projects / linux-block.git / blame
| Commit | Line | Data |
|---|---|---|
| 130476ac AM |
1 | .. SPDX-License-Identifier: GPL-2.0 |
| 2 | ||
| 3 | ============================== | |
| 4 | BNO055 driver | |
| 5 | ============================== | |
| 6 | ||
| 7 | 1. Overview | |
| 8 | =========== | |
| 9 | ||
| 10 | This driver supports Bosch BNO055 IMUs (on both serial and I2C busses). | |
| 11 | ||
| 12 | Accelerometer, magnetometer and gyroscope measures are always provided. | |
| 13 | When "fusion_enable" sysfs attribute is set to 1, orientation (both Euler | |
| 14 | angles and quaternion), linear velocity and gravity vector are also | |
| 15 | provided, but some sensor settings (e.g. low pass filtering and range) | |
| 16 | became locked (the IMU firmware controls them). | |
| 17 | ||
| 18 | This driver supports also IIO buffers. | |
| 19 | ||
| 20 | 2. Calibration | |
| 21 | ============== | |
| 22 | ||
| 23 | The IMU continuously performs an autocalibration procedure if (and only if) | |
| 24 | operating in fusion mode. The magnetometer autocalibration can however be | |
| 25 | disabled writing 0 in the sysfs in_magn_calibration_fast_enable attribute. | |
| 26 | ||
| 27 | The driver provides access to autocalibration flags (i.e. you can known if | |
| 28 | the IMU has successfully autocalibrated) and to the calibration data blob. | |
| 29 | ||
| 30 | The user can save this blob in a firmware file (i.e. in /lib/firmware) that | |
| 31 | the driver looks for at probe time. If found, then the IMU is initialized | |
| 32 | with this calibration data. This saves the user from performing the | |
| 33 | calibration procedure every time (which consist of moving the IMU in | |
| 34 | various way). | |
| 35 | ||
| 36 | The driver looks for calibration data file using two different names: first | |
| 37 | a file whose name is suffixed with the IMU unique ID (exposed in sysfs as | |
| 38 | serial_number) is searched for; this is useful when there is more than one | |
| 39 | IMU instance. If this file is not found, then a "generic" calibration file | |
| 40 | is searched for (which can be used when only one IMU is present, without | |
| 41 | struggling with fancy names, that change on each device). | |
| 42 | ||
| 43 | Valid calibration file names would be e.g. | |
| 44 | bno055-caldata-0e7c26a33541515120204a35342b04ff.dat | |
| 45 | bno055-caldata.dat | |
| 46 | ||
| 47 | In non-fusion mode the IIO 'offset' attributes provide access to the | |
| 48 | offsets from calibration data (if any), so that the user can apply them to | |
| 49 | the accel, angvel and magn IIO attributes. In fusion mode they are not | |
| 50 | needed (the IMU firmware internally applies those corrections) and they | |
| 51 | read as zero. |