Rust - Line Bricklet

This is the description of the Rust API bindings for the Line Bricklet. General information and technical specifications for the Line 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};

use tinkerforge::{ip_connection::IpConnection, line_bricklet::*};

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

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

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

    // Get current reflectivity.
    let reflectivity = l.get_reflectivity().recv()?;
    println!("Reflectivity: {}", reflectivity);

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

Callback

Download (example_callback.rs)

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use std::{error::Error, io, thread};
use tinkerforge::{ip_connection::IpConnection, line_bricklet::*};

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

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

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

    let reflectivity_receiver = l.get_reflectivity_callback_receiver();

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

    // Set period for reflectivity receiver to 1s (1000ms).
    // Note: The reflectivity callback is only called every second
    //       if the reflectivity has changed since the last call!
    l.set_reflectivity_callback_period(1000);

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

Threshold

Download (example_threshold.rs)

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use std::{error::Error, io, thread};
use tinkerforge::{ip_connection::IpConnection, line_bricklet::*};

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

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

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

    // Get threshold receivers with a debounce time of 1 second (1000ms).
    l.set_debounce_period(1000);

    let reflectivity_reached_receiver = l.get_reflectivity_reached_callback_receiver();

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

    // Configure threshold for reflectivity "greater than 2000".
    l.set_reflectivity_callback_threshold('>', 2000, 0);

    println!("Press enter to exit.");
    let mut _input = String::new();
    io::stdin().read_line(&mut _input)?;
    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 LineBricklet::new(uid: &str, ip_connection: &IpConnection) → LineBricklet

Creates a new LineBricklet 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 LineBricklet::get_reflectivity(&self) → ConvertingReceiver<u16>

Returns the currently measured reflectivity. The reflectivity is a value between 0 (not reflective) and 4095 (very reflective).

Usually black has a low reflectivity while white has a high reflectivity.

If you want to get the reflectivity periodically, it is recommended to use the LineBricklet::get_reflectivity_callback_receiver callback and set the period with LineBricklet::set_reflectivity_callback_period.

Advanced Functions

pub fn LineBricklet::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 LineBricklet::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 LineBricklet::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 LineBricklet::set_response_expected for the list of function ID constants available for this function.

pub fn LineBricklet::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:

  • LINE_BRICKLET_FUNCTION_SET_REFLECTIVITY_CALLBACK_PERIOD = 2
  • LINE_BRICKLET_FUNCTION_SET_REFLECTIVITY_CALLBACK_THRESHOLD = 4
  • LINE_BRICKLET_FUNCTION_SET_DEBOUNCE_PERIOD = 6
pub fn LineBricklet::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 LineBricklet::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 LineBricklet::set_reflectivity_callback_period(&self, period: u32) → ConvertingReceiver<()>

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

The LineBricklet::get_reflectivity_callback_receiver callback is only triggered if the reflectivity has changed since the last triggering.

The default value is 0.

pub fn LineBricklet::get_reflectivity_callback_period(&self) → ConvertingReceiver<u32>

Returns the period as set by LineBricklet::set_reflectivity_callback_period.

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

Sets the thresholds for the LineBricklet::get_reflectivity_reached_callback_receiver callback.

The following options are possible:

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

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

The following constants are available for this function:

  • LINE_BRICKLET_THRESHOLD_OPTION_OFF = 'x'
  • LINE_BRICKLET_THRESHOLD_OPTION_OUTSIDE = 'o'
  • LINE_BRICKLET_THRESHOLD_OPTION_INSIDE = 'i'
  • LINE_BRICKLET_THRESHOLD_OPTION_SMALLER = '<'
  • LINE_BRICKLET_THRESHOLD_OPTION_GREATER = '>'
pub fn LineBricklet::get_reflectivity_callback_threshold(&self) → ConvertingReceiver<ReflectivityCallbackThreshold>

Returns the threshold as set by LineBricklet::set_reflectivity_callback_threshold.

The following constants are available for this function:

  • LINE_BRICKLET_THRESHOLD_OPTION_OFF = 'x'
  • LINE_BRICKLET_THRESHOLD_OPTION_OUTSIDE = 'o'
  • LINE_BRICKLET_THRESHOLD_OPTION_INSIDE = 'i'
  • LINE_BRICKLET_THRESHOLD_OPTION_SMALLER = '<'
  • LINE_BRICKLET_THRESHOLD_OPTION_GREATER = '>'
pub fn LineBricklet::set_debounce_period(&self, debounce: u32) → ConvertingReceiver<()>

Sets the period in ms with which the threshold callback

is triggered, if the threshold

keeps being reached.

The default value is 100.

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

Returns the debounce period as set by LineBricklet::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 LineBricklet::get_reflectivity_callback_receiver(&self) → ConvertingCallbackReceiver<u16>

Receivers created with this function receive Reflectivity events.

This callback is triggered periodically with the period that is set by LineBricklet::set_reflectivity_callback_period. The received variable is the reflectivity of the sensor.

The LineBricklet::get_reflectivity_callback_receiver callback is only triggered if the reflectivity has changed since the last triggering.

pub fn LineBricklet::get_reflectivity_reached_callback_receiver(&self) → ConvertingCallbackReceiver<u16>

Receivers created with this function receive Reflectivity Reached events.

This callback is triggered when the threshold as set by LineBricklet::set_reflectivity_callback_threshold is reached. The received variable is the reflectivity of the sensor.

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

Constants

LineBricklet::DEVICE_IDENTIFIER

This constant is used to identify a Line Bricklet.

The LineBricklet::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.

LineBricklet::DEVICE_DISPLAY_NAME

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