Rust - Hall Effect Bricklet

This is the description of the Rust API bindings for the Hall Effect Bricklet. General information and technical specifications for the Hall Effect 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::{hall_effect_bricklet::*, ip_connection::IpConnection};

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

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

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

    // Get current edge count without reset.
    let count = he.get_edge_count(false).recv()?;
    println!("Count: {}", count);

    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::{hall_effect_bricklet::*, ip_connection::IpConnection};

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

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

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

    let edge_count_receiver = he.get_edge_count_callback_receiver();

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

    // Set period for edge count receiver to 0.05s (50ms).
    // Note: The edge count callback is only called every 0.05 seconds
    //       if the edge count has changed since the last call!
    he.set_edge_count_callback_period(50);

    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 HallEffectBricklet::new(uid: &str, ip_connection: &IpConnection) → HallEffectBricklet

Creates a new HallEffectBricklet 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 HallEffectBricklet::get_value(&self) → ConvertingReceiver<bool>

Returns true if a magnetic field of 35 Gauss (3.5mT) or greater is detected.

pub fn HallEffectBricklet::get_edge_count(&self, reset_counter: bool) → ConvertingReceiver<u32>

Returns the current value of the edge counter. You can configure edge type (rising, falling, both) that is counted with HallEffectBricklet::set_edge_count_config.

If you set the reset counter to true, the count is set back to 0 directly after it is read.

Advanced Functions

pub fn HallEffectBricklet::set_edge_count_config(&self, edge_type: u8, debounce: u8) → ConvertingReceiver<()>

The edge type parameter configures if rising edges, falling edges or both are counted. Possible edge types are:

  • 0 = rising (default)
  • 1 = falling
  • 2 = both

A magnetic field of 35 Gauss (3.5mT) or greater causes a falling edge and a magnetic field of 25 Gauss (2.5mT) or smaller causes a rising edge.

If a magnet comes near the Bricklet the signal goes low (falling edge), if a magnet is removed from the vicinity the signal goes high (rising edge).

The debounce time is given in ms.

Configuring an edge counter resets its value to 0.

If you don't know what any of this means, just leave it at default. The default configuration is very likely OK for you.

Default values: 0 (edge type) and 100ms (debounce time)

The following constants are available for this function:

  • HALL_EFFECT_BRICKLET_EDGE_TYPE_RISING = 0
  • HALL_EFFECT_BRICKLET_EDGE_TYPE_FALLING = 1
  • HALL_EFFECT_BRICKLET_EDGE_TYPE_BOTH = 2
pub fn HallEffectBricklet::get_edge_count_config(&self) → ConvertingReceiver<EdgeCountConfig>

Returns the edge type and debounce time as set by HallEffectBricklet::set_edge_count_config.

The following constants are available for this function:

  • HALL_EFFECT_BRICKLET_EDGE_TYPE_RISING = 0
  • HALL_EFFECT_BRICKLET_EDGE_TYPE_FALLING = 1
  • HALL_EFFECT_BRICKLET_EDGE_TYPE_BOTH = 2
pub fn HallEffectBricklet::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 HallEffectBricklet::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 HallEffectBricklet::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 HallEffectBricklet::set_response_expected for the list of function ID constants available for this function.

pub fn HallEffectBricklet::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:

  • HALL_EFFECT_BRICKLET_FUNCTION_SET_EDGE_COUNT_CONFIG = 3
  • HALL_EFFECT_BRICKLET_FUNCTION_SET_EDGE_INTERRUPT = 5
  • HALL_EFFECT_BRICKLET_FUNCTION_SET_EDGE_COUNT_CALLBACK_PERIOD = 7
pub fn HallEffectBricklet::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 HallEffectBricklet::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 HallEffectBricklet::set_edge_interrupt(&self, edges: u32) → ConvertingReceiver<()>

Sets the number of edges until an interrupt is invoked.

If edges is set to n, an interrupt is invoked for every n-th detected edge.

If edges is set to 0, the interrupt is disabled.

Default value is 0.

pub fn HallEffectBricklet::get_edge_interrupt(&self) → ConvertingReceiver<u32>

Returns the edges as set by HallEffectBricklet::set_edge_interrupt.

pub fn HallEffectBricklet::set_edge_count_callback_period(&self, period: u32) → ConvertingReceiver<()>

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

The HallEffectBricklet::get_edge_count_callback_receiver callback is only triggered if the edge count has changed since the last triggering.

The default value is 0.

pub fn HallEffectBricklet::get_edge_count_callback_period(&self) → ConvertingReceiver<u32>

Returns the period as set by HallEffectBricklet::set_edge_count_callback_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 HallEffectBricklet::get_edge_count_callback_receiver(&self) → ConvertingCallbackReceiver<EdgeCountEvent>

Receivers created with this function receive Edge Count events.

This callback is triggered periodically with the period that is set by HallEffectBricklet::set_edge_count_callback_period. The members of the received struct are the current count and the current value (see HallEffectBricklet::get_value and HallEffectBricklet::get_edge_count).

The HallEffectBricklet::get_edge_count_callback_receiver callback is only triggered if the count or value changed since the last triggering.

Constants

HallEffectBricklet::DEVICE_IDENTIFIER

This constant is used to identify a Hall Effect Bricklet.

The HallEffectBricklet::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.

HallEffectBricklet::DEVICE_DISPLAY_NAME

This constant represents the human readable name of a Hall Effect Bricklet.