Documentation/iio/adxl380.rst

   1 .. SPDX-License-Identifier: GPL-2.0
   2
   3 ===============
   4 ADXL380 driver
   5 ===============
   6
   7 This driver supports Analog Device's ADXL380/382 on SPI/I2C bus.
   8
   9 1. Supported devices
  10 ====================
  11
  12 * `ADXL380 <https://www.analog.com/ADXL380>`_
  13 * `ADXL382 <https://www.analog.com/ADXL382>`_
  14
  15 The ADXL380/ADXL382 is a low noise density, low power, 3-axis accelerometer with
  16 selectable measurement ranges. The ADXL380 supports the ±4 g, ±8 g, and ±16 g
  17 ranges, and the ADXL382 supports ±15 g, ±30 g, and ±60 g ranges.
  18
  19 2. Device attributes
  20 ====================
  21
  22 Accelerometer measurements are always provided.
  23
  24 Temperature data are also provided. This data can be used to monitor the
  25 internal system temperature or to improve the temperature stability of the
  26 device via calibration.
  27
  28 Each IIO device, has a device folder under ``/sys/bus/iio/devices/iio:deviceX``,
  29 where X is the IIO index of the device. Under these folders reside a set of
  30 device files, depending on the characteristics and features of the hardware
  31 device in questions. These files are consistently generalized and documented in
  32 the IIO ABI documentation.
  33
  34 The following tables show the adxl380 related device files, found in the
  35 specific 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
  83 Channels processed values
  84 -------------------------
  85
  86 A channel value can be read from its _raw attribute. The value returned is the
  87 raw value as reported by the devices. To get the processed value of the channel,
  88 apply the following formula:
  89
  90 .. code-block:: bash
  91
  92         processed value = (_raw + _offset) * _scale
  93
  94 Where _offset and _scale are device attributes. If no _offset attribute is
  95 present, simply assume its value is 0.
  96
  97 The adis16475 driver offers data for 2 types of channels, the table below shows
  98 the measurement units for the processed value, which are defined by the IIO
  99 framework:
 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
 109 Usage examples
 110 --------------
 111
 112 Show device name:
 113
 114 .. code-block:: bash
 115
 116         root:/sys/bus/iio/devices/iio:device0> cat name
 117         adxl382
 118
 119 Show 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
 136 Set 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
 147 Set 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
 160 Set 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
 173 3. Device buffers
 174 =================
 175
 176 This driver supports IIO buffers.
 177
 178 All devices support retrieving the raw acceleration and temperature measurements
 179 using buffers.
 180
 181 Usage examples
 182 --------------
 183
 184 Select 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
 193 Set 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
 199 Enable buffer readings:
 200
 201 .. code-block:: bash
 202
 203         root:/sys/bus/iio/devices/iio:device0> echo 1 > buffer/enable
 204
 205 Obtain 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
 226 See ``Documentation/iio/iio_devbuf.rst`` for more information about how buffered
 227 data is structured.
 228
 229 4. IIO Interfacing Tools
 230 ========================
 231
 232 See ``Documentation/iio/iio_tools.rst`` for the description of the available IIO
 233 interfacing tools.