pmeerw's blog

Sun, 26 Aug 2012

How to use the Linux Industrial IO (IIO) interface

IIO is a Linux subsystem intended to support reading sensors (or some kind of analog-to-digital convertors) including accelerometers, gyros, temperature/pressure/light sensors. It recently left staging (November 2011).

Reading sensor values via IIO can be done directly or in buffered mode. The later requires setup of a trigger.

Here is the script I use to test an Linux IIO driver I'm developping for the Si1143 ambient light/proximity sensor:

# load necessary modules
modprobe industrialio
modprobe iio-trig-sysfs
modprobe kfifo_buf
modprobe industrialio-triggered-buffer

# reload driver
rmmod si114x_new
insmod si114x-new.ko

# register new i2c device
echo si114x 0x5a > /sys/devices/platform/omap_i2c.2/i2c-2/new_device

# proximity reading (direct)
cat /sys/bus/iio/devices/iio:device0/in_proximity0_raw

# add new IIO sysfs trigger
echo 123 > /sys/bus/iio/devices/iio_sysfs_trigger/add_trigger
echo sysfstrig123 > /sys/bus/iio/devices/iio:device0/trigger/current_trigger

# enable some channels 
echo 1 > /sys/bus/iio/devices/iio:device0/scan_elements/in_proximity0_en
echo 1 > /sys/bus/iio/devices/iio:device0/scan_elements/in_intensity_en
echo 1 > /sys/bus/iio/devices/iio:device0/scan_elements/in_temp_en

# enable scan buffer
echo 100 > /sys/bus/iio/devices/iio:device0/buffer/length
echo 1 > /sys/bus/iio/devices/iio:device0/buffer/enable

# trigger to read data
echo 1 > /sys/bus/iio/devices/trigger0/trigger_now

# read the captured data (buffered)
cat /dev/iio\:device0 > /tmp/data.bin

posted at: 11:56 | path: /projects | permanent link

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