On 2/5/2014 7:02 AM, Robert P. J. Day wrote: > > in an embedded linux class i was teaching last week, the students > were all using beagle xMs (rev C), and we decided to experiment with > playing with the LEDs from user space. > > using the LED files under /sys/class/leds worked fine -- changing > the brightness, trigger and so on. but using this article as a basis: > > http://makezine.com/2009/02/03/blinking-leds-with-the-beagle-board/ > > we simply couldn't control the very same LED via gpio. we followed the > article, tried changing the LED trigger and so on, but nothing worked. > > can anyone with a BB xM (Rev C) verify whether or not that article > works for them? let me know which LED you pick, the GPIO pin number > you use, whether you need to change the trigger, etc. i'm sure i'm > missing something trivial, i'd just like to figure out what it is.
I don't have a BB xM, but which LEDs are you using? If you are trying to use the on-board LEDs that are assigned to things like CPU load and SD card access, you can't export the GPIO controlling that LED to user space because it's already "claimed" by the kernel. If you really want to drive the on-board LEDs, you need to edit the device tree so the GPIO is not claimed and the LEDs will disappear from /sys/class/leds/ The article uses a pin from the expansion connector, and from what I can tell the instructions should work assuming you use the proper GPIO pin number. -- Charles Steinkuehler [email protected] -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/groups/opt_out.
