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resources:tools-software:linux-drivers:iio-dac:ad5593r [22 Feb 2016 17:52] – [Device tree example] Michael Hennerichresources:tools-software:linux-drivers:iio-dac:ad5593r [23 Feb 2016 13:25] – [Driver testing] Michael Hennerich
Line 164: Line 164:
                                 attr 2: scale value: 452.147700000                                 attr 2: scale value: 452.147700000
  
 +</code>
 +
 +=== GPIO Testing  ===
 +
 +The GPIO sysfs interface allows users to manipulate any GPIO from userspace.
 +
 +Userspace utilizes a sysfs control interface to dynamically request and release individual GPIOs. Once a GPIO has been requested, writing to the newly created path allows you to control the direction and the data while reading from it returns the GPIO data (which usually corresponds to a 0 or 1 which represents the signal level).
 +
 +For more information see also here:
 +
 +<code>
 +root@linaro-ubuntu-desktop:~# cd /sys/class/gpio/
 +root@linaro-ubuntu-desktop:/sys/class/gpio# ls
 +export  gpiochip890  gpiochip898  gpiochip906  unexport
 +
 +root@linaro-ubuntu-desktop:/sys/class/gpio# cd gpiochip890
 +
 +root@linaro-ubuntu-desktop:/sys/class/gpio/gpiochip890# ls -al
 +total 0
 +drwxr-xr-x 3 root root    0 Jan  1  1970 .
 +drwxr-xr-x 3 root root    0 Jan  1  1970 ..
 +-r--r--r-- 1 root root 4096 Feb 23 08:06 base
 +lrwxrwxrwx 1 root root    0 Feb 23 08:06 device -> ../../../0-0010
 +-r--r--r-- 1 root root 4096 Feb 23 08:06 label
 +-r--r--r-- 1 root root 4096 Feb 23 08:06 ngpio
 +drwxr-xr-x 2 root root    0 Feb 23 08:06 power
 +lrwxrwxrwx 1 root root    0 Jan  1  1970 subsystem -> ../../../../../../../../class/gpio
 +-rw-r--r-- 1 root root 4096 Jan  1  1970 uevent
 +
 +root@linaro-ubuntu-desktop:/sys/class/gpio/gpiochip890# grep "" *
 +base:890
 +label:0-0010
 +ngpio:8
 +
 +
 +root@linaro-ubuntu-desktop:/sys/class/gpio/gpiochip890# cd ..
 +root@linaro-ubuntu-desktop:/sys/class/gpio# echo 897 > export 
 +root@linaro-ubuntu-desktop:/sys/class/gpio# cd gpio897/
 +root@linaro-ubuntu-desktop:/sys/class/gpio/gpio897# ls -al
 +total 0
 +drwxr-xr-x 3 root root    0 Feb 23 08:06 .
 +drwxr-xr-x 4 root root    0 Feb 23 08:06 ..
 +-rw-r--r-- 1 root root 4096 Feb 23 08:06 active_low
 +lrwxrwxrwx 1 root root    0 Feb 23 08:06 device -> ../../../0-0010
 +-rw-r--r-- 1 root root 4096 Feb 23 08:06 direction
 +drwxr-xr-x 2 root root    0 Feb 23 08:06 power
 +lrwxrwxrwx 1 root root    0 Feb 23 08:06 subsystem -> ../../../../../../../../class/gpio
 +-rw-r--r-- 1 root root 4096 Feb 23 08:06 uevent
 +-rw-r--r-- 1 root root 4096 Feb 23 08:06 value
 +
 +root@linaro-ubuntu-desktop:/sys/class/gpio/gpio897# cat direction 
 +in
 +
 +root@linaro-ubuntu-desktop:/sys/class/gpio/gpio897# cat value 
 +0
 +
 +root@linaro-ubuntu-desktop:/sys/class/gpio/gpio897# echo low > direction 
 +
 +root@linaro-ubuntu-desktop:/sys/class/gpio/gpio897# cat direction 
 +out
 +
 +root@linaro-ubuntu-desktop:/sys/class/gpio/gpio897# cat value 
 +0
 +
 +root@linaro-ubuntu-desktop:/sys/class/gpio/gpio897# echo high > direction                                                                                                                                    
 +
 +root@linaro-ubuntu-desktop:/sys/class/gpio/gpio897# cat value 
 +1
 </code> </code>
resources/tools-software/linux-drivers/iio-dac/ad5593r.txt · Last modified: 19 Jan 2018 10:12 by Alexandru Ardelean