Python - IMU Brick

This is the description of the Python API bindings for the IMU Brick. General information and technical specifications for the IMU Brick are summarized in its hardware description.

An installation guide for the Python API bindings is part of their general description.

Examples

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

Simple

Download (example_simple.py)

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#!/usr/bin/env python
# -*- coding: utf-8 -*-

HOST = "localhost"
PORT = 4223
UID = "XXYYZZ" # Change XXYYZZ to the UID of your IMU Brick

from tinkerforge.ip_connection import IPConnection
from tinkerforge.brick_imu import BrickIMU

if __name__ == "__main__":
    ipcon = IPConnection() # Create IP connection
    imu = BrickIMU(UID, ipcon) # Create device object

    ipcon.connect(HOST, PORT) # Connect to brickd
    # Don't use device before ipcon is connected

    # Get current quaternion
    x, y, z, w = imu.get_quaternion()

    print("Quaternion [X]: " + str(x))
    print("Quaternion [Y]: " + str(y))
    print("Quaternion [Z]: " + str(z))
    print("Quaternion [W]: " + str(w))

    input("Press key to exit\n") # Use raw_input() in Python 2
    ipcon.disconnect()

Callback

Download (example_callback.py)

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#!/usr/bin/env python
# -*- coding: utf-8 -*-

HOST = "localhost"
PORT = 4223
UID = "XXYYZZ" # Change XXYYZZ to the UID of your IMU Brick

from tinkerforge.ip_connection import IPConnection
from tinkerforge.brick_imu import BrickIMU

# Callback function for quaternion callback
def cb_quaternion(x, y, z, w):
    print("Quaternion [X]: " + str(x))
    print("Quaternion [Y]: " + str(y))
    print("Quaternion [Z]: " + str(z))
    print("Quaternion [W]: " + str(w))
    print("")

if __name__ == "__main__":
    ipcon = IPConnection() # Create IP connection
    imu = BrickIMU(UID, ipcon) # Create device object

    ipcon.connect(HOST, PORT) # Connect to brickd
    # Don't use device before ipcon is connected

    # Register quaternion callback to function cb_quaternion
    imu.register_callback(imu.CALLBACK_QUATERNION, cb_quaternion)

    # Set period for quaternion callback to 1s (1000ms)
    imu.set_quaternion_period(1000)

    input("Press key to exit\n") # Use raw_input() in Python 2
    ipcon.disconnect()

API

Generally, every function of the Python bindings can throw an tinkerforge.ip_connection.Error exception that has a value and a description property. value can have different values:

  • Error.TIMEOUT = -1
  • Error.NOT_ADDED = -6 (unused since Python bindings version 2.0.0)
  • Error.ALREADY_CONNECTED = -7
  • Error.NOT_CONNECTED = -8
  • Error.INVALID_PARAMETER = -9
  • Error.NOT_SUPPORTED = -10
  • Error.UNKNOWN_ERROR_CODE = -11
  • Error.STREAM_OUT_OF_SYNC = -12
  • Error.INVALID_UID = -13
  • Error.NON_ASCII_CHAR_IN_SECRET = -14
  • Error.WRONG_DEVICE_TYPE = -15
  • Error.DEVICE_REPLACED = -16
  • Error.WRONG_RESPONSE_LENGTH = -17

All functions listed below are thread-safe.

Basic Functions

BrickIMU(uid, ipcon)
Parameters:
  • uid – Type: str
  • ipcon – Type: IPConnection
Returns:
  • imu – Type: BrickIMU

Creates an object with the unique device ID uid:

imu = BrickIMU("YOUR_DEVICE_UID", ipcon)

This object can then be used after the IP Connection is connected.

BrickIMU.get_orientation()
Return Object:
  • roll – Type: int, Unit: 1/100 °, Range: [-18000 to 18000]
  • pitch – Type: int, Unit: 1/100 °, Range: [-18000 to 18000]
  • yaw – Type: int, Unit: 1/100 °, Range: [-18000 to 18000]

Returns the current orientation (roll, pitch, yaw) of the IMU Brick as Euler angles. Note that Euler angles always experience a gimbal lock.

We recommend that you use quaternions instead.

The order to sequence in which the orientation values should be applied is roll, yaw, pitch.

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

BrickIMU.get_quaternion()
Return Object:
  • x – Type: float, Range: [-1.0 to 1.0]
  • y – Type: float, Range: [-1.0 to 1.0]
  • z – Type: float, Range: [-1.0 to 1.0]
  • w – Type: float, Range: [-1.0 to 1.0]

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

You can go from quaternions to Euler angles with the following formula:

xAngle = atan2(2*y*w - 2*x*z, 1 - 2*y*y - 2*z*z)
yAngle = atan2(2*x*w - 2*y*z, 1 - 2*x*x - 2*z*z)
zAngle =  asin(2*x*y + 2*z*w)

This process is not reversible, because of the gimbal lock.

It is also possible to calculate independent angles. You can calculate yaw, pitch and roll in a right-handed vehicle coordinate system according to DIN70000 with:

yaw   =  atan2(2*x*y + 2*w*z, w*w + x*x - y*y - z*z)
pitch = -asin(2*w*y - 2*x*z)
roll  = -atan2(2*y*z + 2*w*x, -w*w + x*x + y*y - z*z))

Converting the quaternions to an OpenGL transformation matrix is possible with the following formula:

matrix = [[1 - 2*(y*y + z*z),     2*(x*y - w*z),     2*(x*z + w*y), 0],
          [    2*(x*y + w*z), 1 - 2*(x*x + z*z),     2*(y*z - w*x), 0],
          [    2*(x*z - w*y),     2*(y*z + w*x), 1 - 2*(x*x + y*y), 0],
          [                0,                 0,                 0, 1]]

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

BrickIMU.leds_on()
Returns:
  • None

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

BrickIMU.leds_off()
Returns:
  • None

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

BrickIMU.are_leds_on()
Returns:
  • leds – Type: bool, Default: True

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

BrickIMU.set_convergence_speed(speed)
Parameters:
  • speed – Type: int, Unit: 1 °/s, Range: [0 to 216 - 1], Default: 30
Returns:
  • None

Sets the convergence speed of the IMU Brick. The convergence speed determines how the different sensor measurements are fused.

If the orientation of the IMU Brick is off by 10° and the convergence speed is set to 20°/s, it will take 0.5s until the orientation is corrected. However, if the correct orientation is reached and the convergence speed is too high, the orientation will fluctuate with the fluctuations of the accelerometer and the magnetometer.

If you set the convergence speed to 0, practically only the gyroscope is used to calculate the orientation. This gives very smooth movements, but errors of the gyroscope will not be corrected. If you set the convergence speed to something above 500, practically only the magnetometer and the accelerometer are used to calculate the orientation. In this case the movements are abrupt and the values will fluctuate, but there won't be any errors that accumulate over time.

In an application with high angular velocities, we recommend a high convergence speed, so the errors of the gyroscope can be corrected fast. In applications with only slow movements we recommend a low convergence speed. You can change the convergence speed on the fly. So it is possible (and recommended) to increase the convergence speed before an abrupt movement and decrease it afterwards again.

You might want to play around with the convergence speed in the Brick Viewer to get a feeling for a good value for your application.

BrickIMU.get_convergence_speed()
Returns:
  • speed – Type: int, Unit: 1 °/s, Range: [0 to 216 - 1], Default: 30

Returns the convergence speed as set by set_convergence_speed().

Advanced Functions

BrickIMU.get_acceleration()
Return Object:
  • x – Type: int, Unit: 1/1000 gₙ, Range: [-215 to 215 - 1]
  • y – Type: int, Unit: 1/1000 gₙ, Range: [-215 to 215 - 1]
  • z – Type: int, Unit: 1/1000 gₙ, Range: [-215 to 215 - 1]

Returns the calibrated acceleration from the accelerometer for the x, y and z axis.

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

BrickIMU.get_magnetic_field()
Return Object:
  • x – Type: int, Unit: 1/10 µT, Range: [-215 to 215 - 1]
  • y – Type: int, Unit: 1/10 µT, Range: [-215 to 215 - 1]
  • z – Type: int, Unit: 1/10 µT, Range: [-215 to 215 - 1]

Returns the calibrated magnetic field from the magnetometer for the x, y and z axis.

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

BrickIMU.get_angular_velocity()
Return Object:
  • x – Type: int, Unit: 8/115 °/s, Range: [-28750 to 28750]
  • y – Type: int, Unit: 8/115 °/s, Range: [-28750 to 28750]
  • z – Type: int, Unit: 8/115 °/s, Range: [-28750 to 28750]

Returns the calibrated angular velocity from the gyroscope for the x, y and z axis in °/14.375s (you have to divide by 14.375 to get the value in °/s).

If you want to get the angular velocity periodically, it is recommended to use the CALLBACK_ANGULAR_VELOCITY callback and set the period with set_angular_velocity_period().

BrickIMU.get_all_data()
Return Object:
  • acc_x – Type: int, Unit: 1/1000 gₙ, Range: [-215 to 215 - 1]
  • acc_y – Type: int, Unit: 1/1000 gₙ, Range: [-215 to 215 - 1]
  • acc_z – Type: int, Unit: 1/1000 gₙ, Range: [-215 to 215 - 1]
  • mag_x – Type: int, Unit: 1/10 µT, Range: [-215 to 215 - 1]
  • mag_y – Type: int, Unit: 1/10 µT, Range: [-215 to 215 - 1]
  • mag_z – Type: int, Unit: 1/10 µT, Range: [-215 to 215 - 1]
  • ang_x – Type: int, Unit: 8/115 °/s, Range: [-28750 to 28750]
  • ang_y – Type: int, Unit: 8/115 °/s, Range: [-28750 to 28750]
  • ang_z – Type: int, Unit: 8/115 °/s, Range: [-28750 to 28750]
  • temperature – Type: int, Unit: 1/100 °C, Range: [-215 to 215 - 1]

Returns the data from get_acceleration(), get_magnetic_field() and get_angular_velocity() as well as the temperature of the IMU Brick.

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

BrickIMU.get_imu_temperature()
Returns:
  • temperature – Type: int, Unit: 1/100 °C, Range: [-215 to 215 - 1]

Returns the temperature of the IMU Brick.

BrickIMU.set_acceleration_range(range)
Parameters:
  • range – Type: int, Range: [0 to 255]
Returns:
  • None

Not implemented yet.

BrickIMU.get_acceleration_range()
Returns:
  • range – Type: int, Range: [0 to 255]

Not implemented yet.

BrickIMU.set_magnetometer_range(range)
Parameters:
  • range – Type: int, Range: [0 to 255]
Returns:
  • None

Not implemented yet.

BrickIMU.get_magnetometer_range()
Returns:
  • range – Type: int, Range: [0 to 255]

Not implemented yet.

BrickIMU.set_calibration(typ, data)
Parameters:
  • typ – Type: int, Range: See constants
  • data – Type: [int, ...], Length: 10, Range: [-215 to 215 - 1]
Returns:
  • None

There are several different types that can be calibrated:

Type Description Values
0 Accelerometer Gain [mul x, mul y, mul z, div x, div y, div z, 0, 0, 0, 0]
1 Accelerometer Bias [bias x, bias y, bias z, 0, 0, 0, 0, 0, 0, 0]
2 Magnetometer Gain [mul x, mul y, mul z, div x, div y, div z, 0, 0, 0, 0]
3 Magnetometer Bias [bias x, bias y, bias z, 0, 0, 0, 0, 0, 0, 0]
4 Gyroscope Gain [mul x, mul y, mul z, div x, div y, div z, 0, 0, 0, 0]
5 Gyroscope Bias [bias xl, bias yl, bias zl, temp l, bias xh, bias yh, bias zh, temp h, 0, 0]

The calibration via gain and bias is done with the following formula:

new_value = (bias + orig_value) * gain_mul / gain_div

If you really want to write your own calibration software, please keep in mind that you first have to undo the old calibration (set bias to 0 and gain to 1/1) and that you have to average over several thousand values to obtain a usable result in the end.

The gyroscope bias is highly dependent on the temperature, so you have to calibrate the bias two times with different temperatures. The values xl, yl, zl and temp l are the bias for x, y, z and the corresponding temperature for a low temperature. The values xh, yh, zh and temp h are the same for a high temperatures. The temperature difference should be at least 5°C. If you have a temperature where the IMU Brick is mostly used, you should use this temperature for one of the sampling points.

Note

We highly recommend that you use the Brick Viewer to calibrate your IMU Brick.

The following constants are available for this function:

For typ:

  • BrickIMU.CALIBRATION_TYPE_ACCELEROMETER_GAIN = 0
  • BrickIMU.CALIBRATION_TYPE_ACCELEROMETER_BIAS = 1
  • BrickIMU.CALIBRATION_TYPE_MAGNETOMETER_GAIN = 2
  • BrickIMU.CALIBRATION_TYPE_MAGNETOMETER_BIAS = 3
  • BrickIMU.CALIBRATION_TYPE_GYROSCOPE_GAIN = 4
  • BrickIMU.CALIBRATION_TYPE_GYROSCOPE_BIAS = 5
BrickIMU.get_calibration(typ)
Parameters:
  • typ – Type: int, Range: See constants
Returns:
  • data – Type: [int, ...], Length: 10, Range: [-215 to 215 - 1]

Returns the calibration for a given type as set by set_calibration().

The following constants are available for this function:

For typ:

  • BrickIMU.CALIBRATION_TYPE_ACCELEROMETER_GAIN = 0
  • BrickIMU.CALIBRATION_TYPE_ACCELEROMETER_BIAS = 1
  • BrickIMU.CALIBRATION_TYPE_MAGNETOMETER_GAIN = 2
  • BrickIMU.CALIBRATION_TYPE_MAGNETOMETER_BIAS = 3
  • BrickIMU.CALIBRATION_TYPE_GYROSCOPE_GAIN = 4
  • BrickIMU.CALIBRATION_TYPE_GYROSCOPE_BIAS = 5
BrickIMU.orientation_calculation_on()
Returns:
  • None

Turns the orientation calculation of the IMU Brick on.

As default the calculation is on.

New in version 2.0.2 (Firmware).

BrickIMU.orientation_calculation_off()
Returns:
  • None

Turns the orientation calculation of the IMU Brick off.

If the calculation is off, get_orientation() will return the last calculated value until the calculation is turned on again.

The trigonometric functions that are needed to calculate the orientation are very expensive. We recommend to turn the orientation calculation off if the orientation is not needed, to free calculation time for the sensor fusion algorithm.

As default the calculation is on.

New in version 2.0.2 (Firmware).

BrickIMU.is_orientation_calculation_on()
Returns:
  • orientation_calculation_on – Type: bool, Default: True

Returns true if the orientation calculation of the IMU Brick is on, false otherwise.

New in version 2.0.2 (Firmware).

BrickIMU.set_spitfp_baudrate_config(enable_dynamic_baudrate, minimum_dynamic_baudrate)
Parameters:
  • enable_dynamic_baudrate – Type: bool, Default: True
  • minimum_dynamic_baudrate – Type: int, Unit: 1 Bd, Range: [400000 to 2000000], Default: 400000
Returns:
  • None

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 sent/received and decreased linearly if little data is sent/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 set_spitfp_baudrate(). If the dynamic baudrate is disabled, the baudrate as set by set_spitfp_baudrate() will be used statically.

New in version 2.3.5 (Firmware).

BrickIMU.get_spitfp_baudrate_config()
Return Object:
  • enable_dynamic_baudrate – Type: bool, Default: True
  • minimum_dynamic_baudrate – Type: int, Unit: 1 Bd, Range: [400000 to 2000000], Default: 400000

Returns the baudrate config, see set_spitfp_baudrate_config().

New in version 2.3.5 (Firmware).

BrickIMU.get_send_timeout_count(communication_method)
Parameters:
  • communication_method – Type: int, Range: See constants
Returns:
  • timeout_count – Type: int, Range: [0 to 232 - 1]

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 constants are available for this function:

For communication_method:

  • BrickIMU.COMMUNICATION_METHOD_NONE = 0
  • BrickIMU.COMMUNICATION_METHOD_USB = 1
  • BrickIMU.COMMUNICATION_METHOD_SPI_STACK = 2
  • BrickIMU.COMMUNICATION_METHOD_CHIBI = 3
  • BrickIMU.COMMUNICATION_METHOD_RS485 = 4
  • BrickIMU.COMMUNICATION_METHOD_WIFI = 5
  • BrickIMU.COMMUNICATION_METHOD_ETHERNET = 6
  • BrickIMU.COMMUNICATION_METHOD_WIFI_V2 = 7

New in version 2.3.3 (Firmware).

BrickIMU.set_spitfp_baudrate(bricklet_port, baudrate)
Parameters:
  • bricklet_port – Type: chr, Range: ["a" to "b"]
  • baudrate – Type: int, Unit: 1 Bd, Range: [400000 to 2000000], Default: 1400000
Returns:
  • None

Sets the baudrate for a specific Bricklet port.

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 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 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.

New in version 2.3.3 (Firmware).

BrickIMU.get_spitfp_baudrate(bricklet_port)
Parameters:
  • bricklet_port – Type: chr, Range: ["a" to "b"]
Returns:
  • baudrate – Type: int, Unit: 1 Bd, Range: [400000 to 2000000], Default: 1400000

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

New in version 2.3.3 (Firmware).

BrickIMU.get_spitfp_error_count(bricklet_port)
Parameters:
  • bricklet_port – Type: chr, Range: ["a" to "b"]
Return Object:
  • error_count_ack_checksum – Type: int, Range: [0 to 232 - 1]
  • error_count_message_checksum – Type: int, Range: [0 to 232 - 1]
  • error_count_frame – Type: int, Range: [0 to 232 - 1]
  • error_count_overflow – Type: int, Range: [0 to 232 - 1]

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 2.3.3 (Firmware).

BrickIMU.enable_status_led()
Returns:
  • None

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.

New in version 2.3.1 (Firmware).

BrickIMU.disable_status_led()
Returns:
  • None

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.

New in version 2.3.1 (Firmware).

BrickIMU.is_status_led_enabled()
Returns:
  • enabled – Type: bool, Default: True

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

New in version 2.3.1 (Firmware).

BrickIMU.get_chip_temperature()
Returns:
  • temperature – Type: int, Unit: 1/10 °C, Range: [-215 to 215 - 1]

Returns the temperature 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.

BrickIMU.reset()
Returns:
  • None

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!

BrickIMU.get_identity()
Return Object:
  • uid – Type: str, Length: up to 8
  • connected_uid – Type: str, Length: up to 8
  • position – Type: chr, Range: ["0" to "8"]
  • hardware_version – Type: [int, ...], Length: 3
    • 0: major – Type: int, Range: [0 to 255]
    • 1: minor – Type: int, Range: [0 to 255]
    • 2: revision – Type: int, Range: [0 to 255]
  • firmware_version – Type: [int, ...], Length: 3
    • 0: major – Type: int, Range: [0 to 255]
    • 1: minor – Type: int, Range: [0 to 255]
    • 2: revision – Type: int, Range: [0 to 255]
  • device_identifier – Type: int, Range: [0 to 216 - 1]

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 is the position in the stack from '0' (bottom) to '8' (top).

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

Callback Configuration Functions

BrickIMU.register_callback(callback_id, function)
Parameters:
  • callback_id – Type: int
  • function – Type: callable
Returns:
  • None

Registers the given function with the given callback_id.

The available callback IDs with corresponding function signatures are listed below.

BrickIMU.set_acceleration_period(period)
Parameters:
  • period – Type: int, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0
Returns:
  • None

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

BrickIMU.get_acceleration_period()
Returns:
  • period – Type: int, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0

Returns the period as set by set_acceleration_period().

BrickIMU.set_magnetic_field_period(period)
Parameters:
  • period – Type: int, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0
Returns:
  • None

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

BrickIMU.get_magnetic_field_period()
Returns:
  • period – Type: int, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0

Returns the period as set by set_magnetic_field_period().

BrickIMU.set_angular_velocity_period(period)
Parameters:
  • period – Type: int, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0
Returns:
  • None

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

BrickIMU.get_angular_velocity_period()
Returns:
  • period – Type: int, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0

Returns the period as set by set_angular_velocity_period().

BrickIMU.set_all_data_period(period)
Parameters:
  • period – Type: int, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0
Returns:
  • None

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

BrickIMU.get_all_data_period()
Returns:
  • period – Type: int, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0

Returns the period as set by set_all_data_period().

BrickIMU.set_orientation_period(period)
Parameters:
  • period – Type: int, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0
Returns:
  • None

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

BrickIMU.get_orientation_period()
Returns:
  • period – Type: int, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0

Returns the period as set by set_orientation_period().

BrickIMU.set_quaternion_period(period)
Parameters:
  • period – Type: int, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0
Returns:
  • None

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

BrickIMU.get_quaternion_period()
Returns:
  • period – Type: int, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0

Returns the period as set by set_quaternion_period().

Callbacks

Callbacks can be registered to receive time critical or recurring data from the device. The registration is done with the register_callback() function of the device object. The first parameter is the callback ID and the second parameter the callback function:

def my_callback(param):
    print(param)

imu.register_callback(BrickIMU.CALLBACK_EXAMPLE, my_callback)

The available constants with inherent number and type of parameters 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.

BrickIMU.CALLBACK_ACCELERATION
Callback Parameters:
  • x – Type: int, Unit: 1/1000 gₙ, Range: [-215 to 215 - 1]
  • y – Type: int, Unit: 1/1000 gₙ, Range: [-215 to 215 - 1]
  • z – Type: int, Unit: 1/1000 gₙ, Range: [-215 to 215 - 1]

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

BrickIMU.CALLBACK_MAGNETIC_FIELD
Callback Parameters:
  • x – Type: int, Unit: 1/10 µT, Range: [-215 to 215 - 1]
  • y – Type: int, Unit: 1/10 µT, Range: [-215 to 215 - 1]
  • z – Type: int, Unit: 1/10 µT, Range: [-215 to 215 - 1]

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

BrickIMU.CALLBACK_ANGULAR_VELOCITY
Callback Parameters:
  • x – Type: int, Unit: 8/115 °/s, Range: [-28750 to 28750]
  • y – Type: int, Unit: 8/115 °/s, Range: [-28750 to 28750]
  • z – Type: int, Unit: 8/115 °/s, Range: [-28750 to 28750]

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

BrickIMU.CALLBACK_ALL_DATA
Callback Parameters:
  • acc_x – Type: int, Unit: 1/1000 gₙ, Range: [-215 to 215 - 1]
  • acc_y – Type: int, Unit: 1/1000 gₙ, Range: [-215 to 215 - 1]
  • acc_z – Type: int, Unit: 1/1000 gₙ, Range: [-215 to 215 - 1]
  • mag_x – Type: int, Unit: 1/10 µT, Range: [-215 to 215 - 1]
  • mag_y – Type: int, Unit: 1/10 µT, Range: [-215 to 215 - 1]
  • mag_z – Type: int, Unit: 1/10 µT, Range: [-215 to 215 - 1]
  • ang_x – Type: int, Unit: 8/115 °/s, Range: [-28750 to 28750]
  • ang_y – Type: int, Unit: 8/115 °/s, Range: [-28750 to 28750]
  • ang_z – Type: int, Unit: 8/115 °/s, Range: [-28750 to 28750]
  • temperature – Type: int, Unit: 1/100 °C, Range: [-215 to 215 - 1]

This callback is triggered periodically with the period that is set by set_all_data_period(). The parameters are the acceleration, the magnetic field and the angular velocity for the x, y and z axis as well as the temperature of the IMU Brick.

BrickIMU.CALLBACK_ORIENTATION
Callback Parameters:
  • roll – Type: int, Unit: 1/100 °, Range: [-18000 to 18000]
  • pitch – Type: int, Unit: 1/100 °, Range: [-18000 to 18000]
  • yaw – Type: int, Unit: 1/100 °, Range: [-18000 to 18000]

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

BrickIMU.CALLBACK_QUATERNION
Callback Parameters:
  • x – Type: float, Range: [-1.0 to 1.0]
  • y – Type: float, Range: [-1.0 to 1.0]
  • z – Type: float, Range: [-1.0 to 1.0]
  • w – Type: float, Range: [-1.0 to 1.0]

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

Virtual Functions

Virtual functions don't communicate with the device itself, but operate only on the API bindings device object. They can be called without the corresponding IP Connection object being connected.

BrickIMU.get_api_version()
Return Object:
  • api_version – Type: [int, ...], Length: 3
    • 0: major – Type: int, Range: [0 to 255]
    • 1: minor – Type: int, Range: [0 to 255]
    • 2: revision – Type: int, Range: [0 to 255]

Returns the version of the API definition 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.

BrickIMU.get_response_expected(function_id)
Parameters:
  • function_id – Type: int, Range: See constants
Returns:
  • response_expected – Type: 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 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 sent and errors are silently ignored, because they cannot be detected.

The following constants are available for this function:

For function_id:

  • BrickIMU.FUNCTION_LEDS_ON = 8
  • BrickIMU.FUNCTION_LEDS_OFF = 9
  • BrickIMU.FUNCTION_SET_ACCELERATION_RANGE = 11
  • BrickIMU.FUNCTION_SET_MAGNETOMETER_RANGE = 13
  • BrickIMU.FUNCTION_SET_CONVERGENCE_SPEED = 15
  • BrickIMU.FUNCTION_SET_CALIBRATION = 17
  • BrickIMU.FUNCTION_SET_ACCELERATION_PERIOD = 19
  • BrickIMU.FUNCTION_SET_MAGNETIC_FIELD_PERIOD = 21
  • BrickIMU.FUNCTION_SET_ANGULAR_VELOCITY_PERIOD = 23
  • BrickIMU.FUNCTION_SET_ALL_DATA_PERIOD = 25
  • BrickIMU.FUNCTION_SET_ORIENTATION_PERIOD = 27
  • BrickIMU.FUNCTION_SET_QUATERNION_PERIOD = 29
  • BrickIMU.FUNCTION_ORIENTATION_CALCULATION_ON = 37
  • BrickIMU.FUNCTION_ORIENTATION_CALCULATION_OFF = 38
  • BrickIMU.FUNCTION_SET_SPITFP_BAUDRATE_CONFIG = 231
  • BrickIMU.FUNCTION_SET_SPITFP_BAUDRATE = 234
  • BrickIMU.FUNCTION_ENABLE_STATUS_LED = 238
  • BrickIMU.FUNCTION_DISABLE_STATUS_LED = 239
  • BrickIMU.FUNCTION_RESET = 243
  • BrickIMU.FUNCTION_WRITE_BRICKLET_PLUGIN = 246
BrickIMU.set_response_expected(function_id, response_expected)
Parameters:
  • function_id – Type: int, Range: See constants
  • response_expected – Type: bool
Returns:
  • None

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 sent and errors are silently ignored, because they cannot be detected.

The following constants are available for this function:

For function_id:

  • BrickIMU.FUNCTION_LEDS_ON = 8
  • BrickIMU.FUNCTION_LEDS_OFF = 9
  • BrickIMU.FUNCTION_SET_ACCELERATION_RANGE = 11
  • BrickIMU.FUNCTION_SET_MAGNETOMETER_RANGE = 13
  • BrickIMU.FUNCTION_SET_CONVERGENCE_SPEED = 15
  • BrickIMU.FUNCTION_SET_CALIBRATION = 17
  • BrickIMU.FUNCTION_SET_ACCELERATION_PERIOD = 19
  • BrickIMU.FUNCTION_SET_MAGNETIC_FIELD_PERIOD = 21
  • BrickIMU.FUNCTION_SET_ANGULAR_VELOCITY_PERIOD = 23
  • BrickIMU.FUNCTION_SET_ALL_DATA_PERIOD = 25
  • BrickIMU.FUNCTION_SET_ORIENTATION_PERIOD = 27
  • BrickIMU.FUNCTION_SET_QUATERNION_PERIOD = 29
  • BrickIMU.FUNCTION_ORIENTATION_CALCULATION_ON = 37
  • BrickIMU.FUNCTION_ORIENTATION_CALCULATION_OFF = 38
  • BrickIMU.FUNCTION_SET_SPITFP_BAUDRATE_CONFIG = 231
  • BrickIMU.FUNCTION_SET_SPITFP_BAUDRATE = 234
  • BrickIMU.FUNCTION_ENABLE_STATUS_LED = 238
  • BrickIMU.FUNCTION_DISABLE_STATUS_LED = 239
  • BrickIMU.FUNCTION_RESET = 243
  • BrickIMU.FUNCTION_WRITE_BRICKLET_PLUGIN = 246
BrickIMU.set_response_expected_all(response_expected)
Parameters:
  • response_expected – Type: bool
Returns:
  • None

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

Internal Functions

Internal functions are used for maintenance tasks such as flashing a new firmware of changing the UID of a Bricklet. These task should be performed using Brick Viewer instead of using the internal functions directly.

BrickIMU.get_protocol1_bricklet_name(port)
Parameters:
  • port – Type: chr, Range: ["a" to "b"]
Return Object:
  • protocol_version – Type: int, Range: [0 to 255]
  • firmware_version – Type: [int, ...], Length: 3
    • 0: major – Type: int, Range: [0 to 255]
    • 1: minor – Type: int, Range: [0 to 255]
    • 2: revision – Type: int, Range: [0 to 255]
  • name – Type: str, Length: up to 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.

BrickIMU.write_bricklet_plugin(port, offset, chunk)
Parameters:
  • port – Type: chr, Range: ["a" to "b"]
  • offset – Type: int, Range: [0 to 255]
  • chunk – Type: [int, ...], Length: 32, Range: [0 to 255]
Returns:
  • None

Writes 32 bytes of firmware to the bricklet attached at the given port. The bytes are written to the position offset * 32.

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

BrickIMU.read_bricklet_plugin(port, offset)
Parameters:
  • port – Type: chr, Range: ["a" to "b"]
  • offset – Type: int, Range: [0 to 255]
Returns:
  • chunk – Type: [int, ...], Length: 32, Range: [0 to 255]

Reads 32 bytes of firmware from the bricklet attached at the given port. The bytes are read starting at the position offset * 32.

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

Constants

BrickIMU.DEVICE_IDENTIFIER

This constant is used to identify a IMU Brick.

The get_identity() function and the IPConnection.CALLBACK_ENUMERATE callback of the IP Connection have a device_identifier parameter to specify the Brick's or Bricklet's type.

BrickIMU.DEVICE_DISPLAY_NAME

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