xref: /linux/Documentation/iio/adxl380.rst (revision a6021aa24f6417416d93318bbfa022ab229c33c8) 
1.. SPDX-License-Identifier: GPL-2.0
2
3===============
4ADXL380 driver
5===============
6
7This driver supports Analog Device's ADXL380/382 on SPI/I2C bus.
8
91. Supported devices
10====================
11
12* `ADXL380 <https://www.analog.com/ADXL380>`_
13* `ADXL382 <https://www.analog.com/ADXL382>`_
14
15The ADXL380/ADXL382 is a low noise density, low power, 3-axis accelerometer with
16selectable measurement ranges. The ADXL380 supports the ±4 g, ±8 g, and ±16 g
17ranges, and the ADXL382 supports ±15 g, ±30 g, and ±60 g ranges.
18
192. Device attributes
20====================
21
22Accelerometer measurements are always provided.
23
24Temperature data are also provided. This data can be used to monitor the
25internal system temperature or to improve the temperature stability of the
26device via calibration.
27
28Each IIO device, has a device folder under ``/sys/bus/iio/devices/iio:deviceX``,
29where X is the IIO index of the device. Under these folders reside a set of
30device files, depending on the characteristics and features of the hardware
31device in questions. These files are consistently generalized and documented in
32the IIO ABI documentation.
33
34The following tables show the adxl380 related device files, found in the
35specific device folder path ``/sys/bus/iio/devices/iio:deviceX``.
36
37+---------------------------------------------------+----------------------------------------------------------+
38| 3-Axis Accelerometer related device files         | Description                                              |
39+---------------------------------------------------+----------------------------------------------------------+
40| in_accel_scale                                    | Scale for the accelerometer channels.                    |
41+---------------------------------------------------+----------------------------------------------------------+
42| in_accel_filter_high_pass_3db_frequency           | Low pass filter bandwidth.                               |
43+---------------------------------------------------+----------------------------------------------------------+
44| in_accel_filter_high_pass_3db_frequency_available | Available low pass filter bandwidth configurations.      |
45+---------------------------------------------------+----------------------------------------------------------+
46| in_accel_filter_low_pass_3db_frequency            | High pass filter bandwidth.                              |
47+---------------------------------------------------+----------------------------------------------------------+
48| in_accel_filter_low_pass_3db_frequency_available  | Available high pass filter bandwidth configurations.     |
49+---------------------------------------------------+----------------------------------------------------------+
50| in_accel_x_calibbias                              | Calibration offset for the X-axis accelerometer channel. |
51+---------------------------------------------------+----------------------------------------------------------+
52| in_accel_x_raw                                    | Raw X-axis accelerometer channel value.                  |
53+---------------------------------------------------+----------------------------------------------------------+
54| in_accel_y_calibbias                              | y-axis acceleration offset correction                    |
55+---------------------------------------------------+----------------------------------------------------------+
56| in_accel_y_raw                                    | Raw Y-axis accelerometer channel value.                  |
57+---------------------------------------------------+----------------------------------------------------------+
58| in_accel_z_calibbias                              | Calibration offset for the Z-axis accelerometer channel. |
59+---------------------------------------------------+----------------------------------------------------------+
60| in_accel_z_raw                                    | Raw Z-axis accelerometer channel value.                  |
61+---------------------------------------------------+----------------------------------------------------------+
62
63+----------------------------------+--------------------------------------------+
64| Temperature sensor related files | Description                                |
65+----------------------------------+--------------------------------------------+
66| in_temp_raw                      | Raw temperature channel value.             |
67+----------------------------------+--------------------------------------------+
68| in_temp_offset                   | Offset for the temperature sensor channel. |
69+----------------------------------+--------------------------------------------+
70| in_temp_scale                    | Scale for the temperature sensor channel.  |
71+----------------------------------+--------------------------------------------+
72
73+------------------------------+----------------------------------------------+
74| Miscellaneous device files   | Description                                  |
75+------------------------------+----------------------------------------------+
76| name                         | Name of the IIO device.                      |
77+------------------------------+----------------------------------------------+
78| sampling_frequency           | Currently selected sample rate.              |
79+------------------------------+----------------------------------------------+
80| sampling_frequency_available | Available sampling frequency configurations. |
81+------------------------------+----------------------------------------------+
82
83Channels processed values
84-------------------------
85
86A channel value can be read from its _raw attribute. The value returned is the
87raw value as reported by the devices. To get the processed value of the channel,
88apply the following formula:
89
90.. code-block:: bash
91
92        processed value = (_raw + _offset) * _scale
93
94Where _offset and _scale are device attributes. If no _offset attribute is
95present, simply assume its value is 0.
96
97The adis16475 driver offers data for 2 types of channels, the table below shows
98the measurement units for the processed value, which are defined by the IIO
99framework:
100
101+-------------------------------------+---------------------------+
102| Channel type                        | Measurement unit          |
103+-------------------------------------+---------------------------+
104| Acceleration on X, Y, and Z axis    | Meters per Second squared |
105+-------------------------------------+---------------------------+
106| Temperature                         | Millidegrees Celsius      |
107+-------------------------------------+---------------------------+
108
109Usage examples
110--------------
111
112Show device name:
113
114.. code-block:: bash
115
116	root:/sys/bus/iio/devices/iio:device0> cat name
117        adxl382
118
119Show accelerometer channels value:
120
121.. code-block:: bash
122
123        root:/sys/bus/iio/devices/iio:device0> cat in_accel_x_raw
124        -1771
125        root:/sys/bus/iio/devices/iio:device0> cat in_accel_y_raw
126        282
127        root:/sys/bus/iio/devices/iio:device0> cat in_accel_z_raw
128        -1523
129        root:/sys/bus/iio/devices/iio:device0> cat in_accel_scale
130        0.004903325
131
132- X-axis acceleration = in_accel_x_raw * in_accel_scale = −8.683788575 m/s^2
133- Y-axis acceleration = in_accel_y_raw * in_accel_scale = 1.38273765 m/s^2
134- Z-axis acceleration = in_accel_z_raw * in_accel_scale = -7.467763975 m/s^2
135
136Set calibration offset for accelerometer channels:
137
138.. code-block:: bash
139
140        root:/sys/bus/iio/devices/iio:device0> cat in_accel_x_calibbias
141        0
142
143        root:/sys/bus/iio/devices/iio:device0> echo 50 > in_accel_x_calibbias
144        root:/sys/bus/iio/devices/iio:device0> cat in_accel_x_calibbias
145        50
146
147Set sampling frequency:
148
149.. code-block:: bash
150
151	root:/sys/bus/iio/devices/iio:device0> cat sampling_frequency
152        16000
153        root:/sys/bus/iio/devices/iio:device0> cat sampling_frequency_available
154        16000 32000 64000
155
156        root:/sys/bus/iio/devices/iio:device0> echo 32000 > sampling_frequency
157        root:/sys/bus/iio/devices/iio:device0> cat sampling_frequency
158        32000
159
160Set low pass filter bandwidth for accelerometer channels:
161
162.. code-block:: bash
163
164        root:/sys/bus/iio/devices/iio:device0> cat in_accel_filter_low_pass_3db_frequency
165        32000
166        root:/sys/bus/iio/devices/iio:device0> cat in_accel_filter_low_pass_3db_frequency_available
167        32000 8000 4000 2000
168
169        root:/sys/bus/iio/devices/iio:device0> echo 2000 > in_accel_filter_low_pass_3db_frequency
170        root:/sys/bus/iio/devices/iio:device0> cat in_accel_filter_low_pass_3db_frequency
171        2000
172
1733. Device buffers
174=================
175
176This driver supports IIO buffers.
177
178All devices support retrieving the raw acceleration and temperature measurements
179using buffers.
180
181Usage examples
182--------------
183
184Select channels for buffer read:
185
186.. code-block:: bash
187
188        root:/sys/bus/iio/devices/iio:device0> echo 1 > scan_elements/in_accel_x_en
189        root:/sys/bus/iio/devices/iio:device0> echo 1 > scan_elements/in_accel_y_en
190        root:/sys/bus/iio/devices/iio:device0> echo 1 > scan_elements/in_accel_z_en
191        root:/sys/bus/iio/devices/iio:device0> echo 1 > scan_elements/in_temp_en
192
193Set the number of samples to be stored in the buffer:
194
195.. code-block:: bash
196
197        root:/sys/bus/iio/devices/iio:device0> echo 10 > buffer/length
198
199Enable buffer readings:
200
201.. code-block:: bash
202
203        root:/sys/bus/iio/devices/iio:device0> echo 1 > buffer/enable
204
205Obtain buffered data:
206
207.. code-block:: bash
208
209        root:/sys/bus/iio/devices/iio:device0> hexdump -C /dev/iio\:device0
210        ...
211        002bc300  f7 e7 00 a8 fb c5 24 80  f7 e7 01 04 fb d6 24 80  |......$.......$.|
212        002bc310  f7 f9 00 ab fb dc 24 80  f7 c3 00 b8 fb e2 24 80  |......$.......$.|
213        002bc320  f7 fb 00 bb fb d1 24 80  f7 b1 00 5f fb d1 24 80  |......$...._..$.|
214        002bc330  f7 c4 00 c6 fb a6 24 80  f7 a6 00 68 fb f1 24 80  |......$....h..$.|
215        002bc340  f7 b8 00 a3 fb e7 24 80  f7 9a 00 b1 fb af 24 80  |......$.......$.|
216        002bc350  f7 b1 00 67 fb ee 24 80  f7 96 00 be fb 92 24 80  |...g..$.......$.|
217        002bc360  f7 ab 00 7a fc 1b 24 80  f7 b6 00 ae fb 76 24 80  |...z..$......v$.|
218        002bc370  f7 ce 00 a3 fc 02 24 80  f7 c0 00 be fb 8b 24 80  |......$.......$.|
219        002bc380  f7 c3 00 93 fb d0 24 80  f7 ce 00 d8 fb c8 24 80  |......$.......$.|
220        002bc390  f7 bd 00 c0 fb 82 24 80  f8 00 00 e8 fb db 24 80  |......$.......$.|
221        002bc3a0  f7 d8 00 d3 fb b4 24 80  f8 0b 00 e5 fb c3 24 80  |......$.......$.|
222        002bc3b0  f7 eb 00 c8 fb 92 24 80  f7 e7 00 ea fb cb 24 80  |......$.......$.|
223        002bc3c0  f7 fd 00 cb fb 94 24 80  f7 e3 00 f2 fb b8 24 80  |......$.......$.|
224        ...
225
226See ``Documentation/iio/iio_devbuf.rst`` for more information about how buffered
227data is structured.
228
2294. IIO Interfacing Tools
230========================
231
232See ``Documentation/iio/iio_tools.rst`` for the description of the available IIO
233interfacing tools.
234