Rust - Load Cell Bricklet 2.0

This is the description of the Rust API bindings for the Load Cell Bricklet 2.0. General information and technical specifications for the Load Cell Bricklet 2.0 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, load_cell_v2_bricklet::*};

const HOST: &str = "localhost";
const PORT: u16 = 4223;
const UID: &str = "XYZ"; // Change XYZ to the UID of your Load Cell Bricklet 2.0.

fn main() -> Result<(), Box<dyn Error>> {
    let ipcon = IpConnection::new(); // Create IP connection.
    let lc = LoadCellV2Bricklet::new(UID, &ipcon); // Create device object.

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

    // Get current weight.
    let weight = lc.get_weight().recv()?;
    println!("Weight: {} g", weight);

    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, load_cell_v2_bricklet::*};

const HOST: &str = "localhost";
const PORT: u16 = 4223;
const UID: &str = "XYZ"; // Change XYZ to the UID of your Load Cell Bricklet 2.0.

fn main() -> Result<(), Box<dyn Error>> {
    let ipcon = IpConnection::new(); // Create IP connection.
    let lc = LoadCellV2Bricklet::new(UID, &ipcon); // Create device object.

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

    let weight_receiver = lc.get_weight_callback_receiver();

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

    // Set period for weight callback to 1s (1000ms) without a threshold.
    lc.set_weight_callback_configuration(1000, false, 'x', 0, 0);

    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, load_cell_v2_bricklet::*};

const HOST: &str = "localhost";
const PORT: u16 = 4223;
const UID: &str = "XYZ"; // Change XYZ to the UID of your Load Cell Bricklet 2.0.

fn main() -> Result<(), Box<dyn Error>> {
    let ipcon = IpConnection::new(); // Create IP connection.
    let lc = LoadCellV2Bricklet::new(UID, &ipcon); // Create device object.

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

    let weight_receiver = lc.get_weight_callback_receiver();

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

    // Configure threshold for weight "greater than 200 g"
    // with a debounce period of 1s (1000ms).
    lc.set_weight_callback_configuration(1000, false, '>', 200, 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 LoadCellV2Bricklet::new(uid: &str, ip_connection: &IpConnection) → LoadCellV2Bricklet

Creates a new LoadCellV2Bricklet 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 LoadCellV2Bricklet::get_weight(&self) → ConvertingReceiver<i32>

Returns the currently measured weight in grams.

If you want to get the value periodically, it is recommended to use the LoadCellV2Bricklet::get_weight_callback_receiver callback. You can set the callback configuration with LoadCellV2Bricklet::set_weight_callback_configuration.

pub fn LoadCellV2Bricklet::set_info_led_config(&self, config: u8) → ConvertingReceiver<()>

Configures the info LED to be either turned off, turned on, or blink in heartbeat mode.

The following constants are available for this function:

  • LOAD_CELL_V2_BRICKLET_INFO_LED_CONFIG_OFF = 0
  • LOAD_CELL_V2_BRICKLET_INFO_LED_CONFIG_ON = 1
  • LOAD_CELL_V2_BRICKLET_INFO_LED_CONFIG_SHOW_HEARTBEAT = 2
pub fn LoadCellV2Bricklet::get_info_led_config(&self) → ConvertingReceiver<u8>

Returns the LED configuration as set by LoadCellV2Bricklet::set_info_led_config

The following constants are available for this function:

  • LOAD_CELL_V2_BRICKLET_INFO_LED_CONFIG_OFF = 0
  • LOAD_CELL_V2_BRICKLET_INFO_LED_CONFIG_ON = 1
  • LOAD_CELL_V2_BRICKLET_INFO_LED_CONFIG_SHOW_HEARTBEAT = 2
pub fn LoadCellV2Bricklet::tare(&self) → ConvertingReceiver<()>

Sets the currently measured weight as tare weight.

Advanced Functions

pub fn LoadCellV2Bricklet::set_moving_average(&self, average: u16) → ConvertingReceiver<()>

Sets the length of a moving averaging for the weight value.

Setting the length to 1 will turn the averaging off. With less averaging, there is more noise on the data.

The range for the averaging is 1-100.

The default value is 4.

pub fn LoadCellV2Bricklet::get_moving_average(&self) → ConvertingReceiver<u16>

Returns the length moving average as set by LoadCellV2Bricklet::set_moving_average.

pub fn LoadCellV2Bricklet::calibrate(&self, weight: u32) → ConvertingReceiver<()>

To calibrate your Load Cell Bricklet 2.0 you have to

  • empty the scale and call this function with 0 and
  • add a known weight to the scale and call this function with the weight in grams.

The calibration is saved in the flash of the Bricklet and only needs to be done once.

We recommend to use the Brick Viewer for calibration, you don't need to call this function in your source code.

pub fn LoadCellV2Bricklet::set_configuration(&self, rate: u8, gain: u8) → ConvertingReceiver<()>

The measurement rate and gain are configurable.

The rate can be either 10Hz or 80Hz. A faster rate will produce more noise. It is additionally possible to add a moving average (see LoadCellV2Bricklet::set_moving_average) to the measurements.

The gain can be 128x, 64x or 32x. It represents a measurement range of ±20mV, ±40mV and ±80mV respectively. The Load Cell Bricklet uses an excitation voltage of 5V and most load cells use an output of 2mV/V. That means the voltage range is ±15mV for most load cells (i.e. gain of 128x is best). If you don't know what all of this means you should keep it at 128x, it will most likely be correct.

The default rate is 10Hz and the default gain is 128x.

The following constants are available for this function:

  • LOAD_CELL_V2_BRICKLET_RATE_10HZ = 0
  • LOAD_CELL_V2_BRICKLET_RATE_80HZ = 1
  • LOAD_CELL_V2_BRICKLET_GAIN_128X = 0
  • LOAD_CELL_V2_BRICKLET_GAIN_64X = 1
  • LOAD_CELL_V2_BRICKLET_GAIN_32X = 2
pub fn LoadCellV2Bricklet::get_configuration(&self) → ConvertingReceiver<Configuration>

Returns the configuration as set by LoadCellV2Bricklet::set_configuration.

The following constants are available for this function:

  • LOAD_CELL_V2_BRICKLET_RATE_10HZ = 0
  • LOAD_CELL_V2_BRICKLET_RATE_80HZ = 1
  • LOAD_CELL_V2_BRICKLET_GAIN_128X = 0
  • LOAD_CELL_V2_BRICKLET_GAIN_64X = 1
  • LOAD_CELL_V2_BRICKLET_GAIN_32X = 2
pub fn LoadCellV2Bricklet::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 LoadCellV2Bricklet::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 LoadCellV2Bricklet::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 LoadCellV2Bricklet::set_response_expected for the list of function ID constants available for this function.

pub fn LoadCellV2Bricklet::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:

  • LOAD_CELL_V2_BRICKLET_FUNCTION_SET_WEIGHT_CALLBACK_CONFIGURATION = 2
  • LOAD_CELL_V2_BRICKLET_FUNCTION_SET_MOVING_AVERAGE = 5
  • LOAD_CELL_V2_BRICKLET_FUNCTION_SET_INFO_LED_CONFIG = 7
  • LOAD_CELL_V2_BRICKLET_FUNCTION_CALIBRATE = 9
  • LOAD_CELL_V2_BRICKLET_FUNCTION_TARE = 10
  • LOAD_CELL_V2_BRICKLET_FUNCTION_SET_CONFIGURATION = 11
  • LOAD_CELL_V2_BRICKLET_FUNCTION_SET_WRITE_FIRMWARE_POINTER = 237
  • LOAD_CELL_V2_BRICKLET_FUNCTION_SET_STATUS_LED_CONFIG = 239
  • LOAD_CELL_V2_BRICKLET_FUNCTION_RESET = 243
  • LOAD_CELL_V2_BRICKLET_FUNCTION_WRITE_UID = 248
pub fn LoadCellV2Bricklet::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 LoadCellV2Bricklet::get_spitfp_error_count(&self) → ConvertingReceiver<SpitfpErrorCount>

Returns the error count for the communication between Brick and Bricklet.

The errors are divided into

  • ACK checksum errors,
  • message checksum errors,
  • framing errors and
  • overflow errors.

The errors counts are for errors that occur on the Bricklet side. All Bricks have a similar function that returns the errors on the Brick side.

pub fn LoadCellV2Bricklet::set_bootloader_mode(&self, mode: u8) → ConvertingReceiver<u8>

Sets the bootloader mode and returns the status after the requested mode change was instigated.

You can change from bootloader mode to firmware mode and vice versa. A change from bootloader mode to firmware mode will only take place if the entry function, device identifier and CRC are present and correct.

This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.

The following constants are available for this function:

  • LOAD_CELL_V2_BRICKLET_BOOTLOADER_MODE_BOOTLOADER = 0
  • LOAD_CELL_V2_BRICKLET_BOOTLOADER_MODE_FIRMWARE = 1
  • LOAD_CELL_V2_BRICKLET_BOOTLOADER_MODE_BOOTLOADER_WAIT_FOR_REBOOT = 2
  • LOAD_CELL_V2_BRICKLET_BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_REBOOT = 3
  • LOAD_CELL_V2_BRICKLET_BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_ERASE_AND_REBOOT = 4
  • LOAD_CELL_V2_BRICKLET_BOOTLOADER_STATUS_OK = 0
  • LOAD_CELL_V2_BRICKLET_BOOTLOADER_STATUS_INVALID_MODE = 1
  • LOAD_CELL_V2_BRICKLET_BOOTLOADER_STATUS_NO_CHANGE = 2
  • LOAD_CELL_V2_BRICKLET_BOOTLOADER_STATUS_ENTRY_FUNCTION_NOT_PRESENT = 3
  • LOAD_CELL_V2_BRICKLET_BOOTLOADER_STATUS_DEVICE_IDENTIFIER_INCORRECT = 4
  • LOAD_CELL_V2_BRICKLET_BOOTLOADER_STATUS_CRC_MISMATCH = 5
pub fn LoadCellV2Bricklet::get_bootloader_mode(&self) → ConvertingReceiver<u8>

Returns the current bootloader mode, see LoadCellV2Bricklet::set_bootloader_mode.

The following constants are available for this function:

  • LOAD_CELL_V2_BRICKLET_BOOTLOADER_MODE_BOOTLOADER = 0
  • LOAD_CELL_V2_BRICKLET_BOOTLOADER_MODE_FIRMWARE = 1
  • LOAD_CELL_V2_BRICKLET_BOOTLOADER_MODE_BOOTLOADER_WAIT_FOR_REBOOT = 2
  • LOAD_CELL_V2_BRICKLET_BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_REBOOT = 3
  • LOAD_CELL_V2_BRICKLET_BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_ERASE_AND_REBOOT = 4
pub fn LoadCellV2Bricklet::set_write_firmware_pointer(&self, pointer: u32) → ConvertingReceiver<()>

Sets the firmware pointer for LoadCellV2Bricklet::write_firmware. The pointer has to be increased by chunks of size 64. The data is written to flash every 4 chunks (which equals to one page of size 256).

This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.

pub fn LoadCellV2Bricklet::write_firmware(&self, data: [u8; 64]) → ConvertingReceiver<u8>

Writes 64 Bytes of firmware at the position as written by LoadCellV2Bricklet::set_write_firmware_pointer before. The firmware is written to flash every 4 chunks.

You can only write firmware in bootloader mode.

This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.

pub fn LoadCellV2Bricklet::set_status_led_config(&self, config: u8) → ConvertingReceiver<()>

Sets the status LED configuration. By default the LED shows communication traffic between Brick and Bricklet, it flickers once for every 10 received data packets.

You can also turn the LED permanently on/off or show a heartbeat.

If the Bricklet is in bootloader mode, the LED is will show heartbeat by default.

The following constants are available for this function:

  • LOAD_CELL_V2_BRICKLET_STATUS_LED_CONFIG_OFF = 0
  • LOAD_CELL_V2_BRICKLET_STATUS_LED_CONFIG_ON = 1
  • LOAD_CELL_V2_BRICKLET_STATUS_LED_CONFIG_SHOW_HEARTBEAT = 2
  • LOAD_CELL_V2_BRICKLET_STATUS_LED_CONFIG_SHOW_STATUS = 3
pub fn LoadCellV2Bricklet::get_status_led_config(&self) → ConvertingReceiver<u8>

Returns the configuration as set by LoadCellV2Bricklet::set_status_led_config

The following constants are available for this function:

  • LOAD_CELL_V2_BRICKLET_STATUS_LED_CONFIG_OFF = 0
  • LOAD_CELL_V2_BRICKLET_STATUS_LED_CONFIG_ON = 1
  • LOAD_CELL_V2_BRICKLET_STATUS_LED_CONFIG_SHOW_HEARTBEAT = 2
  • LOAD_CELL_V2_BRICKLET_STATUS_LED_CONFIG_SHOW_STATUS = 3
pub fn LoadCellV2Bricklet::get_chip_temperature(&self) → ConvertingReceiver<i16>

Returns the temperature in °C as measured inside the microcontroller. The value returned is not the ambient temperature!

The temperature is only proportional to the real temperature and it has bad accuracy. Practically it is only useful as an indicator for temperature changes.

pub fn LoadCellV2Bricklet::reset(&self) → ConvertingReceiver<()>

Calling this function will reset the Bricklet. All configurations will be lost.

After a reset you have to create new device objects, calling functions on the existing ones will result in undefined behavior!

pub fn LoadCellV2Bricklet::write_uid(&self, uid: u32) → ConvertingReceiver<()>

Writes a new UID into flash. If you want to set a new UID you have to decode the Base58 encoded UID string into an integer first.

We recommend that you use Brick Viewer to change the UID.

pub fn LoadCellV2Bricklet::read_uid(&self) → ConvertingReceiver<u32>

Returns the current UID as an integer. Encode as Base58 to get the usual string version.

pub fn LoadCellV2Bricklet::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 LoadCellV2Bricklet::set_weight_callback_configuration(&self, period: u32, value_has_to_change: bool, option: char, min: i32, max: i32) → ConvertingReceiver<()>

The period in ms is the period with which the LoadCellV2Bricklet::get_weight_callback_receiver callback is triggered periodically. A value of 0 turns the callback off.

If the value has to change-parameter is set to true, the callback is only triggered after the value has changed. If the value didn't change within the period, the callback is triggered immediately on change.

If it is set to false, the callback is continuously triggered with the period, independent of the value.

It is furthermore possible to constrain the callback with thresholds.

The option-parameter together with min/max sets a threshold for the LoadCellV2Bricklet::get_weight_callback_receiver callback.

The following options are possible:

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

If the option is set to 'x' (threshold turned off) the callback is triggered with the fixed period.

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

The following constants are available for this function:

  • LOAD_CELL_V2_BRICKLET_THRESHOLD_OPTION_OFF = 'x'
  • LOAD_CELL_V2_BRICKLET_THRESHOLD_OPTION_OUTSIDE = 'o'
  • LOAD_CELL_V2_BRICKLET_THRESHOLD_OPTION_INSIDE = 'i'
  • LOAD_CELL_V2_BRICKLET_THRESHOLD_OPTION_SMALLER = '<'
  • LOAD_CELL_V2_BRICKLET_THRESHOLD_OPTION_GREATER = '>'
pub fn LoadCellV2Bricklet::get_weight_callback_configuration(&self) → ConvertingReceiver<WeightCallbackConfiguration>

Returns the callback configuration as set by LoadCellV2Bricklet::set_weight_callback_configuration.

The following constants are available for this function:

  • LOAD_CELL_V2_BRICKLET_THRESHOLD_OPTION_OFF = 'x'
  • LOAD_CELL_V2_BRICKLET_THRESHOLD_OPTION_OUTSIDE = 'o'
  • LOAD_CELL_V2_BRICKLET_THRESHOLD_OPTION_INSIDE = 'i'
  • LOAD_CELL_V2_BRICKLET_THRESHOLD_OPTION_SMALLER = '<'
  • LOAD_CELL_V2_BRICKLET_THRESHOLD_OPTION_GREATER = '>'

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 LoadCellV2Bricklet::get_weight_callback_receiver(&self) → ConvertingCallbackReceiver<i32>

Receivers created with this function receive Weight events.

This callback is triggered periodically according to the configuration set by LoadCellV2Bricklet::set_weight_callback_configuration.

The received variable is the same as LoadCellV2Bricklet::get_weight.

Constants

LoadCellV2Bricklet::DEVICE_IDENTIFIER

This constant is used to identify a Load Cell Bricklet 2.0.

The LoadCellV2Bricklet::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.

LoadCellV2Bricklet::DEVICE_DISPLAY_NAME

This constant represents the human readable name of a Load Cell Bricklet 2.0.