1 .. SPDX-License-Identifier: GPL-2.0
7 This driver supports Analog Device's IMUs on SPI bus.
12 * `ADIS16465 <https://www.analog.com/ADIS16465>`_
13 * `ADIS16467 <https://www.analog.com/ADIS16467>`_
14 * `ADIS16470 <https://www.analog.com/ADIS16470>`_
15 * `ADIS16475 <https://www.analog.com/ADIS16475>`_
16 * `ADIS16477 <https://www.analog.com/ADIS16477>`_
17 * `ADIS16500 <https://www.analog.com/ADIS16500>`_
18 * `ADIS16505 <https://www.analog.com/ADIS16505>`_
19 * `ADIS16507 <https://www.analog.com/ADIS16507>`_
21 Each supported device is a precision, miniature microelectromechanical system
22 (MEMS) inertial measurement unit (IMU) that includes a triaxial gyroscope and a
23 triaxial accelerometer. Each inertial sensor in the IMU device combines with
24 signal conditioning that optimizes dynamic performance. The factory calibration
25 characterizes each sensor for sensitivity, bias, alignment, linear acceleration
26 (gyroscope bias), and point of percussion (accelerometer location). As a result,
27 each sensor has dynamic compensation formulas that provide accurate sensor
28 measurements over a broad set of conditions.
33 Accelerometer, gyroscope measurements are always provided. Furthermore, the
34 driver offers the capability to retrieve the delta angle and the delta velocity
35 measurements computed by the device.
37 The delta angle measurements represent a calculation of angular displacement
38 between each sample update, while the delta velocity measurements represent a
39 calculation of linear velocity change between each sample update.
41 Finally, temperature data are provided which show a coarse measurement of
42 the temperature inside of the IMU device. This data is most useful for
43 monitoring relative changes in the thermal environment.
45 The signal chain of each inertial sensor (accelerometers and gyroscopes)
46 includes the application of unique correction formulas, which are derived from
47 extensive characterization of bias, sensitivity, alignment, response to linear
48 acceleration (gyroscopes), and point of percussion (accelerometer location)
49 over a temperature range of −40°C to +85°C, for each ADIS device. These
50 correction formulas are not accessible, but users do have the opportunity to
51 adjust the bias for each sensor individually through the calibbias attribute.
53 Each IIO device, has a device folder under ``/sys/bus/iio/devices/iio:deviceX``,
54 where X is the IIO index of the device. Under these folders reside a set of
55 device files, depending on the characteristics and features of the hardware
56 device in questions. These files are consistently generalized and documented in
57 the IIO ABI documentation.
59 The following tables show the adis16475 related device files, found in the
60 specific device folder path ``/sys/bus/iio/devices/iio:deviceX``.
62 +-------------------------------------------+----------------------------------------------------------+
63 | 3-Axis Accelerometer related device files | Description |
64 +-------------------------------------------+----------------------------------------------------------+
65 | in_accel_scale | Scale for the accelerometer channels. |
66 +-------------------------------------------+----------------------------------------------------------+
67 | in_accel_x_calibbias | Calibration offset for the X-axis accelerometer channel. |
68 +-------------------------------------------+----------------------------------------------------------+
69 | in_accel_calibbias_x | x-axis acceleration offset correction |
70 +-------------------------------------------+----------------------------------------------------------+
71 | in_accel_x_raw | Raw X-axis accelerometer channel value. |
72 +-------------------------------------------+----------------------------------------------------------+
73 | in_accel_calibbias_y | y-axis acceleration offset correction |
74 +-------------------------------------------+----------------------------------------------------------+
75 | in_accel_y_raw | Raw Y-axis accelerometer channel value. |
76 +-------------------------------------------+----------------------------------------------------------+
77 | in_accel_z_calibbias | Calibration offset for the Z-axis accelerometer channel. |
78 +-------------------------------------------+----------------------------------------------------------+
79 | in_accel_z_raw | Raw Z-axis accelerometer channel value. |
80 +-------------------------------------------+----------------------------------------------------------+
81 | in_deltavelocity_scale | Scale for delta velocity channels. |
82 +-------------------------------------------+----------------------------------------------------------+
83 | in_deltavelocity_x_raw | Raw X-axis delta velocity channel value. |
84 +-------------------------------------------+----------------------------------------------------------+
85 | in_deltavelocity_y_raw | Raw Y-axis delta velocity channel value. |
86 +-------------------------------------------+----------------------------------------------------------+
87 | in_deltavelocity_z_raw | Raw Z-axis delta velocity channel value. |
88 +-------------------------------------------+----------------------------------------------------------+
90 +---------------------------------------+------------------------------------------------------+
91 | 3-Axis Gyroscope related device files | Description |
92 +---------------------------------------+------------------------------------------------------+
93 | in_anglvel_scale | Scale for the gyroscope channels. |
94 +---------------------------------------+------------------------------------------------------+
95 | in_anglvel_x_calibbias | Calibration offset for the X-axis gyroscope channel. |
96 +---------------------------------------+------------------------------------------------------+
97 | in_anglvel_calibbias_x | x-axis gyroscope offset correction |
98 +---------------------------------------+------------------------------------------------------+
99 | in_anglvel_x_raw | Raw X-axis gyroscope channel value. |
100 +---------------------------------------+------------------------------------------------------+
101 | in_anglvel_calibbias_y | y-axis gyroscope offset correction |
102 +---------------------------------------+------------------------------------------------------+
103 | in_anglvel_y_raw | Raw Y-axis gyroscope channel value. |
104 +---------------------------------------+------------------------------------------------------+
105 | in_anglvel_z_calibbias | Calibration offset for the Z-axis gyroscope channel. |
106 +---------------------------------------+------------------------------------------------------+
107 | in_anglvel_z_raw | Raw Z-axis gyroscope channel value. |
108 +---------------------------------------+------------------------------------------------------+
109 | in_deltaangl_scale | Scale for delta angle channels. |
110 +---------------------------------------+------------------------------------------------------+
111 | in_deltaangl_x_raw | Raw X-axis delta angle channel value. |
112 +---------------------------------------+------------------------------------------------------+
113 | in_deltaangl_y_raw | Raw Y-axis delta angle channel value. |
114 +---------------------------------------+------------------------------------------------------+
115 | in_deltaangl_z_raw | Raw Z-axis delta angle channel value. |
116 +---------------------------------------+------------------------------------------------------+
118 +----------------------------------+-------------------------------------------+
119 | Temperature sensor related files | Description |
120 +----------------------------------+-------------------------------------------+
121 | in_temp0_raw | Raw temperature channel value. |
122 +----------------------------------+-------------------------------------------+
123 | in_temp0_scale | Scale for the temperature sensor channel. |
124 +----------------------------------+-------------------------------------------+
126 +-------------------------------+---------------------------------------------------------+
127 | Miscellaneous device files | Description |
128 +-------------------------------+---------------------------------------------------------+
129 | name | Name of the IIO device. |
130 +-------------------------------+---------------------------------------------------------+
131 | sampling_frequency | Currently selected sample rate. |
132 +-------------------------------+---------------------------------------------------------+
133 | filter_low_pass_3db_frequency | Bandwidth for the accelerometer and gyroscope channels. |
134 +-------------------------------+---------------------------------------------------------+
136 The following table shows the adis16475 related device debug files, found in the
137 specific device debug folder path ``/sys/kernel/debug/iio/iio:deviceX``.
139 +----------------------+-------------------------------------------------------------------------+
140 | Debugfs device files | Description |
141 +----------------------+-------------------------------------------------------------------------+
142 | serial_number | The serial number of the chip in hexadecimal format. |
143 +----------------------+-------------------------------------------------------------------------+
144 | product_id | Chip specific product id (e.g. 16475, 16500, 16505, etc.). |
145 +----------------------+-------------------------------------------------------------------------+
146 | flash_count | The number of flash writes performed on the device. |
147 +----------------------+-------------------------------------------------------------------------+
148 | firmware_revision | String containing the firmware revision in the following format ##.##. |
149 +----------------------+-------------------------------------------------------------------------+
150 | firmware_date | String containing the firmware date in the following format mm-dd-yyyy. |
151 +----------------------+-------------------------------------------------------------------------+
153 Channels processed values
154 -------------------------
156 A channel value can be read from its _raw attribute. The value returned is the
157 raw value as reported by the devices. To get the processed value of the channel,
158 apply the following formula:
162 processed value = (_raw + _offset) * _scale
164 Where _offset and _scale are device attributes. If no _offset attribute is
165 present, simply assume its value is 0.
167 The adis16475 driver offers data for 5 types of channels, the table below shows
168 the measurement units for the processed value, which are defined by the IIO
171 +-------------------------------------+---------------------------+
172 | Channel type | Measurement unit |
173 +-------------------------------------+---------------------------+
174 | Acceleration on X, Y, and Z axis | Meters per Second squared |
175 +-------------------------------------+---------------------------+
176 | Angular velocity on X, Y and Z axis | Radians per second |
177 +-------------------------------------+---------------------------+
178 | Delta velocity on X. Y, and Z axis | Meters per Second |
179 +-------------------------------------+---------------------------+
180 | Delta angle on X, Y, and Z axis | Radians |
181 +-------------------------------------+---------------------------+
182 | Temperature | Millidegrees Celsius |
183 +-------------------------------------+---------------------------+
192 root:/sys/bus/iio/devices/iio:device0> cat name
195 Show accelerometer channels value:
199 root:/sys/bus/iio/devices/iio:device0> cat in_accel_x_raw
201 root:/sys/bus/iio/devices/iio:device0> cat in_accel_y_raw
203 root:/sys/bus/iio/devices/iio:device0> cat in_accel_z_raw
205 root:/sys/bus/iio/devices/iio:device0> cat in_accel_scale
208 - X-axis acceleration = in_accel_x_raw * in_accel_scale = −0.010209188 m/s^2
209 - Y-axis acceleration = in_accel_y_raw * in_accel_scale = −1.115262214 m/s^2
210 - Z-axis acceleration = in_accel_z_raw * in_accel_scale = 9.666833453 m/s^2
212 Show gyroscope channels value:
216 root:/sys/bus/iio/devices/iio:device0> cat in_anglvel_x_raw
218 root:/sys/bus/iio/devices/iio:device0> cat in_anglvel_y_raw
220 root:/sys/bus/iio/devices/iio:device0> cat in_anglvel_z_raw
222 root:/sys/bus/iio/devices/iio:device0> cat in_anglvel_scale
225 - X-axis angular velocity = in_anglvel_x_raw * in_anglvel_scale = −0.019947756 rad/s
226 - Y-axis angular velocity = in_anglvel_y_raw * in_anglvel_scale = 0.00802188 rad/s
227 - Z-axis angular velocity = in_anglvel_z_raw * in_anglvel_scale = −0.003617898 rad/s
229 Set calibration offset for accelerometer channels:
233 root:/sys/bus/iio/devices/iio:device0> cat in_accel_x_calibbias
236 root:/sys/bus/iio/devices/iio:device0> echo 5000 > in_accel_x_calibbias
237 root:/sys/bus/iio/devices/iio:device0> cat in_accel_x_calibbias
240 Set calibration offset for gyroscope channels:
244 root:/sys/bus/iio/devices/iio:device0> cat in_anglvel_y_calibbias
247 root:/sys/bus/iio/devices/iio:device0> echo -5000 > in_anglvel_y_calibbias
248 root:/sys/bus/iio/devices/iio:device0> cat in_anglvel_y_calibbias
251 Set sampling frequency:
255 root:/sys/bus/iio/devices/iio:device0> cat sampling_frequency
258 root:/sys/bus/iio/devices/iio:device0> echo 1000 > sampling_frequency
261 Set bandwidth for accelerometer and gyroscope:
265 root:/sys/bus/iio/devices/iio:device0> cat filter_low_pass_3db_frequency
268 root:/sys/bus/iio/devices/iio:device0> echo 360 > filter_low_pass_3db_frequency
269 root:/sys/bus/iio/devices/iio:device0> cat filter_low_pass_3db_frequency
276 root:/sys/kernel/debug/iio/iio:device0> cat serial_number
283 root:/sys/kernel/debug/iio/iio:device0> cat product_id
290 root:/sys/kernel/debug/iio/iio:device0> cat flash_count
293 Show firmware revision:
297 root:/sys/kernel/debug/iio/iio:device0> cat firmware_revision
304 root:/sys/kernel/debug/iio/iio:device0> cat firmware_date
310 This driver supports IIO buffers.
312 All devices support retrieving the raw acceleration, gyroscope and temperature
313 measurements using buffers.
315 The following device families also support retrieving the delta velocity, delta
316 angle and temperature measurements using buffers:
323 However, when retrieving acceleration or gyroscope data using buffers, delta
324 readings will not be available and vice versa.
329 Set device trigger in current_trigger, if not already set:
333 root:/sys/bus/iio/devices/iio:device0> cat trigger/current_trigger
335 root:/sys/bus/iio/devices/iio:device0> echo adis16505-2-dev0 > trigger/current_trigger
336 root:/sys/bus/iio/devices/iio:device0> cat trigger/current_trigger
339 Select channels for buffer read:
343 root:/sys/bus/iio/devices/iio:device0> echo 1 > scan_elements/in_deltavelocity_x_en
344 root:/sys/bus/iio/devices/iio:device0> echo 1 > scan_elements/in_deltavelocity_y_en
345 root:/sys/bus/iio/devices/iio:device0> echo 1 > scan_elements/in_deltavelocity_z_en
346 root:/sys/bus/iio/devices/iio:device0> echo 1 > scan_elements/in_temp0_en
348 Set the number of samples to be stored in the buffer:
352 root:/sys/bus/iio/devices/iio:device0> echo 10 > buffer/length
354 Enable buffer readings:
358 root:/sys/bus/iio/devices/iio:device0> echo 1 > buffer/enable
360 Obtain buffered data:
364 root:/sys/bus/iio/devices/iio:device0> hexdump -C /dev/iio\:device0
366 00001680 01 1f 00 00 ff ff fe ef 00 00 47 bf 00 03 35 55 |..........G...5U|
367 00001690 01 1f 00 00 ff ff ff d9 00 00 46 f1 00 03 35 35 |..........F...55|
368 000016a0 01 1f 00 00 ff ff fe fc 00 00 46 cb 00 03 35 7b |..........F...5{|
369 000016b0 01 1f 00 00 ff ff fe 41 00 00 47 0d 00 03 35 8b |.......A..G...5.|
370 000016c0 01 1f 00 00 ff ff fe 37 00 00 46 b4 00 03 35 90 |.......7..F...5.|
371 000016d0 01 1d 00 00 ff ff fe 5a 00 00 45 d7 00 03 36 08 |.......Z..E...6.|
372 000016e0 01 1b 00 00 ff ff fe fb 00 00 45 e7 00 03 36 60 |..........E...6`|
373 000016f0 01 1a 00 00 ff ff ff 17 00 00 46 bc 00 03 36 de |..........F...6.|
374 00001700 01 1a 00 00 ff ff fe 59 00 00 46 d7 00 03 37 b8 |.......Y..F...7.|
375 00001710 01 1a 00 00 ff ff fe ae 00 00 46 95 00 03 37 ba |..........F...7.|
376 00001720 01 1a 00 00 ff ff fe c5 00 00 46 63 00 03 37 9f |..........Fc..7.|
377 00001730 01 1a 00 00 ff ff fe 55 00 00 46 89 00 03 37 c1 |.......U..F...7.|
378 00001740 01 1a 00 00 ff ff fe 31 00 00 46 aa 00 03 37 f7 |.......1..F...7.|
381 See ``Documentation/iio/iio_devbuf.rst`` for more information about how buffered
384 4. IIO Interfacing Tools
385 ========================
390 Linux Kernel provides some userspace tools that can be used to retrieve data
393 * lsiio: example application that provides a list of IIO devices and triggers
394 * iio_event_monitor: example application that reads events from an IIO device
396 * iio_generic_buffer: example application that reads data from buffer
397 * iio_utils: set of APIs, typically used to access sysfs files.
402 LibIIO is a C/C++ library that provides generic access to IIO devices. The
403 library abstracts the low-level details of the hardware, and provides a simple
404 yet complete programming interface that can be used for advanced projects.
406 For more information about LibIIO, please see:
407 https://github.com/analogdevicesinc/libiio