Hi, Can anyone tell me the procedure(s) to allow me to access the Braswell pins [from the file system] without having to go to root? Right now, I have to do Sudo su (and give my password) and then I can do the following and it works (turning an LED on and off): # echo 346 > /sys/class/gpio/export # echo out > /sys/class/gpio/gpio346/direction # echo 1 > /sys/class/gpio/gpio346/value # echo 0 > /sys/class/gpio/gpio346/value # echo 346 > /sys/class/gpio/unexport But, how do I do this without needing root permission? Here's the kernel and OS I'm running. Linux NODE-UDOOX86 4.4.0-53-generic #74-Ubuntu SMP Fri Dec 2 15:59:10 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux Frank
You have to create a user group, give that group the proper access to the gpio folders through the udev rules and add your user to the group. For an example see this discussion: GPIO through /sys/class
OK. That was for a Neo that has a different Arduino onboard. So, how do you do it for an x86? Is this process documented somewhere?
It is not yet documented for the Udoo X86 so you are free to do it for us. It has nothing to do with the Arduino part. It is just Linux only. It also depends on the Linux version and distro that people are using. You probably just can use the same commands as in the Neo discussion. The location of the udev file is probably different but that is the only difference. Please keep us updated!
Well, I'm not real sure about these steps because they've kind of been borrowed from several places, but this is what I did (and I have been able to recreate it). sudo groupadd gpio sudo usermod -G gpio <user> I created a file called gpio.rules in the /etc/udev/rules.d directory. in the gpio.rules file (and this is where I'm not sure exactly what needs to be in there): SUBSYSTEM=="gpio*", PROGRAM="/bin/sh -c 'chown -R root:gpio /sys/class/gpio && chmod -R 770 /sys/class/gpio; chown -R root:gpio /sys/devices/virtual/gpio && chmod -R 770 /sys/devices/virtual/gpio'" SUBSYSTEM=="gpio", ACTION=="add", PROGRAM="/bin/sh -c 'chown -R root:gpio /sys%p'" SUBSYSTEM=="gpio", ACTION=="add", PROGRAM="/bin/sh -c 'chmod -R g+rw /sys%p'" SUBSYSTEM=="gpio", ACTION=="add", PROGRAM="/bin/sh -c 'chown -R root:gpio /sys/class/gpio/export'" SUBSYSTEM=="gpio", ACTION=="add", PROGRAM="/bin/sh -c 'chmod -R g+w /sys/class/gpio/export'" and, reboot. If I delete the group gpio - I get permission denied on trying to do one of my file system GPIO calls. If I remove the group gpio from the user - I get permission denied on trying to do one of my file system GPIO calls. If I remove the gpio.rules file (and reboot) - I get permission denied on trying to do one of my file system GPIO calls. But, if I have all of these in place - the file system GPIO calls seem to work. I'll look into trying to under the rules files better. Frank
