C/C++ - IMU Brick 2.0

This is the description of the C/C++ API bindings for the IMU Brick 2.0. General information and technical specifications for the IMU Brick 2.0 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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#include <stdio.h>

#include "ip_connection.h"
#include "brick_imu_v2.h"

#define HOST "localhost"
#define PORT 4223
#define UID "XXYYZZ" // Change XXYYZZ to the UID of your IMU Brick 2.0

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

    // Create device object
    IMUV2 imu;
    imu_v2_create(&imu, 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

    // Get current quaternion
    int16_t w, x, y, z;
    if(imu_v2_get_quaternion(&imu, &w, &x, &y, &z) < 0) {
        fprintf(stderr, "Could not get quaternion, probably timeout\n");
        return 1;
    }

    printf("Quaternion [W]: %f\n", w/16383.0);
    printf("Quaternion [X]: %f\n", x/16383.0);
    printf("Quaternion [Y]: %f\n", y/16383.0);
    printf("Quaternion [Z]: %f\n", z/16383.0);

    printf("Press key to exit\n");
    getchar();
    imu_v2_destroy(&imu);
    ipcon_destroy(&ipcon); // Calls ipcon_disconnect internally
    return 0;
}

Callback

Download (example_callback.c)

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#include <stdio.h>

#include "ip_connection.h"
#include "brick_imu_v2.h"

#define HOST "localhost"
#define PORT 4223
#define UID "XXYYZZ" // Change XXYYZZ to the UID of your IMU Brick 2.0

// Callback function for quaternion callback
void cb_quaternion(int16_t w, int16_t x, int16_t y, int16_t z, void *user_data) {
    (void)user_data; // avoid unused parameter warning

    printf("Quaternion [W]: %f\n", w/16383.0);
    printf("Quaternion [X]: %f\n", x/16383.0);
    printf("Quaternion [Y]: %f\n", y/16383.0);
    printf("Quaternion [Z]: %f\n", z/16383.0);
    printf("\n");
}

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

    // Create device object
    IMUV2 imu;
    imu_v2_create(&imu, 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

    // Register quaternion callback to function cb_quaternion
    imu_v2_register_callback(&imu,
                             IMU_V2_CALLBACK_QUATERNION,
                             (void *)cb_quaternion,
                             NULL);

    // Set period for quaternion callback to 0.1s (100ms)
    imu_v2_set_quaternion_period(&imu, 100);

    printf("Press key to exit\n");
    getchar();
    imu_v2_destroy(&imu);
    ipcon_destroy(&ipcon); // Calls ipcon_disconnect internally
    return 0;
}

All Data

Download (example_all_data.c)

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#include <stdio.h>

#include "ip_connection.h"
#include "brick_imu_v2.h"

#define HOST "localhost"
#define PORT 4223
#define UID "XXYYZZ" // Change XXYYZZ to the UID of your IMU Brick 2.0

// Callback function for all data callback
void cb_all_data(int16_t acceleration[3], int16_t magnetic_field[3],
                 int16_t angular_velocity[3], int16_t euler_angle[3],
                 int16_t quaternion[4], int16_t linear_acceleration[3],
                 int16_t gravity_vector[3], int8_t temperature,
                 uint8_t calibration_status, void *user_data) {
    (void)user_data; // avoid unused parameter warning

    printf("Acceleration [X]: %f m/s²\n", acceleration[0]/100.0);
    printf("Acceleration [Y]: %f m/s²\n", acceleration[1]/100.0);
    printf("Acceleration [Z]: %f m/s²\n", acceleration[2]/100.0);
    printf("Magnetic Field [X]: %f µT\n", magnetic_field[0]/16.0);
    printf("Magnetic Field [Y]: %f µT\n", magnetic_field[1]/16.0);
    printf("Magnetic Field [Z]: %f µT\n", magnetic_field[2]/16.0);
    printf("Angular Velocity [X]: %f °/s\n", angular_velocity[0]/16.0);
    printf("Angular Velocity [Y]: %f °/s\n", angular_velocity[1]/16.0);
    printf("Angular Velocity [Z]: %f °/s\n", angular_velocity[2]/16.0);
    printf("Euler Angle [X]: %f °\n", euler_angle[0]/16.0);
    printf("Euler Angle [Y]: %f °\n", euler_angle[1]/16.0);
    printf("Euler Angle [Z]: %f °\n", euler_angle[2]/16.0);
    printf("Quaternion [W]: %f\n", quaternion[0]/16383.0);
    printf("Quaternion [X]: %f\n", quaternion[1]/16383.0);
    printf("Quaternion [Y]: %f\n", quaternion[2]/16383.0);
    printf("Quaternion [Z]: %f\n", quaternion[3]/16383.0);
    printf("Linear Acceleration [X]: %f m/s²\n", linear_acceleration[0]/100.0);
    printf("Linear Acceleration [Y]: %f m/s²\n", linear_acceleration[1]/100.0);
    printf("Linear Acceleration [Z]: %f m/s²\n", linear_acceleration[2]/100.0);
    printf("Gravity Vector [X]: %f m/s²\n", gravity_vector[0]/100.0);
    printf("Gravity Vector [Y]: %f m/s²\n", gravity_vector[1]/100.0);
    printf("Gravity Vector [Z]: %f m/s²\n", gravity_vector[2]/100.0);
    printf("Temperature: %d °C\n", temperature);
    printf("Calibration Status: %u\n", calibration_status);
    printf("\n");
}

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

    // Create device object
    IMUV2 imu;
    imu_v2_create(&imu, 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

    // Register all data callback to function cb_all_data
    imu_v2_register_callback(&imu,
                             IMU_V2_CALLBACK_ALL_DATA,
                             (void *)cb_all_data,
                             NULL);

    // Set period for all data callback to 0.1s (100ms)
    imu_v2_set_all_data_period(&imu, 100);

    printf("Press key to exit\n");
    getchar();
    imu_v2_destroy(&imu);
    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 imu_v2_create(IMUV2 *imu_v2, const char *uid, IPConnection *ipcon)

Creates the device object imu_v2 with the unique device ID uid and adds it to the IPConnection ipcon:

IMUV2 imu_v2;
imu_v2_create(&imu_v2, "YOUR_DEVICE_UID", &ipcon);

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

void imu_v2_destroy(IMUV2 *imu_v2)

Removes the device object imu_v2 from its IPConnection and destroys it. The device object cannot be used anymore afterwards.

int imu_v2_get_orientation(IMUV2 *imu_v2, int16_t *ret_heading, int16_t *ret_roll, int16_t *ret_pitch)

Returns the current orientation (heading, roll, pitch) of the IMU Brick as independent Euler angles in 1/16 degree. Note that Euler angles always experience a gimbal lock. We recommend that you use quaternions instead, if you need the absolute orientation.

The rotation angle has the following ranges:

  • heading: 0° to 360°
  • roll: -90° to +90°
  • pitch: -180° to +180°

If you want to get the orientation periodically, it is recommended to use the IMU_V2_CALLBACK_ORIENTATION callback and set the period with imu_v2_set_orientation_period().

int imu_v2_get_linear_acceleration(IMUV2 *imu_v2, int16_t *ret_x, int16_t *ret_y, int16_t *ret_z)

Returns the linear acceleration of the IMU Brick for the x, y and z axis in 1/100 m/s².

The linear acceleration is the acceleration in each of the three axis of the IMU Brick with the influences of gravity removed.

It is also possible to get the gravity vector with the influence of linear acceleration removed, see imu_v2_get_gravity_vector().

If you want to get the linear acceleration periodically, it is recommended to use the IMU_V2_CALLBACK_LINEAR_ACCELERATION callback and set the period with imu_v2_set_linear_acceleration_period().

int imu_v2_get_gravity_vector(IMUV2 *imu_v2, int16_t *ret_x, int16_t *ret_y, int16_t *ret_z)

Returns the current gravity vector of the IMU Brick for the x, y and z axis in 1/100 m/s².

The gravity vector is the acceleration that occurs due to gravity. Influences of additional linear acceleration are removed.

It is also possible to get the linear acceleration with the influence of gravity removed, see imu_v2_get_linear_acceleration().

If you want to get the gravity vector periodically, it is recommended to use the IMU_V2_CALLBACK_GRAVITY_VECTOR callback and set the period with imu_v2_set_gravity_vector_period().

int imu_v2_get_quaternion(IMUV2 *imu_v2, int16_t *ret_w, int16_t *ret_x, int16_t *ret_y, int16_t *ret_z)

Returns the current orientation (w, x, y, z) of the IMU Brick as quaternions.

You have to divide the returns values by 16383 (14 bit) to get the usual range of -1.0 to +1.0 for quaternions.

If you want to get the quaternions periodically, it is recommended to use the IMU_V2_CALLBACK_QUATERNION callback and set the period with imu_v2_set_quaternion_period().

int imu_v2_get_all_data(IMUV2 *imu_v2, int16_t ret_acceleration[3], int16_t ret_magnetic_field[3], int16_t ret_angular_velocity[3], int16_t ret_euler_angle[3], int16_t ret_quaternion[4], int16_t ret_linear_acceleration[3], int16_t ret_gravity_vector[3], int8_t *ret_temperature, uint8_t *ret_calibration_status)

Return all of the available data of the IMU Brick.

The calibration status consists of four pairs of two bits. Each pair of bits represents the status of the current calibration.

  • bit 0-1: Magnetometer
  • bit 2-3: Accelerometer
  • bit 4-5: Gyroscope
  • bit 6-7: System

A value of 0 means for "not calibrated" and a value of 3 means "fully calibrated". In your program you should always be able to ignore the calibration status, it is used by the calibration window of the Brick Viewer and it can be ignored after the first calibration. See the documentation in the calibration window for more information regarding the calibration of the IMU Brick.

If you want to get the data periodically, it is recommended to use the IMU_V2_CALLBACK_ALL_DATA callback and set the period with imu_v2_set_all_data_period().

int imu_v2_leds_on(IMUV2 *imu_v2)

Turns the orientation and direction LEDs of the IMU Brick on.

int imu_v2_leds_off(IMUV2 *imu_v2)

Turns the orientation and direction LEDs of the IMU Brick off.

int imu_v2_are_leds_on(IMUV2 *imu_v2, bool *ret_leds)

Returns true if the orientation and direction LEDs of the IMU Brick are on, false otherwise.

Advanced Functions

int imu_v2_get_acceleration(IMUV2 *imu_v2, int16_t *ret_x, int16_t *ret_y, int16_t *ret_z)

Returns the calibrated acceleration from the accelerometer for the x, y and z axis in 1/100 m/s².

If you want to get the acceleration periodically, it is recommended to use the IMU_V2_CALLBACK_ACCELERATION callback and set the period with imu_v2_set_acceleration_period().

int imu_v2_get_magnetic_field(IMUV2 *imu_v2, int16_t *ret_x, int16_t *ret_y, int16_t *ret_z)

Returns the calibrated magnetic field from the magnetometer for the x, y and z axis in 1/16 µT (Microtesla).

If you want to get the magnetic field periodically, it is recommended to use the IMU_V2_CALLBACK_MAGNETIC_FIELD callback and set the period with imu_v2_set_magnetic_field_period().

int imu_v2_get_angular_velocity(IMUV2 *imu_v2, int16_t *ret_x, int16_t *ret_y, int16_t *ret_z)

Returns the calibrated angular velocity from the gyroscope for the x, y and z axis in 1/16 °/s.

If you want to get the angular velocity periodically, it is recommended to use the IMU_V2_CALLBACK_ANGULAR_VELOCITY acallback nd set the period with imu_v2_set_angular_velocity_period().

int imu_v2_get_temperature(IMUV2 *imu_v2, int8_t *ret_temperature)

Returns the temperature of the IMU Brick. The temperature is given in °C. The temperature is measured in the core of the BNO055 IC, it is not the ambient temperature

int imu_v2_save_calibration(IMUV2 *imu_v2, bool *ret_calibration_done)

A call of this function saves the current calibration to be used as a starting point for the next restart of continuous calibration of the IMU Brick.

A return value of true means that the calibration could be used and false means that it could not be used (this happens if the calibration status is not "fully calibrated").

This function is used by the calibration window of the Brick Viewer, you should not need to call it in your program.

int imu_v2_set_sensor_configuration(IMUV2 *imu_v2, uint8_t magnetometer_rate, uint8_t gyroscope_range, uint8_t gyroscope_bandwidth, uint8_t accelerometer_range, uint8_t accelerometer_bandwidth)

Sets the available sensor configuration for the Magnetometer, Gyroscope and Accelerometer. The Accelerometer Range is user selectable in all fusion modes, all other configurations are auto-controlled in fusion mode.

The default values are:

  • Magnetometer Rate 20Hz
  • Gyroscope Range 2000°/s
  • Gyroscope Bandwidth 32Hz
  • Accelerometer Range +/-4G
  • Accelerometer Bandwidth 62.5Hz

The following defines are available for this function:

  • IMU_V2_MAGNETOMETER_RATE_2HZ = 0
  • IMU_V2_MAGNETOMETER_RATE_6HZ = 1
  • IMU_V2_MAGNETOMETER_RATE_8HZ = 2
  • IMU_V2_MAGNETOMETER_RATE_10HZ = 3
  • IMU_V2_MAGNETOMETER_RATE_15HZ = 4
  • IMU_V2_MAGNETOMETER_RATE_20HZ = 5
  • IMU_V2_MAGNETOMETER_RATE_25HZ = 6
  • IMU_V2_MAGNETOMETER_RATE_30HZ = 7
  • IMU_V2_GYROSCOPE_RANGE_2000DPS = 0
  • IMU_V2_GYROSCOPE_RANGE_1000DPS = 1
  • IMU_V2_GYROSCOPE_RANGE_500DPS = 2
  • IMU_V2_GYROSCOPE_RANGE_250DPS = 3
  • IMU_V2_GYROSCOPE_RANGE_125DPS = 4
  • IMU_V2_GYROSCOPE_BANDWIDTH_523HZ = 0
  • IMU_V2_GYROSCOPE_BANDWIDTH_230HZ = 1
  • IMU_V2_GYROSCOPE_BANDWIDTH_116HZ = 2
  • IMU_V2_GYROSCOPE_BANDWIDTH_47HZ = 3
  • IMU_V2_GYROSCOPE_BANDWIDTH_23HZ = 4
  • IMU_V2_GYROSCOPE_BANDWIDTH_12HZ = 5
  • IMU_V2_GYROSCOPE_BANDWIDTH_64HZ = 6
  • IMU_V2_GYROSCOPE_BANDWIDTH_32HZ = 7
  • IMU_V2_ACCELEROMETER_RANGE_2G = 0
  • IMU_V2_ACCELEROMETER_RANGE_4G = 1
  • IMU_V2_ACCELEROMETER_RANGE_8G = 2
  • IMU_V2_ACCELEROMETER_RANGE_16G = 3
  • IMU_V2_ACCELEROMETER_BANDWIDTH_7_81HZ = 0
  • IMU_V2_ACCELEROMETER_BANDWIDTH_15_63HZ = 1
  • IMU_V2_ACCELEROMETER_BANDWIDTH_31_25HZ = 2
  • IMU_V2_ACCELEROMETER_BANDWIDTH_62_5HZ = 3
  • IMU_V2_ACCELEROMETER_BANDWIDTH_125HZ = 4
  • IMU_V2_ACCELEROMETER_BANDWIDTH_250HZ = 5
  • IMU_V2_ACCELEROMETER_BANDWIDTH_500HZ = 6
  • IMU_V2_ACCELEROMETER_BANDWIDTH_1000HZ = 7

New in version 2.0.5 (Firmware).

int imu_v2_get_sensor_configuration(IMUV2 *imu_v2, uint8_t *ret_magnetometer_rate, uint8_t *ret_gyroscope_range, uint8_t *ret_gyroscope_bandwidth, uint8_t *ret_accelerometer_range, uint8_t *ret_accelerometer_bandwidth)

Returns the sensor configuration as set by imu_v2_set_sensor_configuration().

The following defines are available for this function:

  • IMU_V2_MAGNETOMETER_RATE_2HZ = 0
  • IMU_V2_MAGNETOMETER_RATE_6HZ = 1
  • IMU_V2_MAGNETOMETER_RATE_8HZ = 2
  • IMU_V2_MAGNETOMETER_RATE_10HZ = 3
  • IMU_V2_MAGNETOMETER_RATE_15HZ = 4
  • IMU_V2_MAGNETOMETER_RATE_20HZ = 5
  • IMU_V2_MAGNETOMETER_RATE_25HZ = 6
  • IMU_V2_MAGNETOMETER_RATE_30HZ = 7
  • IMU_V2_GYROSCOPE_RANGE_2000DPS = 0
  • IMU_V2_GYROSCOPE_RANGE_1000DPS = 1
  • IMU_V2_GYROSCOPE_RANGE_500DPS = 2
  • IMU_V2_GYROSCOPE_RANGE_250DPS = 3
  • IMU_V2_GYROSCOPE_RANGE_125DPS = 4
  • IMU_V2_GYROSCOPE_BANDWIDTH_523HZ = 0
  • IMU_V2_GYROSCOPE_BANDWIDTH_230HZ = 1
  • IMU_V2_GYROSCOPE_BANDWIDTH_116HZ = 2
  • IMU_V2_GYROSCOPE_BANDWIDTH_47HZ = 3
  • IMU_V2_GYROSCOPE_BANDWIDTH_23HZ = 4
  • IMU_V2_GYROSCOPE_BANDWIDTH_12HZ = 5
  • IMU_V2_GYROSCOPE_BANDWIDTH_64HZ = 6
  • IMU_V2_GYROSCOPE_BANDWIDTH_32HZ = 7
  • IMU_V2_ACCELEROMETER_RANGE_2G = 0
  • IMU_V2_ACCELEROMETER_RANGE_4G = 1
  • IMU_V2_ACCELEROMETER_RANGE_8G = 2
  • IMU_V2_ACCELEROMETER_RANGE_16G = 3
  • IMU_V2_ACCELEROMETER_BANDWIDTH_7_81HZ = 0
  • IMU_V2_ACCELEROMETER_BANDWIDTH_15_63HZ = 1
  • IMU_V2_ACCELEROMETER_BANDWIDTH_31_25HZ = 2
  • IMU_V2_ACCELEROMETER_BANDWIDTH_62_5HZ = 3
  • IMU_V2_ACCELEROMETER_BANDWIDTH_125HZ = 4
  • IMU_V2_ACCELEROMETER_BANDWIDTH_250HZ = 5
  • IMU_V2_ACCELEROMETER_BANDWIDTH_500HZ = 6
  • IMU_V2_ACCELEROMETER_BANDWIDTH_1000HZ = 7

New in version 2.0.5 (Firmware).

int imu_v2_set_sensor_fusion_mode(IMUV2 *imu_v2, uint8_t mode)

If the fusion mode is turned off, the functions imu_v2_get_acceleration(), imu_v2_get_magnetic_field() and imu_v2_get_angular_velocity() return uncalibrated and uncompensated sensor data. All other sensor data getters return no data.

Since firmware version 2.0.6 you can also use a fusion mode without magnetometer. In this mode the calculated orientation is relative (with magnetometer it is absolute with respect to the earth). However, the calculation can't be influenced by spurious magnetic fields.

Since firmware version 2.0.13 you can also use a fusion mode without fast magnetometer calibration. This mode is the same as the normal fusion mode, but the fast magnetometer calibration is turned off. So to find the orientation the first time will likely take longer, but small magnetic influences might not affect the automatic calibration as much.

By default sensor fusion is on.

The following defines are available for this function:

  • IMU_V2_SENSOR_FUSION_OFF = 0
  • IMU_V2_SENSOR_FUSION_ON = 1
  • IMU_V2_SENSOR_FUSION_ON_WITHOUT_MAGNETOMETER = 2
  • IMU_V2_SENSOR_FUSION_ON_WITHOUT_FAST_MAGNETOMETER_CALIBRATION = 3

New in version 2.0.5 (Firmware).

int imu_v2_get_sensor_fusion_mode(IMUV2 *imu_v2, uint8_t *ret_mode)

Returns the sensor fusion mode as set by imu_v2_set_sensor_fusion_mode().

The following defines are available for this function:

  • IMU_V2_SENSOR_FUSION_OFF = 0
  • IMU_V2_SENSOR_FUSION_ON = 1
  • IMU_V2_SENSOR_FUSION_ON_WITHOUT_MAGNETOMETER = 2
  • IMU_V2_SENSOR_FUSION_ON_WITHOUT_FAST_MAGNETOMETER_CALIBRATION = 3

New in version 2.0.5 (Firmware).

int imu_v2_get_api_version(IMUV2 *imu_v2, 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 imu_v2_get_response_expected(IMUV2 *imu_v2, 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 imu_v2_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 imu_v2_set_response_expected() for the list of function ID defines available for this function.

int imu_v2_set_response_expected(IMUV2 *imu_v2, 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:

  • IMU_V2_FUNCTION_LEDS_ON = 10
  • IMU_V2_FUNCTION_LEDS_OFF = 11
  • IMU_V2_FUNCTION_SET_ACCELERATION_PERIOD = 14
  • IMU_V2_FUNCTION_SET_MAGNETIC_FIELD_PERIOD = 16
  • IMU_V2_FUNCTION_SET_ANGULAR_VELOCITY_PERIOD = 18
  • IMU_V2_FUNCTION_SET_TEMPERATURE_PERIOD = 20
  • IMU_V2_FUNCTION_SET_ORIENTATION_PERIOD = 22
  • IMU_V2_FUNCTION_SET_LINEAR_ACCELERATION_PERIOD = 24
  • IMU_V2_FUNCTION_SET_GRAVITY_VECTOR_PERIOD = 26
  • IMU_V2_FUNCTION_SET_QUATERNION_PERIOD = 28
  • IMU_V2_FUNCTION_SET_ALL_DATA_PERIOD = 30
  • IMU_V2_FUNCTION_SET_SENSOR_CONFIGURATION = 41
  • IMU_V2_FUNCTION_SET_SENSOR_FUSION_MODE = 43
  • IMU_V2_FUNCTION_SET_SPITFP_BAUDRATE_CONFIG = 231
  • IMU_V2_FUNCTION_SET_SPITFP_BAUDRATE = 234
  • IMU_V2_FUNCTION_ENABLE_STATUS_LED = 238
  • IMU_V2_FUNCTION_DISABLE_STATUS_LED = 239
  • IMU_V2_FUNCTION_RESET = 243
int imu_v2_set_response_expected_all(IMUV2 *imu_v2, bool response_expected)

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

int imu_v2_set_spitfp_baudrate_config(IMUV2 *imu_v2, bool enable_dynamic_baudrate, uint32_t minimum_dynamic_baudrate)

The SPITF protocol can be used with a dynamic baudrate. If the dynamic baudrate is enabled, the Brick will try to adapt the baudrate for the communication between Bricks and Bricklets according to the amount of data that is transferred.

The baudrate will be increased exponentially if lots of data is send/received and decreased linearly if little data is send/received.

This lowers the baudrate in applications where little data is transferred (e.g. a weather station) and increases the robustness. If there is lots of data to transfer (e.g. Thermal Imaging Bricklet) it automatically increases the baudrate as needed.

In cases where some data has to transferred as fast as possible every few seconds (e.g. RS485 Bricklet with a high baudrate but small payload) you may want to turn the dynamic baudrate off to get the highest possible performance.

The maximum value of the baudrate can be set per port with the function imu_v2_set_spitfp_baudrate(). If the dynamic baudrate is disabled, the baudrate as set by imu_v2_set_spitfp_baudrate() will be used statically.

The minimum dynamic baudrate has a value range of 400000 to 2000000 baud.

By default dynamic baudrate is enabled and the minimum dynamic baudrate is 400000.

New in version 2.0.10 (Firmware).

int imu_v2_get_spitfp_baudrate_config(IMUV2 *imu_v2, bool *ret_enable_dynamic_baudrate, uint32_t *ret_minimum_dynamic_baudrate)

Returns the baudrate config, see imu_v2_set_spitfp_baudrate_config().

New in version 2.0.10 (Firmware).

int imu_v2_get_send_timeout_count(IMUV2 *imu_v2, uint8_t communication_method, uint32_t *ret_timeout_count)

Returns the timeout count for the different communication methods.

The methods 0-2 are available for all Bricks, 3-7 only for Master Bricks.

This function is mostly used for debugging during development, in normal operation the counters should nearly always stay at 0.

The following defines are available for this function:

  • IMU_V2_COMMUNICATION_METHOD_NONE = 0
  • IMU_V2_COMMUNICATION_METHOD_USB = 1
  • IMU_V2_COMMUNICATION_METHOD_SPI_STACK = 2
  • IMU_V2_COMMUNICATION_METHOD_CHIBI = 3
  • IMU_V2_COMMUNICATION_METHOD_RS485 = 4
  • IMU_V2_COMMUNICATION_METHOD_WIFI = 5
  • IMU_V2_COMMUNICATION_METHOD_ETHERNET = 6
  • IMU_V2_COMMUNICATION_METHOD_WIFI_V2 = 7

New in version 2.0.7 (Firmware).

int imu_v2_set_spitfp_baudrate(IMUV2 *imu_v2, char bricklet_port, uint32_t baudrate)

Sets the baudrate for a specific Bricklet port ('a' - 'd'). The baudrate can be in the range 400000 to 2000000.

If you want to increase the throughput of Bricklets you can increase the baudrate. If you get a high error count because of high interference (see imu_v2_get_spitfp_error_count()) you can decrease the baudrate.

If the dynamic baudrate feature is enabled, the baudrate set by this function corresponds to the maximum baudrate (see imu_v2_set_spitfp_baudrate_config()).

Regulatory testing is done with the default baudrate. If CE compatibility or similar is necessary in you applications we recommend to not change the baudrate.

The default baudrate for all ports is 1400000.

New in version 2.0.5 (Firmware).

int imu_v2_get_spitfp_baudrate(IMUV2 *imu_v2, char bricklet_port, uint32_t *ret_baudrate)

Returns the baudrate for a given Bricklet port, see imu_v2_set_spitfp_baudrate().

New in version 2.0.5 (Firmware).

int imu_v2_get_spitfp_error_count(IMUV2 *imu_v2, char bricklet_port, uint32_t *ret_error_count_ack_checksum, uint32_t *ret_error_count_message_checksum, uint32_t *ret_error_count_frame, uint32_t *ret_error_count_overflow)

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 Brick side. All Bricklets have a similar function that returns the errors on the Bricklet side.

New in version 2.0.5 (Firmware).

int imu_v2_enable_status_led(IMUV2 *imu_v2)

Enables the status LED.

The status LED is the blue LED next to the USB connector. If enabled is is on and it flickers if data is transfered. If disabled it is always off.

The default state is enabled.

int imu_v2_disable_status_led(IMUV2 *imu_v2)

Disables the status LED.

The status LED is the blue LED next to the USB connector. If enabled is is on and it flickers if data is transfered. If disabled it is always off.

The default state is enabled.

int imu_v2_is_status_led_enabled(IMUV2 *imu_v2, bool *ret_enabled)

Returns true if the status LED is enabled, false otherwise.

int imu_v2_get_protocol1_bricklet_name(IMUV2 *imu_v2, char port, uint8_t *ret_protocol_version, uint8_t ret_firmware_version[3], char ret_name[40])

Returns the firmware and protocol version and the name of the Bricklet for a given port.

This functions sole purpose is to allow automatic flashing of v1.x.y Bricklet plugins.

int imu_v2_get_chip_temperature(IMUV2 *imu_v2, int16_t *ret_temperature)

Returns the temperature in °C/10 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 an accuracy of +-15%. Practically it is only useful as an indicator for temperature changes.

int imu_v2_reset(IMUV2 *imu_v2)

Calling this function will reset the Brick. Calling this function on a Brick inside of a stack will reset the whole stack.

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

int imu_v2_get_identity(IMUV2 *imu_v2, 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 Brick is connected to, the position, the hardware and firmware version as well as the device identifier.

The position can be '0'-'8' (stack position).

The device identifier numbers can be found here. There is also a constant for the device identifier of this Brick.

Callback Configuration Functions

void imu_v2_register_callback(IMUV2 *imu_v2, 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 imu_v2_set_acceleration_period(IMUV2 *imu_v2, uint32_t period)

Sets the period in ms with which the IMU_V2_CALLBACK_ACCELERATION callback is triggered periodically. A value of 0 turns the callback off.

The default value is 0.

int imu_v2_get_acceleration_period(IMUV2 *imu_v2, uint32_t *ret_period)

Returns the period as set by imu_v2_set_acceleration_period().

int imu_v2_set_magnetic_field_period(IMUV2 *imu_v2, uint32_t period)

Sets the period in ms with which the IMU_V2_CALLBACK_MAGNETIC_FIELD callback is triggered periodically. A value of 0 turns the callback off.

int imu_v2_get_magnetic_field_period(IMUV2 *imu_v2, uint32_t *ret_period)

Returns the period as set by imu_v2_set_magnetic_field_period().

int imu_v2_set_angular_velocity_period(IMUV2 *imu_v2, uint32_t period)

Sets the period in ms with which the IMU_V2_CALLBACK_ANGULAR_VELOCITY callback is triggered periodically. A value of 0 turns the callback off.

int imu_v2_get_angular_velocity_period(IMUV2 *imu_v2, uint32_t *ret_period)

Returns the period as set by imu_v2_set_angular_velocity_period().

int imu_v2_set_temperature_period(IMUV2 *imu_v2, uint32_t period)

Sets the period in ms with which the IMU_V2_CALLBACK_TEMPERATURE callback is triggered periodically. A value of 0 turns the callback off.

int imu_v2_get_temperature_period(IMUV2 *imu_v2, uint32_t *ret_period)

Returns the period as set by imu_v2_set_temperature_period().

int imu_v2_set_orientation_period(IMUV2 *imu_v2, uint32_t period)

Sets the period in ms with which the IMU_V2_CALLBACK_ORIENTATION callback is triggered periodically. A value of 0 turns the callback off.

int imu_v2_get_orientation_period(IMUV2 *imu_v2, uint32_t *ret_period)

Returns the period as set by imu_v2_set_orientation_period().

int imu_v2_set_linear_acceleration_period(IMUV2 *imu_v2, uint32_t period)

Sets the period in ms with which the IMU_V2_CALLBACK_LINEAR_ACCELERATION callback is triggered periodically. A value of 0 turns the callback off.

int imu_v2_get_linear_acceleration_period(IMUV2 *imu_v2, uint32_t *ret_period)

Returns the period as set by imu_v2_set_linear_acceleration_period().

int imu_v2_set_gravity_vector_period(IMUV2 *imu_v2, uint32_t period)

Sets the period in ms with which the IMU_V2_CALLBACK_GRAVITY_VECTOR callback is triggered periodically. A value of 0 turns the callback off.

int imu_v2_get_gravity_vector_period(IMUV2 *imu_v2, uint32_t *ret_period)

Returns the period as set by imu_v2_set_gravity_vector_period().

int imu_v2_set_quaternion_period(IMUV2 *imu_v2, uint32_t period)

Sets the period in ms with which the IMU_V2_CALLBACK_QUATERNION callback is triggered periodically. A value of 0 turns the callback off.

int imu_v2_get_quaternion_period(IMUV2 *imu_v2, uint32_t *ret_period)

Returns the period as set by imu_v2_set_quaternion_period().

int imu_v2_set_all_data_period(IMUV2 *imu_v2, uint32_t period)

Sets the period in ms with which the IMU_V2_CALLBACK_ALL_DATA callback is triggered periodically. A value of 0 turns the callback off.

int imu_v2_get_all_data_period(IMUV2 *imu_v2, uint32_t *ret_period)

Returns the period as set by imu_v2_set_all_data_period().

Callbacks

Callbacks can be registered to receive time critical or recurring data from the device. The registration is done with the imu_v2_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);
}

imu_v2_register_callback(&imu_v2, IMU_V2_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.

IMU_V2_CALLBACK_ACCELERATION
void callback(int16_t x, int16_t y, int16_t z, void *user_data)

This callback is triggered periodically with the period that is set by imu_v2_set_acceleration_period(). The parameters are the acceleration for the x, y and z axis.

IMU_V2_CALLBACK_MAGNETIC_FIELD
void callback(int16_t x, int16_t y, int16_t z, void *user_data)

This callback is triggered periodically with the period that is set by imu_v2_set_magnetic_field_period(). The parameters are the magnetic field for the x, y and z axis.

IMU_V2_CALLBACK_ANGULAR_VELOCITY
void callback(int16_t x, int16_t y, int16_t z, void *user_data)

This callback is triggered periodically with the period that is set by imu_v2_set_angular_velocity_period(). The parameters are the angular velocity for the x, y and z axis.

IMU_V2_CALLBACK_TEMPERATURE
void callback(int8_t temperature, void *user_data)

This callback is triggered periodically with the period that is set by imu_v2_set_temperature_period(). The parameter is the temperature.

IMU_V2_CALLBACK_LINEAR_ACCELERATION
void callback(int16_t x, int16_t y, int16_t z, void *user_data)

This callback is triggered periodically with the period that is set by imu_v2_set_linear_acceleration_period(). The parameters are the linear acceleration for the x, y and z axis.

IMU_V2_CALLBACK_GRAVITY_VECTOR
void callback(int16_t x, int16_t y, int16_t z, void *user_data)

This callback is triggered periodically with the period that is set by imu_v2_set_gravity_vector_period(). The parameters gravity vector for the x, y and z axis.

IMU_V2_CALLBACK_ORIENTATION
void callback(int16_t heading, int16_t roll, int16_t pitch, void *user_data)

This callback is triggered periodically with the period that is set by imu_v2_set_orientation_period(). The parameters are the orientation (heading (yaw), roll, pitch) of the IMU Brick in Euler angles. See imu_v2_get_orientation() for details.

IMU_V2_CALLBACK_QUATERNION
void callback(int16_t w, int16_t x, int16_t y, int16_t z, void *user_data)

This callback is triggered periodically with the period that is set by imu_v2_set_quaternion_period(). The parameters are the orientation (x, y, z, w) of the IMU Brick in quaternions. See imu_v2_get_quaternion() for details.

IMU_V2_CALLBACK_ALL_DATA
void callback(int16_t acceleration[3], int16_t magnetic_field[3], int16_t angular_velocity[3], int16_t euler_angle[3], int16_t quaternion[4], int16_t linear_acceleration[3], int16_t gravity_vector[3], int8_t temperature, uint8_t calibration_status, void *user_data)

This callback is triggered periodically with the period that is set by imu_v2_set_all_data_period(). The parameters are as for imu_v2_get_all_data().

Constants

IMU_V2_DEVICE_IDENTIFIER

This constant is used to identify a IMU Brick 2.0.

The imu_v2_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.

IMU_V2_DEVICE_DISPLAY_NAME

This constant represents the human readable name of a IMU Brick 2.0.