This version is outdated by a newer approved version.
This version (28 Jan 2021 10:36) was approved by Michael Hennerich.The Previously approved version (02 Jan 2013 22:22) is available.
This version (28 Jan 2021 10:36) was approved by Michael Hennerich.The Previously approved version (02 Jan 2013 22:22) is available.This is an old revision of the document!
Table of Contents
iio-trig-sysfs driver
Description
This driver adds a trigger that can be invoked by writing the sysfs file: trigger_now. This approach can be valuable during automated testing or in situations, where other trigger methods are not applicable. For example no RTC or spare GPIOs. Last but not least it allows user space applications to produce triggers.
Adding Linux driver support
Configure kernel with “make menuconfig” (alternatively use “make xconfig” or “make qconfig”)
Linux Kernel Configuration Device Drivers ---> [*] Staging drivers ---> <*> Industrial I/O support ---> --- Industrial I/O support -*- Enable ring buffer support within IIO -*- Industrial I/O lock free software ring -*- Enable triggered sampling support [--snip--] *** Triggers - standalone *** < > Periodic RTC triggers < > GPIO trigger <*> SYSFS trigger < > Blackfin TIMER trigger
sysfs trigger creation and removal
When sysfs trigger support is enabled in the kernel configuration there will be a /sys/bus/iio/devices/iio_sysfs_trigger/ folder which can be used for sysfs trigger management. The folder contains two files “add_trigger” and “remove_trigger”. New sysfs triggers can be created by writing a ID to the “add_trigger” file. E.g. `echo 0 > add_trigger`. This will create a new sysfs trigger, which you can access at “/sys/bus/iio/devices/iio:triggerX”, where X is a the trigger number. Typically it will be 0 for the first trigger, 1 for the second, etc. The name of the trigger will be “sysfstrigID” where ID is the value writting to the “add_trigger” file.
To remove a sysfs trigger write the same ID used when registering it to the “remove_trigger” file. E.g `echo 0 > remove_trigger`.
Driver testing
This specifies any shell prompt running on the target
root:/> cd sys/bus/iio/devices/ root:/sys/bus/iio/devices> ls iio:device0 iio:device1 iio:trigger0 root:/sys/bus/iio/devices> cd iio:trigger0 root:/sys/devices/iio:trigger0> ls name subsystem trigger_now uevent root:/sys/devices/iio:trigger0> cat name sysfstrig0 root:/sys/devices/iio:trigger0> echo 1 > trigger_now root:/sys/devices/iio:trigger0> echo 1 > trigger_now
More Information
- IIO mailing list: linux [dash] iio [at] vger [dot] kernel [dot] org
software/linux/docs/iio/iio-trig-sysfs.1611826560.txt.gz · Last modified: 28 Jan 2021 10:36 by Michael Hennerich