → ConvertingReceiver<VelocityCallbackThreshold>

Returns the threshold as set by LaserRangeFinderBricklet::set_velocity_callback_threshold.

The following constants are available for this function:

  • LASER_RANGE_FINDER_BRICKLET_THRESHOLD_OPTION_OFF = 'x'
  • LASER_RANGE_FINDER_BRICKLET_THRESHOLD_OPTION_OUTSIDE = 'o'
  • LASER_RANGE_FINDER_BRICKLET_THRESHOLD_OPTION_INSIDE = 'i'
  • LASER_RANGE_FINDER_BRICKLET_THRESHOLD_OPTION_SMALLER = '<'
  • LASER_RANGE_FINDER_BRICKLET_THRESHOLD_OPTION_GREATER = '>'
pub fn LaserRangeFinderBricklet::set_debounce_period(&self, debounce: u32) → ConvertingReceiver<()>

Sets the period in ms with which the threshold callbacks

are triggered, if the thresholds

keep being reached.

The default value is 100.

pub fn LaserRangeFinderBricklet::get_debounce_period(&self) → ConvertingReceiver<u32>

Returns the debounce period as set by LaserRangeFinderBricklet::set_debounce_period.

Callbacks

Callbacks can be registered to receive time critical or recurring data from the device. The registration is done with the corresponding get_*_callback_receiver function, which returns a receiver for callback events.

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.

pub fn LaserRangeFinderBricklet::get_distance_callback_receiver(&self) → ConvertingCallbackReceiver<u16>

Receivers created with this function receive Distance events.

This callback is triggered periodically with the period that is set by LaserRangeFinderBricklet::set_distance_callback_period. The received variable is the distance value of the sensor.

The LaserRangeFinderBricklet::get_distance_callback_receiver callback is only triggered if the distance value has changed since the last triggering.

pub fn LaserRangeFinderBricklet::get_velocity_callback_receiver(&self) → ConvertingCallbackReceiver<i16>

Receivers created with this function receive Velocity events.

This callback is triggered periodically with the period that is set by LaserRangeFinderBricklet::set_velocity_callback_period. The received variable is the velocity value of the sensor.

The LaserRangeFinderBricklet::get_velocity_callback_receiver callback is only triggered if the velocity has changed since the last triggering.

pub fn LaserRangeFinderBricklet::get_distance_reached_callback_receiver(&self) → ConvertingCallbackReceiver<u16>

Receivers created with this function receive Distance Reached events.

This callback is triggered when the threshold as set by LaserRangeFinderBricklet::set_distance_callback_threshold is reached. The received variable is the distance value of the sensor.

If the threshold keeps being reached, the callback is triggered periodically with the period as set by LaserRangeFinderBricklet::set_debounce_period.

pub fn LaserRangeFinderBricklet::get_velocity_reached_callback_receiver(&self) → ConvertingCallbackReceiver<i16>

Receivers created with this function receive Velocity Reached events.

This callback is triggered when the threshold as set by LaserRangeFinderBricklet::set_velocity_callback_threshold is reached. The received variable is the velocity value of the sensor.

If the threshold keeps being reached, the callback is triggered periodically with the period as set by LaserRangeFinderBricklet::set_debounce_period.

Constants

LaserRangeFinderBricklet::DEVICE_IDENTIFIER

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

The LaserRangeFinderBricklet::get_identity function and the IpConnection::get_enumerate_callback_receiver callback of the IP Connection have a device_identifier parameter to specify the Brick's or Bricklet's type.

LaserRangeFinderBricklet::DEVICE_DISPLAY_NAME

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