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1.. SPDX-License-Identifier: GPL-2.02 3==============================4BNO055 driver5==============================6 71. Overview8===========9 10This driver supports Bosch BNO055 IMUs (on both serial and I2C busses).11 12Accelerometer, magnetometer and gyroscope measures are always provided.13When "fusion_enable" sysfs attribute is set to 1, orientation (both Euler14angles and quaternion), linear velocity and gravity vector are also15provided, but some sensor settings (e.g. low pass filtering and range)16became locked (the IMU firmware controls them).17 18This driver supports also IIO buffers.19 202. Calibration21==============22 23The IMU continuously performs an autocalibration procedure if (and only if)24operating in fusion mode. The magnetometer autocalibration can however be25disabled writing 0 in the sysfs in_magn_calibration_fast_enable attribute.26 27The driver provides access to autocalibration flags (i.e. you can known if28the IMU has successfully autocalibrated) and to the calibration data blob.29 30The user can save this blob in a firmware file (i.e. in /lib/firmware) that31the driver looks for at probe time. If found, then the IMU is initialized32with this calibration data. This saves the user from performing the33calibration procedure every time (which consist of moving the IMU in34various way).35 36The driver looks for calibration data file using two different names: first37a file whose name is suffixed with the IMU unique ID (exposed in sysfs as38serial_number) is searched for; this is useful when there is more than one39IMU instance. If this file is not found, then a "generic" calibration file40is searched for (which can be used when only one IMU is present, without41struggling with fancy names, that change on each device).42 43Valid calibration file names would be e.g.44 bno055-caldata-0e7c26a33541515120204a35342b04ff.dat45 bno055-caldata.dat46 47In non-fusion mode the IIO 'offset' attributes provide access to the48offsets from calibration data (if any), so that the user can apply them to49the accel, angvel and magn IIO attributes. In fusion mode they are not50needed (the IMU firmware internally applies those corrections) and they51read as zero.52