[PATCH v7 6/6] docs: iio: add documentation for adis16550 driver

Robert Budai
2025-02-11T19:59:16Z

Add documentation for adis16550 driver which describes the driver device
files and shows how the user may use the ABI for various scenarios
(configuration, measurement, etc.).

Co-developed-by: Antoniu Miclaus <antoniu.miclaus@analog.com>
Signed-off-by: Antoniu Miclaus <antoniu.miclaus@analog.com>
Signed-off-by: Ramona Gradinariu <ramona.gradinariu@analog.com>
Signed-off-by: Robert Budai <robert.budai@analog.com>
---
Documentation/iio/adis16550.rst | 376 ++++++++++++++++++++++++++++++++
Documentation/iio/index.rst | 1 +
2 files changed, 377 insertions(+)
create mode 100644 Documentation/iio/adis16550.rst

diff --git a/Documentation/iio/adis16550.rst b/Documentation/iio/adis16550.rst
new file mode 100644
index 000000000..f929c460a
--- /dev/null
+++ b/Documentation/iio/adis16550.rst
@@ -0,0 +1,376 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+================
+ADIS16550 driver
+================
+
+This driver supports Analog Device's IMUs on SPI bus.
+
+1. Supported devices
+====================
+
+* `ADIS16550 <https://www.analog.com/ADIS16550>`_
+
+The ADIS16550 is a complete inertial system that includes a triaxis gyroscope
+and a triaxis accelerometer. The factory calibration characterizes each sensor for
+sensitivity, bias, and alignment. As a result, each sensor has its own dynamic
+compensation formulas that provide accurate sensor measurements.
+
+1. Device attributes
+====================
+
+Accelerometer, gyroscope measurements are always provided. Furthermore, the
+driver offers the capability to retrieve the delta angle and the delta velocity
+measurements computed by the device.
+
+The delta angle measurements represent a calculation of angular displacement
+between each sample update, while the delta velocity measurements represent a
+calculation of linear velocity change between each sample update.
+
+Finally, temperature data are provided which show a coarse measurement of
+the temperature inside of the IMU device. This data is most useful for
+monitoring relative changes in the thermal environment.
+
+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 adis16550 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_low_pass_3db_frequency | Bandwidth for the accelerometer channels. |
++-------------------------------------------+----------------------------------------------------------+
+| in_accel_x_calibbias | Calibration offset for the X-axis accelerometer channel. |
++-------------------------------------------+----------------------------------------------------------+
+| in_accel_x_calibscale | Calibration scale for the X-axis accelerometer channel. |
++-------------------------------------------+----------------------------------------------------------+
+| in_accel_x_raw | Raw X-axis accelerometer channel value. |
++-------------------------------------------+----------------------------------------------------------+
+| in_accel_y_calibbias | Calibration offset for the Y-axis accelerometer channel. |
++-------------------------------------------+----------------------------------------------------------+
+| in_accel_y_calibscale | Calibration scale for the Y-axis accelerometer channel. |
++-------------------------------------------+----------------------------------------------------------+
+| 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_calibscale | Calibration scale for the Z-axis accelerometer channel. |
++-------------------------------------------+----------------------------------------------------------+
+| in_accel_z_raw | Raw Z-axis accelerometer channel value. |
++-------------------------------------------+----------------------------------------------------------+
+| in_deltavelocity_scale | Scale for delta velocity channels. |
++-------------------------------------------+----------------------------------------------------------+
+| in_deltavelocity_x_raw | Raw X-axis delta velocity channel value. |
++-------------------------------------------+----------------------------------------------------------+
+| in_deltavelocity_y_raw | Raw Y-axis delta velocity channel value. |
++-------------------------------------------+----------------------------------------------------------+
+| in_deltavelocity_z_raw | Raw Z-axis delta velocity channel value. |
++-------------------------------------------+----------------------------------------------------------+
+
++--------------------------------------------+------------------------------------------------------+
+| 3-Axis Gyroscope related device files | Description |
++--------------------------------------------+------------------------------------------------------+
+| in_anglvel_scale | Scale for the gyroscope channels. |
++--------------------------------------------+------------------------------------------------------+
+| in_anglvel_filter_low_pass_3db_frequency | Scale for the gyroscope channels. |
++--------------------------------------------+------------------------------------------------------+
+| in_anglvel_x_calibbias | Calibration offset for the X-axis gyroscope channel. |
++--------------------------------------------+------------------------------------------------------+
+| in_anglvel_x_calibscale | Calibration scale for the X-axis gyroscope channel. |
++--------------------------------------------+------------------------------------------------------+
+| in_anglvel_x_raw | Raw X-axis gyroscope channel value. |
++--------------------------------------------+------------------------------------------------------+
+| in_anglvel_y_calibbias | Calibration offset for the Y-axis gyroscope channel. |
++--------------------------------------------+------------------------------------------------------+
+| in_anglvel_y_calibscale | Calibration scale for the Y-axis gyroscope channel. |
++--------------------------------------------+------------------------------------------------------+
+| in_anglvel_y_raw | Raw Y-axis gyroscope channel value. |
++--------------------------------------------+------------------------------------------------------+
+| in_anglvel_z_calibbias | Calibration offset for the Z-axis gyroscope channel. |
++--------------------------------------------+------------------------------------------------------+
+| in_anglvel_z_calibscale | Calibration scale for the Z-axis gyroscope channel. |
++--------------------------------------------+------------------------------------------------------+
+| in_anglvel_z_raw | Raw Z-axis gyroscope channel value. |
++--------------------------------------------+------------------------------------------------------+
+| in_deltaangl_scale | Scale for delta angle channels. |
++--------------------------------------------+------------------------------------------------------+
+| in_deltaangl_x_raw | Raw X-axis delta angle channel value. |
++--------------------------------------------+------------------------------------------------------+
+| in_deltaangl_y_raw | Raw Y-axis delta angle channel value. |
++--------------------------------------------+------------------------------------------------------+
+| in_deltaangl_z_raw | Raw Z-axis delta angle channel value. |
++--------------------------------------------+------------------------------------------------------+
+
++----------------------------------+-------------------------------------------+
+| Temperature sensor related files | Description |
++----------------------------------+-------------------------------------------+
+| in_temp0_raw | Raw temperature channel value. |
++----------------------------------+-------------------------------------------+
+| in_temp0_offset | Offset for the temperature sensor channel.|
++----------------------------------+-------------------------------------------+
+| in_temp0_scale | Scale for the temperature sensor channel. |
++----------------------------------+-------------------------------------------+
+
++----------------------------+--------------------------------------------------------------------------------+
+| Miscellaneous device files | Description |
++----------------------------+--------------------------------------------------------------------------------+
+| name | Name of the IIO device. |
++----------------------------+--------------------------------------------------------------------------------+
+| sampling_frequency | Currently selected sample rate. |
++----------------------------+--------------------------------------------------------------------------------+
+
+The following table shows the adis16550 related device debug files, found in the
+specific device debug folder path ``/sys/kernel/debug/iio/iio:deviceX``.
+
++----------------------+-------------------------------------------------------------------------+
+| Debugfs device files | Description |
++----------------------+-------------------------------------------------------------------------+
+| serial_number | The serial number of the chip in hexadecimal format. |
++----------------------+-------------------------------------------------------------------------+
+| product_id | Chip specific product id (16550). |
++----------------------+-------------------------------------------------------------------------+
+| flash_count | The number of flash writes performed on the device. |
++----------------------+-------------------------------------------------------------------------+
+| firmware_revision | String containing the firmware revision in the following format ##.##. |
++----------------------+-------------------------------------------------------------------------+
+| firmware_date | String containing the firmware date in the following format mm-dd-yyyy. |
++----------------------+-------------------------------------------------------------------------+
+
+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 adis16550 driver offers data for 5 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 |
++--------------------------------------+---------------------------+
+| Angular velocity on X, Y and Z axis | Radians per second |
++--------------------------------------+---------------------------+
+| Delta velocity on X. Y, and Z axis | Meters per Second |
++--------------------------------------+---------------------------+
+| Delta angle on X, Y, and Z axis | Radians |
++--------------------------------------+---------------------------+
+| Temperature | Millidegrees Celsius |
++--------------------------------------+---------------------------+
+
+Usage examples
+--------------
+
+Show device name:
+
+.. code-block:: bash
+
+ root:/sys/bus/iio/devices/iio:device0> cat name
+ adis16550
+
+Show accelerometer channels value:
+
+.. code-block:: bash
+
+ root:/sys/bus/iio/devices/iio:device0> cat in_accel_x_raw
+ 6903851
+ root:/sys/bus/iio/devices/iio:device0> cat in_accel_y_raw
+ 5650550
+ root:/sys/bus/iio/devices/iio:device0> cat in_accel_z_raw
+ 104873530
+ root:/sys/bus/iio/devices/iio:device0> cat in_accel_scale
+ 0.000000095
+
+- X-axis acceleration = in_accel_x_raw * in_accel_scale = 0.655865845 m/s^2
+- Y-axis acceleration = in_accel_y_raw * in_accel_scale = 0.53680225 m/s^2
+- Z-axis acceleration = in_accel_z_raw * in_accel_scale = 9.96298535 m/s^2
+
+Show gyroscope channels value:
+
+.. code-block:: bash
+
+ root:/sys/bus/iio/devices/iio:device0> cat in_anglvel_x_raw
+ 193309
+ root:/sys/bus/iio/devices/iio:device0> cat in_anglvel_y_raw
+ -763676
+ root:/sys/bus/iio/devices/iio:device0> cat in_anglvel_z_raw
+ -358108
+ root:/sys/bus/iio/devices/iio:device0> cat in_anglvel_scale
+ 0.000000003
+
+- X-axis angular velocity = in_anglvel_x_raw * in_anglvel_scale = 0.000579927 rad/s
+- Y-axis angular velocity = in_anglvel_y_raw * in_anglvel_scale = −0.002291028 rad/s
+- Z-axis angular velocity = in_anglvel_z_raw * in_anglvel_scale = −0.001074324 rad/s
+
+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 5000 > in_accel_x_calibbias
+ root:/sys/bus/iio/devices/iio:device0> cat in_accel_x_calibbias
+ 5000
+
+Set calibration offset for gyroscope channels:
+
+.. code-block:: bash
+
+ root:/sys/bus/iio/devices/iio:device0> cat in_anglvel_y_calibbias
+ 0
+
+ root:/sys/bus/iio/devices/iio:device0> echo -5000 > in_anglvel_y_calibbias
+ root:/sys/bus/iio/devices/iio:device0> cat in_anglvel_y_calibbias
+ -5000
+
+Set sampling frequency:
+
+.. code-block:: bash
+
+ root:/sys/bus/iio/devices/iio:device0> cat sampling_frequency
+ 4000.000000
+
+ root:/sys/bus/iio/devices/iio:device0> echo 1000 > sampling_frequency
+ 1000.000000
+
+Set bandwidth for accelerometer channels:
+
+.. code-block:: bash
+
+ root:/sys/bus/iio/devices/iio:device0> cat in_accel_filter_low_pass_3db_frequency
+ 0
+
+ root:/sys/bus/iio/devices/iio:device0> echo 100 > in_accel_filter_low_pass_3db_frequency
+ root:/sys/bus/iio/devices/iio:device0> cat in_accel_filter_low_pass_3db_frequency
+ 100
+
+Show serial number:
+
+.. code-block:: bash
+
+ root:/sys/kernel/debug/iio/iio:device0> cat serial_number
+ 0x000000b6
+
+Show product id:
+
+.. code-block:: bash
+
+ root:/sys/kernel/debug/iio/iio:device0> cat product_id
+ 16550
+
+Show flash count:
+
+.. code-block:: bash
+
+ root:/sys/kernel/debug/iio/iio:device0> cat flash_count
+ 13
+
+Show firmware revision:
+
+.. code-block:: bash
+
+ root:/sys/kernel/debug/iio/iio:device0> cat firmware_revision
+ 1.5
+
+Show firmware date:
+
+.. code-block:: bash
+
+ root:/sys/kernel/debug/iio/iio:device0> cat firmware_date
+ 28-04-2021
+
+3. Device buffers
+=================
+
+This driver supports IIO buffers.
+
+The device supports retrieving the raw acceleration, gyroscope, delta velocity,
+delta angle and temperature measurements using buffers.
+
+However, when retrieving acceleration or gyroscope data using buffers, delta
+readings will not be available and vice versa. This is because the device only
+allows to read either acceleration and gyroscope data or delta velocity and
+delta angle data at a time and switching between these two burst data selection
+modes is time consuming.
+
+Usage examples
+--------------
+
+Set device trigger in current_trigger, if not already set:
+
+.. code-block:: bash
+
+ root:/sys/bus/iio/devices/iio:device0> cat trigger/current_trigger
+
+ root:/sys/bus/iio/devices/iio:device0> echo adis16550-dev0 > trigger/current_trigger
+ root:/sys/bus/iio/devices/iio:device0> cat trigger/current_trigger
+ adis16550-dev0
+
+Select channels for buffer read:
+
+.. code-block:: bash
+
+ root:/sys/bus/iio/devices/iio:device0> echo 1 > scan_elements/in_deltavelocity_x_en
+ root:/sys/bus/iio/devices/iio:device0> echo 1 > scan_elements/in_deltavelocity_y_en
+ root:/sys/bus/iio/devices/iio:device0> echo 1 > scan_elements/in_deltavelocity_z_en
+ root:/sys/bus/iio/devices/iio:device0> echo 1 > scan_elements/in_temp0_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
+ ...
+ 0000cdf0 00 00 0d 2f 00 00 08 43 00 00 09 09 00 00 a4 5f |.../...C......._|
+ 0000ce00 00 00 0d 2f 00 00 07 de 00 00 08 db 00 00 a4 4b |.../...........K|
+ 0000ce10 00 00 0d 2f 00 00 07 58 00 00 08 a3 00 00 a4 55 |.../...X.......U|
+ 0000ce20 00 00 0d 2f 00 00 06 d6 00 00 08 5c 00 00 a4 62 |.../.......\...b|
+ 0000ce30 00 00 0d 2f 00 00 06 45 00 00 08 37 00 00 a4 47 |.../...E...7...G|
+ 0000ce40 00 00 0d 2f 00 00 05 d4 00 00 08 30 00 00 a3 fa |.../.......0....|
+ 0000ce50 00 00 0d 2f 00 00 05 d0 00 00 08 12 00 00 a3 d3 |.../............|
+ 0000ce60 00 00 0d 2f 00 00 05 dd 00 00 08 2e 00 00 a3 e9 |.../............|
+ 0000ce70 00 00 0d 2f 00 00 05 cc 00 00 08 51 00 00 a3 d5 |.../.......Q....|
+ 0000ce80 00 00 0d 2f 00 00 05 ba 00 00 08 22 00 00 a3 9a |.../......."....|
+ 0000ce90 00 00 0d 2f 00 00 05 9c 00 00 07 d9 00 00 a3 40 |.../...........@|
+ 0000cea0 00 00 0d 2f 00 00 05 68 00 00 07 94 00 00 a2 e4 |.../...h........|
+ 0000ceb0 00 00 0d 2f 00 00 05 25 00 00 07 8d 00 00 a2 ce |.../...%........|
+ ...
+
+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 5710f5b9e..039ed2d75 100644
--- a/Documentation/iio/index.rst
+++ b/Documentation/iio/index.rst
@@ -26,6 +26,7 @@ Industrial I/O Kernel Drivers
ad7944
adis16475
adis16480
+ adis16550
adxl380
bno055
ep93xx_adc
--
2.34.1