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[2.229.210.222]) by smtp.gmail.com with ESMTPSA id i26-20020a50d75a000000b0041e84bb406fsm2704715edj.0.2022.04.15.06.00.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 15 Apr 2022 06:00:37 -0700 (PDT) From: Andrea Merello To: jic23@kernel.org, mchehab+huawei@kernel.org, linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org Cc: lars@metafoo.de, robh+dt@kernel.org, andy.shevchenko@gmail.com, matt.ranostay@konsulko.com, ardeleanalex@gmail.com, jacopo@jmondi.org, Andrea Merello Subject: [v4 14/14] docs: iio: add documentation for BNO055 driver Date: Fri, 15 Apr 2022 15:00:05 +0200 Message-Id: <20220415130005.85879-15-andrea.merello@gmail.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220415130005.85879-1-andrea.merello@gmail.com> References: <20220415130005.85879-1-andrea.merello@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Andrea Merello The bno055 driver is rather complex and have some oddities and not-obvious things that worth to document (e.g. calibration files) Signed-off-by: Andrea Merello --- Documentation/iio/bno055.rst | 50 ++++++++++++++++++++++++++++++++++++ Documentation/iio/index.rst | 2 ++ 2 files changed, 52 insertions(+) create mode 100644 Documentation/iio/bno055.rst diff --git a/Documentation/iio/bno055.rst b/Documentation/iio/bno055.rst new file mode 100644 index 000000000000..af21376d7a25 --- /dev/null +++ b/Documentation/iio/bno055.rst @@ -0,0 +1,50 @@ +.. 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. diff --git a/Documentation/iio/index.rst b/Documentation/iio/index.rst index 58b7a4ebac51..1b7292c58cd0 100644 --- a/Documentation/iio/index.rst +++ b/Documentation/iio/index.rst @@ -10,3 +10,5 @@ Industrial I/O iio_configfs ep93xx_adc + + bno055 -- 2.17.1