mirror of
https://github.com/torvalds/linux.git
synced 2024-11-24 21:21:41 +00:00
234 lines
11 KiB
ReStructuredText
234 lines
11 KiB
ReStructuredText
|
.. 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.
|