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