61 lines
2.4 KiB
Plaintext
61 lines
2.4 KiB
Plaintext
Userspace access to IIO
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Example, ST Microelectronics LIS3L02DQ accelerometer.
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Typical sysfs entries (pruned for clarity)
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/sys/class/iio
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device0 - iio_dev related elements
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name - driver specific identifier (here lis3l02dq)
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accel_x - polled (or from ring) raw readout of acceleration
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accel_x_gain - hardware gain (calibration)
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accel_x_offset - hardware offset (calibration)
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available_sampling_frequency
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available_sampling_frequency - what options are there
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sampling_frequency - control of internal sampling frequency
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scan_elements - controls which channels will be stored in the ring buffer
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scan_en_accel_x
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scan_en_accel_y
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scan_en_timestamp
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device - link to underlying hardware device
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uevent - udev related element
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thresh - unified threshold used for detection on all axis
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event_line0_sources - which events are enabled
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accel_x_high - enable x axis high threshold event
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accel_x_low - enable x axis low threshold event
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event_line0 - event interface
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dev - major:minor for the chrdev (note major allocation dynamic)
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trigger - consumer attachement
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current_trigger - name based association with a trigger
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ring_buffer0 - ring buffer interface
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bps - byptes per sample (read only), dependant on scan element selection
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length - (rw) specificy length fo software ring buffer (typically ro in hw case)
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ring_enable - turn the ring on. If its the first to be enabled attached to this
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trigger will also enable the trigger.
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ring_access0
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dev - major:minor for ring buffer access chrdev
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ring_event_line0
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dev - major:minor for ring buffer event chrdev
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trigger0 - data ready trigger elements
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name - unqiue name of trigger
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Udev will create the following entries under /dev by default:
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ring_access0 - ring access chrdev
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ring_event0 - ring event chrdev
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event_line0 - general event chrdev.
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For the example code we assume the following rules have been used to ensure
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unique and consistent naming of these for the lis3l02dq in question:
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KERNEL="ring_event_line*", ID="spi1.0", DRIVER="lis3l02dq", NAME="iio/lis3l02dq_ring_event"
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KERNEL="event_line*", ID="spi1.0", DRIVER="lis3l02dq", NAME="iio/lis3l02dq_event"
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KERNEL="ring_access*", ID="spi1.0", DRIVER="lis3l02dq", NAME="iio/lis3l02dq_ring_access"
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The files, lis3l02dqbuffersimple.c and iio_util.h in this directory provide an example
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of how to use the ring buffer and event interfaces.
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