Add documentation for adxl380 driver which describes the driver device files and shows how the user may use the ABI for various scenarios (configuration, measurement, etc.). Signed-off-by: Ramona Gradinariu <ramona.gradinariu@xxxxxxxxxx> Signed-off-by: Antoniu Miclaus <antoniu.miclaus@xxxxxxxxxx> --- no changes in v2. Documentation/iio/adxl380.rst | 238 ++++++++++++++++++++++++++++++++++ Documentation/iio/index.rst | 1 + 2 files changed, 239 insertions(+) create mode 100644 Documentation/iio/adxl380.rst diff --git a/Documentation/iio/adxl380.rst b/Documentation/iio/adxl380.rst new file mode 100644 index 000000000000..a64e330a18ee --- /dev/null +++ b/Documentation/iio/adxl380.rst @@ -0,0 +1,238 @@ +.. 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. + +The ADXL380/ADXL382 offers industry leading noise, enabling precision +applications with minimal calibration. The low noise, and low power +ADXL380/ADXL382 enables accurate measurement in an environment with high +vibration, heart sounds and audio. + +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. diff --git a/Documentation/iio/index.rst b/Documentation/iio/index.rst index 4c13bfa2865c..1ce5b24d40aa 100644 --- a/Documentation/iio/index.rst +++ b/Documentation/iio/index.rst @@ -20,5 +20,6 @@ Industrial I/O Kernel Drivers ad7944 adis16475 adis16480 + adxl380 bno055 ep93xx_adc -- 2.45.2
