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[84.72.156.211]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-adf8b393ea8sm412692766b.159.2025.06.15.15.23.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 15 Jun 2025 15:23:14 -0700 (PDT) From: Lothar Rubusch To: jic23@kernel.org, dlechner@baylibre.com, nuno.sa@analog.com, andy@kernel.org, corbet@lwn.net, lucas.p.stankus@gmail.com, lars@metafoo.de, Michael.Hennerich@analog.com, bagasdotme@gmail.com Cc: l.rubusch@gmail.com, linux-iio@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v5 8/8] docs: iio: add ADXL313 accelerometer Date: Sun, 15 Jun 2025 22:22:58 +0000 Message-Id: <20250615222258.117771-9-l.rubusch@gmail.com> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250615222258.117771-1-l.rubusch@gmail.com> References: <20250615222258.117771-1-l.rubusch@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Add documentation for the ADXL313 accelerometer driver. Signed-off-by: Lothar Rubusch --- Documentation/iio/adxl313.rst | 289 ++++++++++++++++++++++++++++++++++ Documentation/iio/index.rst | 1 + 2 files changed, 290 insertions(+) create mode 100644 Documentation/iio/adxl313.rst diff --git a/Documentation/iio/adxl313.rst b/Documentation/iio/adxl313.rst new file mode 100644 index 000000000000..41b9cc37981c --- /dev/null +++ b/Documentation/iio/adxl313.rst @@ -0,0 +1,289 @@ +.. SPDX-License-Identifier: GPL-2.0 + +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D +ADXL313 driver +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D + +This driver supports Analog Device's ADXL313 on SPI/I2C bus. + +1. Supported devices +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D + +* `ADXL313 `_ + +The ADXL313is a low noise density, low power, 3-axis accelerometer with +selectable measurement ranges. The ADXL313 supports the =C2=B10.5 g, =C2= =B11 g, =C2=B12 g and +=C2=B14 g ranges. + +2. Device attributes +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D + +Accelerometer measurements are always provided. + +Each IIO device, has a device folder under ``/sys/bus/iio/devices/iio:devi= ceX``, +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 document= ed in +the IIO ABI documentation. + +The following tables show the adxl313 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 accele= rometer channels. | ++---------------------------------------------------+---------------------= -------------------------------------+ +| in_accel_x_calibbias | Calibration offset f= or the X-axis accelerometer channel. | ++---------------------------------------------------+---------------------= -------------------------------------+ +| in_accel_x_raw | Raw X-axis accelerom= eter channel value. | ++---------------------------------------------------+---------------------= -------------------------------------+ +| in_accel_y_calibbias | y-axis acceleration = offset correction | ++---------------------------------------------------+---------------------= -------------------------------------+ +| in_accel_y_raw | Raw Y-axis accelerom= eter channel value. | ++---------------------------------------------------+---------------------= -------------------------------------+ +| in_accel_z_calibbias | Calibration offset f= or the Z-axis accelerometer channel. | ++---------------------------------------------------+---------------------= -------------------------------------+ +| in_accel_z_raw | Raw Z-axis accelerom= eter channel value. | ++---------------------------------------------------+---------------------= -------------------------------------+ + ++---------------------------------------+---------------------------------= -------------+ +| Miscellaneous device files | Description = | ++---------------------------------------+---------------------------------= -------------+ +| name | Name of the IIO device. = | ++---------------------------------------+---------------------------------= -------------+ +| in_accel_sampling_frequency | Currently selected sample rate. = | ++---------------------------------------+---------------------------------= -------------+ +| in_accel_sampling_frequency_available | Available sampling frequency con= figurations. | ++---------------------------------------+---------------------------------= -------------+ + +The iio event related settings, found in ``/sys/bus/iio/devices/iio:device= X/events``. + ++---------------------------------------------------+---------------------= -------------------------------------+ +| in_accel_mag_adaptive_falling_period | AC coupled inactivit= y time. | ++---------------------------------------------------+---------------------= -------------------------------------+ +| in_accel_mag_adaptive_falling_value | AC coupled inactivit= y threshold. | ++---------------------------------------------------+---------------------= -------------------------------------+ +| in_accel_mag_adaptive_rising_value | AC coupled activity = threshold. | ++---------------------------------------------------+---------------------= -------------------------------------+ +| in_accel_mag_falling_period | Inactivity time. = | ++---------------------------------------------------+---------------------= -------------------------------------+ +| in_accel_mag_falling_value | Inactivity threshold= . | ++---------------------------------------------------+---------------------= -------------------------------------+ +| in_accel_mag_rising_value | Activity threshold. = | ++---------------------------------------------------+---------------------= -------------------------------------+ +| in_accel_x\&y\&z_mag_adaptive_falling_en | Enable or disable AC= coupled inactivity events. | ++---------------------------------------------------+---------------------= -------------------------------------+ +| in_accel_x\|y\|z_mag_adaptive_rising_en | Enable or disable AC= coupled activity events. | ++---------------------------------------------------+---------------------= -------------------------------------+ +| in_accel_x\&y\&z_mag_falling_en | Enable or disable in= activity events. | ++---------------------------------------------------+---------------------= -------------------------------------+ +| in_accel_x\|y\|z_mag_rising_en | Enable or disable ac= tivity events. | ++---------------------------------------------------+---------------------= -------------------------------------+ + +The default coupling is DC coupled events. In this case the threshold will +be in place as such, where for the AC coupled case an adaptive threshold +(described in the datasheet) will be applied by the sensor. In general act= ivity, +i.e. ``ACTIVITY`` or ``ACTIVITY_AC`` and inactivity i.e. ``INACTIVITY`` or +``INACTIVITY_AC``, will be linked with auto-sleep enabled when both are en= abled. +This means in particular ``ACTIVITY`` can also be linked to ``INACTIVITY_A= C`` +and vice versa, without problem. + +Note here, that ``ACTIVITY`` and ``ACTIVITY_AC`` are mutually exclusive. T= his +means, that the most recent configuration will be set. For instance, if +``ACTIVITY`` is enabled, and ``ACTIVITY_AC`` will be enabled, the sensor d= river +will have ``ACTIVITY`` disabled, but ``ACTIVITY_AC`` enabled. The same is = valid +for inactivity. In case of turning off an event, it has to match to what is +actually enabled, i.e. enabling ``ACTIVITY_AC`` and then disabling ``ACTIV= ITY`` +is simply ignored as it is already disabled. Or, as if it was any other not +enabled event, too. + +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 ch= annel, +apply the following formula: + +.. code-block:: + + processed value =3D (_raw + _offset) * _scale + +Where _offset and _scale are device attributes. If no _offset attribute is +present, simply assume its value is 0. + +The ADXL313 driver offers data for a single types of channels, the table b= elow +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 | ++-------------------------------------+---------------------------+ + +Usage examples +-------------- + +Show device name: + +.. code-block:: bash + + root:/sys/bus/iio/devices/iio:device0> cat name + adxl313 + +Show accelerometer channels value: + +.. code-block:: bash + + root:/sys/bus/iio/devices/iio:device0> cat in_accel_x_raw + 2 + root:/sys/bus/iio/devices/iio:device0> cat in_accel_y_raw + -57 + root:/sys/bus/iio/devices/iio:device0> cat in_accel_z_raw + 2 + root:/sys/bus/iio/devices/iio:device0> cat in_accel_scale + 0.009576806 + +The accelerometer values will be: + +- X-axis acceleration =3D in_accel_x_raw * in_accel_scale =3D 0.0191536 m/= s^2 +- Y-axis acceleration =3D in_accel_y_raw * in_accel_scale =3D -0.5458779 m= /s^2 +- Z-axis acceleration =3D in_accel_z_raw * in_accel_scale =3D 0.0191536 m/= s^2 + +Set calibration offset for accelerometer channels. Note, that the calibrat= ion +will be rounded according to the graduation of LSB units: + +.. 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_calibb= ias + root:/sys/bus/iio/devices/iio:device0> cat in_accel_x_calibbias + 48 + +Set sampling frequency: + +.. code-block:: bash + + root:/sys/bus/iio/devices/iio:device0> cat in_accel_sampling_frequ= ency + 100.000000 + root:/sys/bus/iio/devices/iio:device0> cat in_accel_sampling_frequ= ency_available + 6.250000 12.500000 25.000000 50.000000 100.000000 200.000000 400.0= 00000 800.000000 1600.000000 3200.000000 + + root:/sys/bus/iio/devices/iio:device0> echo 400 > in_accel_samplin= g_frequency + root:/sys/bus/iio/devices/iio:device0> cat in_accel_sampling_frequ= ency + 400.000000 + +3. Device buffers and triggers +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D + +This driver supports IIO buffers. + +All devices support retrieving the raw acceleration measurements using buf= fers. + +Usage examples +-------------- + +Select channels for buffer read: + +.. code-block:: bash + + root:/sys/bus/iio/devices/iio:device0> echo 1 > scan_elements/in_a= ccel_x_en + root:/sys/bus/iio/devices/iio:device0> echo 1 > scan_elements/in_a= ccel_y_en + root:/sys/bus/iio/devices/iio:device0> echo 1 > scan_elements/in_a= ccel_z_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 + ... + 000000d0 01 fc 31 00 c7 ff 03 fc 31 00 c7 ff 04 fc 33 00 |..1..= ...1.....3.| + 000000e0 c8 ff 03 fc 32 00 c5 ff ff fc 32 00 c7 ff 0a fc |....2= .....2.....| + 000000f0 30 00 c8 ff 06 fc 33 00 c7 ff 01 fc 2f 00 c8 ff |0....= .3...../...| + 00000100 02 fc 32 00 c6 ff 04 fc 33 00 c8 ff 05 fc 33 00 |..2..= ...3.....3.| + 00000110 ca ff 02 fc 31 00 c7 ff 02 fc 30 00 c9 ff 09 fc |....1= .....0.....| + 00000120 35 00 c9 ff 08 fc 35 00 c8 ff 02 fc 31 00 c5 ff |5....= .5.....1...| + 00000130 03 fc 32 00 c7 ff 04 fc 32 00 c7 ff 02 fc 31 00 |..2..= ...2.....1.| + 00000140 c7 ff 08 fc 30 00 c7 ff 02 fc 32 00 c5 ff ff fc |....0= .....2.....| + 00000150 31 00 c5 ff 04 fc 31 00 c8 ff 03 fc 32 00 c8 ff |1....= .1.....2...| + 00000160 01 fc 31 00 c7 ff 05 fc 31 00 c3 ff 04 fc 31 00 |..1..= ...1.....1.| + 00000170 c5 ff 04 fc 30 00 c7 ff 03 fc 31 00 c9 ff 03 fc |....0= .....1.....| + ... + +Enabling activity detection: + +.. code-block:: bash + root:/sys/bus/iio/devices/iio:device0> echo 1.28125 > ./events/in_= accel_mag_rising_value + root:/sys/bus/iio/devices/iio:device0> echo 1 > ./events/in_accel_= x\|y\|z_mag_rising_en + + root:/sys/bus/iio/devices/iio:device0> iio_event_monitor adxl313 + Found IIO device with name adxl313 with device number 0 + + Event: time: 1748795762298351281, type: accel(x|y|z), channel: 0, = evtype: mag, direction: rising + Event: time: 1748795762302653704, type: accel(x|y|z), channel: 0, = evtype: mag, direction: rising + Event: time: 1748795762304340726, type: accel(x|y|z), channel: 0, = evtype: mag, direction: rising + ... + +Disabling activity detection: + +.. code-block:: bash + root:/sys/bus/iio/devices/iio:device0> echo 0 > ./events/in_accel_= x\|y\|z_mag_rising_en + root:/sys/bus/iio/devices/iio:device0> iio_event_monitor adxl313 + + +Enabling inactivity detection: + +.. code-block:: bash + root:/sys/bus/iio/devices/iio:device0> echo 1.234375 > ./events/in= _accel_mag_falling_value + root:/sys/bus/iio/devices/iio:device0> echo 5 > ./events/in_accel_= mag_falling_period + root:/sys/bus/iio/devices/iio:device0> echo 1 > ./events/in_accel_= x\&y\&z_mag_falling_en + + root:/sys/bus/iio/devices/iio:device0> iio_event_monitor adxl313 + Found IIO device with name adxl313 with device number 0 + Event: time: 1748796324115962975, type: accel(x&y&z), channel: 0, = evtype: mag, direction: falling + Event: time: 1748796329329981772, type: accel(x&y&z), channel: 0, = evtype: mag, direction: falling + Event: time: 1748796334543399706, type: accel(x&y&z), channel: 0, = evtype: mag, direction: falling + ... + + +Now, enabling activity, e.g. the AC coupled counter-part ``ACTIVITY_AC`` + +.. code-block:: bash + root:/sys/bus/iio/devices/iio:device0> echo 1.28125 > ./events/in_= accel_mag_rising_value + root:/sys/bus/iio/devices/iio:device0> echo 1 > ./events/in_accel_= x\|y\|z_mag_rising_en + + root:/sys/bus/iio/devices/iio:device0> iio_event_monitor adxl313 + Found IIO device with name adxl313 with device number 0 + + Event: time: 1748796880354686777, type: accel(x|y|z), channel: 0, = evtype: mag_adaptive, direction: rising + <5s of inactivity, then> + Event: time: 1748796885543252017, type: accel(x&y&z), channel: 0, = evtype: mag, direction: falling + + Event: time: 1748796887756634678, type: accel(x|y|z), channel: 0, = evtype: mag_adaptive, direction: rising + + Event: time: 1748796892964368352, type: accel(x&y&z), channel: 0, = evtype: mag, direction: falling + + +Note, when AC coupling is in place, the event type will be of ``mag_adapti= ve``. +AC- or DC-coupled (the default) events are used similarly. + +4. IIO Interfacing Tools +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D + +See Documentation/iio/iio_tools.rst for the description of the available I= IO +interfacing tools. diff --git a/Documentation/iio/index.rst b/Documentation/iio/index.rst index 2d6afc5a8ed5..c106402a91f7 100644 --- a/Documentation/iio/index.rst +++ b/Documentation/iio/index.rst @@ -31,6 +31,7 @@ Industrial I/O Kernel Drivers adis16475 adis16480 adis16550 + adxl313 adxl380 bno055 ep93xx_adc --=20 2.39.5