52 lines
2.1 KiB
ReStructuredText
52 lines
2.1 KiB
ReStructuredText
.. SPDX-License-Identifier: GPL-2.0
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==============================
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BNO055 driver
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==============================
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1. Overview
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===========
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This driver supports Bosch BNO055 IMUs (on both serial and I2C busses).
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Accelerometer, magnetometer and gyroscope measures are always provided.
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When "fusion_enable" sysfs attribute is set to 1, orientation (both Euler
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angles and quaternion), linear velocity and gravity vector are also
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provided, but some sensor settings (e.g. low pass filtering and range)
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became locked (the IMU firmware controls them).
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This driver supports also IIO buffers.
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2. Calibration
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==============
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The IMU continuously performs an autocalibration procedure if (and only if)
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operating in fusion mode. The magnetometer autocalibration can however be
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disabled writing 0 in the sysfs in_magn_calibration_fast_enable attribute.
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The driver provides access to autocalibration flags (i.e. you can known if
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the IMU has successfully autocalibrated) and to the calibration data blob.
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The user can save this blob in a firmware file (i.e. in /lib/firmware) that
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the driver looks for at probe time. If found, then the IMU is initialized
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with this calibration data. This saves the user from performing the
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calibration procedure every time (which consist of moving the IMU in
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various way).
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The driver looks for calibration data file using two different names: first
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a file whose name is suffixed with the IMU unique ID (exposed in sysfs as
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serial_number) is searched for; this is useful when there is more than one
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IMU instance. If this file is not found, then a "generic" calibration file
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is searched for (which can be used when only one IMU is present, without
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struggling with fancy names, that change on each device).
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Valid calibration file names would be e.g.
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bno055-caldata-0e7c26a33541515120204a35342b04ff.dat
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bno055-caldata.dat
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In non-fusion mode the IIO 'offset' attributes provide access to the
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offsets from calibration data (if any), so that the user can apply them to
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the accel, angvel and magn IIO attributes. In fusion mode they are not
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needed (the IMU firmware internally applies those corrections) and they
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read as zero.
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