[PATCH v5 3/3] docs: iio: add documentation for adxl380 driver

Antoniu Miclaus
2024-07-08T10:42:55Z

Add documentation for adxl380 driver which describes the driver
device files and shows how the user may use the ABI for various
scenarios (configuration, measurement, etc.).

Signed-off-by: Ramona Gradinariu <ramona.gradinariu@analog.com>
Signed-off-by: Antoniu Miclaus <antoniu.miclaus@analog.com>
---
no changes in v5.
Documentation/iio/adxl380.rst | 233 ++++++++++++++++++++++++++++++++++
Documentation/iio/index.rst | 1 +
2 files changed, 234 insertions(+)
create mode 100644 Documentation/iio/adxl380.rst

diff --git a/Documentation/iio/adxl380.rst b/Documentation/iio/adxl380.rst
new file mode 100644
index 000000000000..376dee5fe1dd
--- /dev/null
+++ b/Documentation/iio/adxl380.rst
@@ -0,0 +1,233 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+===============
+ADXL380 driver
+===============
+
+This driver supports Analog Device's ADXL380/382 on SPI/I2C bus.
+
+1. Supported devices
+====================
+
+* `ADXL380 <https://www.analog.com/ADXL380>`_
+* `ADXL382 <https://www.analog.com/ADXL382>`_
+
+The ADXL380/ADXL382 is a low noise density, low power, 3-axis accelerometer with
+selectable measurement ranges. The ADXL380 supports the ±4 g, ±8 g, and ±16 g
+ranges, and the ADXL382 supports ±15 g, ±30 g, and ±60 g ranges.
+
+2. Device attributes
+====================
+
+Accelerometer measurements are always provided.
+
+Temperature data are also provided. This data can be used to monitor the
+internal system temperature or to improve the temperature stability of the
+device via calibration.
+
+Each IIO device, has a device folder under ``/sys/bus/iio/devices/iio:deviceX``,
+where X is the IIO index of the device. Under these folders reside a set of
+device files, depending on the characteristics and features of the hardware
+device in questions. These files are consistently generalized and documented in
+the IIO ABI documentation.
+
+The following tables show the adxl380 related device files, found in the
+specific device folder path ``/sys/bus/iio/devices/iio:deviceX``.
+
++---------------------------------------------------+----------------------------------------------------------+
+| 3-Axis Accelerometer related device files | Description |
++---------------------------------------------------+----------------------------------------------------------+
+| in_accel_scale | Scale for the accelerometer channels. |
++---------------------------------------------------+----------------------------------------------------------+
+| in_accel_filter_high_pass_3db_frequency | Low pass filter bandwidth. |
++---------------------------------------------------+----------------------------------------------------------+
+| in_accel_filter_high_pass_3db_frequency_available | Available low pass filter bandwidth configurations. |
++---------------------------------------------------+----------------------------------------------------------+
+| in_accel_filter_low_pass_3db_frequency | High pass filter bandwidth. |
++---------------------------------------------------+----------------------------------------------------------+
+| in_accel_filter_low_pass_3db_frequency_available | Available high pass filter bandwidth configurations. |
++---------------------------------------------------+----------------------------------------------------------+
+| in_accel_x_calibbias | Calibration offset for the X-axis accelerometer channel. |
++---------------------------------------------------+----------------------------------------------------------+
+| in_accel_x_raw | Raw X-axis accelerometer channel value. |
++---------------------------------------------------+----------------------------------------------------------+
+| in_accel_y_calibbias | y-axis acceleration offset correction |
++---------------------------------------------------+----------------------------------------------------------+
+| in_accel_y_raw | Raw Y-axis accelerometer channel value. |
++---------------------------------------------------+----------------------------------------------------------+
+| in_accel_z_calibbias | Calibration offset for the Z-axis accelerometer channel. |
++---------------------------------------------------+----------------------------------------------------------+
+| in_accel_z_raw | Raw Z-axis accelerometer channel value. |
++---------------------------------------------------+----------------------------------------------------------+
+
++----------------------------------+--------------------------------------------+
+| Temperature sensor related files | Description |
++----------------------------------+--------------------------------------------+
+| in_temp_raw | Raw temperature channel value. |
++----------------------------------+--------------------------------------------+
+| in_temp_offset | Offset for the temperature sensor channel. |
++----------------------------------+--------------------------------------------+
+| in_temp_scale | Scale for the temperature sensor channel. |
++----------------------------------+--------------------------------------------+
+
++------------------------------+----------------------------------------------+
+| Miscellaneous device files | Description |
++------------------------------+----------------------------------------------+
+| name | Name of the IIO device. |
++------------------------------+----------------------------------------------+
+| sampling_frequency | Currently selected sample rate. |
++------------------------------+----------------------------------------------+
+| sampling_frequency_available | Available sampling frequency configurations. |
++------------------------------+----------------------------------------------+
+
+Channels processed values
+-------------------------
+
+A channel value can be read from its _raw attribute. The value returned is the
+raw value as reported by the devices. To get the processed value of the channel,
+apply the following formula:
+
+.. code-block:: bash
+
+ processed value = (_raw + _offset) * _scale
+
+Where _offset and _scale are device attributes. If no _offset attribute is
+present, simply assume its value is 0.
+
+The adis16475 driver offers data for 2 types of channels, the table below shows
+the measurement units for the processed value, which are defined by the IIO
+framework:
+
++-------------------------------------+---------------------------+
+| Channel type | Measurement unit |
++-------------------------------------+---------------------------+
+| Acceleration on X, Y, and Z axis | Meters per Second squared |
++-------------------------------------+---------------------------+
+| Temperature | Millidegrees Celsius |
++-------------------------------------+---------------------------+
+
+Usage examples
+--------------
+
+Show device name:
+
+.. code-block:: bash
+
+ root:/sys/bus/iio/devices/iio:device0> cat name
+ adxl382
+
+Show accelerometer channels value:
+
+.. code-block:: bash
+
+ root:/sys/bus/iio/devices/iio:device0> cat in_accel_x_raw
+ -1771
+ root:/sys/bus/iio/devices/iio:device0> cat in_accel_y_raw
+ 282
+ root:/sys/bus/iio/devices/iio:device0> cat in_accel_z_raw
+ -1523
+ root:/sys/bus/iio/devices/iio:device0> cat in_accel_scale
+ 0.004903325
+
+- X-axis acceleration = in_accel_x_raw * in_accel_scale = −8.683788575 m/s^2
+- Y-axis acceleration = in_accel_y_raw * in_accel_scale = 1.38273765 m/s^2
+- Z-axis acceleration = in_accel_z_raw * in_accel_scale = -7.467763975 m/s^2
+
+Set calibration offset for accelerometer channels:
+
+.. code-block:: bash
+
+ root:/sys/bus/iio/devices/iio:device0> cat in_accel_x_calibbias
+ 0
+
+ root:/sys/bus/iio/devices/iio:device0> echo 50 > in_accel_x_calibbias
+ root:/sys/bus/iio/devices/iio:device0> cat in_accel_x_calibbias
+ 50
+
+Set sampling frequency:
+
+.. code-block:: bash
+
+ root:/sys/bus/iio/devices/iio:device0> cat sampling_frequency
+ 16000
+ root:/sys/bus/iio/devices/iio:device0> cat sampling_frequency_available
+ 16000 32000 64000
+
+ root:/sys/bus/iio/devices/iio:device0> echo 32000 > sampling_frequency
+ root:/sys/bus/iio/devices/iio:device0> cat sampling_frequency
+ 32000
+
+Set low pass filter bandwidth for accelerometer channels:
+
+.. code-block:: bash
+
+ root:/sys/bus/iio/devices/iio:device0> cat in_accel_filter_low_pass_3db_frequency
+ 32000
+ root:/sys/bus/iio/devices/iio:device0> cat in_accel_filter_low_pass_3db_frequency_available
+ 32000 8000 4000 2000
+
+ root:/sys/bus/iio/devices/iio:device0> echo 2000 > in_accel_filter_low_pass_3db_frequency
+ root:/sys/bus/iio/devices/iio:device0> cat in_accel_filter_low_pass_3db_frequency
+ 2000
+
+3. Device buffers
+=================
+
+This driver supports IIO buffers.
+
+All devices support retrieving the raw acceleration and temperature measurements
+using buffers.
+
+Usage examples
+--------------
+
+Select channels for buffer read:
+
+.. code-block:: bash
+
+ root:/sys/bus/iio/devices/iio:device0> echo 1 > scan_elements/in_accel_x_en
+ root:/sys/bus/iio/devices/iio:device0> echo 1 > scan_elements/in_accel_y_en
+ root:/sys/bus/iio/devices/iio:device0> echo 1 > scan_elements/in_accel_z_en
+ root:/sys/bus/iio/devices/iio:device0> echo 1 > scan_elements/in_temp_en
+
+Set the number of samples to be stored in the buffer:
+
+.. code-block:: bash
+
+ root:/sys/bus/iio/devices/iio:device0> echo 10 > buffer/length
+
+Enable buffer readings:
+
+.. code-block:: bash
+
+ root:/sys/bus/iio/devices/iio:device0> echo 1 > buffer/enable
+
+Obtain buffered data:
+
+.. code-block:: bash
+
+ root:/sys/bus/iio/devices/iio:device0> hexdump -C /dev/iio\:device0
+ ...
+ 002bc300 f7 e7 00 a8 fb c5 24 80 f7 e7 01 04 fb d6 24 80 |......$.......$.|
+ 002bc310 f7 f9 00 ab fb dc 24 80 f7 c3 00 b8 fb e2 24 80 |......$.......$.|
+ 002bc320 f7 fb 00 bb fb d1 24 80 f7 b1 00 5f fb d1 24 80 |......$...._..$.|
+ 002bc330 f7 c4 00 c6 fb a6 24 80 f7 a6 00 68 fb f1 24 80 |......$....h..$.|
+ 002bc340 f7 b8 00 a3 fb e7 24 80 f7 9a 00 b1 fb af 24 80 |......$.......$.|
+ 002bc350 f7 b1 00 67 fb ee 24 80 f7 96 00 be fb 92 24 80 |...g..$.......$.|
+ 002bc360 f7 ab 00 7a fc 1b 24 80 f7 b6 00 ae fb 76 24 80 |...z..$......v$.|
+ 002bc370 f7 ce 00 a3 fc 02 24 80 f7 c0 00 be fb 8b 24 80 |......$.......$.|
+ 002bc380 f7 c3 00 93 fb d0 24 80 f7 ce 00 d8 fb c8 24 80 |......$.......$.|
+ 002bc390 f7 bd 00 c0 fb 82 24 80 f8 00 00 e8 fb db 24 80 |......$.......$.|
+ 002bc3a0 f7 d8 00 d3 fb b4 24 80 f8 0b 00 e5 fb c3 24 80 |......$.......$.|
+ 002bc3b0 f7 eb 00 c8 fb 92 24 80 f7 e7 00 ea fb cb 24 80 |......$.......$.|
+ 002bc3c0 f7 fd 00 cb fb 94 24 80 f7 e3 00 f2 fb b8 24 80 |......$.......$.|
+ ...
+
+See ``Documentation/iio/iio_devbuf.rst`` for more information about how buffered
+data is structured.
+
+4. IIO Interfacing Tools
+========================
+
+See ``Documentation/iio/iio_tools.rst`` for the description of the available IIO
+interfacing tools.
diff --git a/Documentation/iio/index.rst b/Documentation/iio/index.rst
index 9cb4c50cb20d..e84957ccdb2e 100644
--- a/Documentation/iio/index.rst
+++ b/Documentation/iio/index.rst
@@ -21,5 +21,6 @@ Industrial I/O Kernel Drivers
ad7944
adis16475
adis16480
+ adxl380
bno055
ep93xx_adc
--
2.45.2