I’m kind of a noob so please forgive me:
How can I tell what GPIO pins are available for use as just regular gpio (write a 1 or a 0) on the J21 header?
What is “cat /sys/kernel/debug/gpio” telling me? And how do tell what is already set up as a gpio?
Please don’t point me to this: http://elinux.org/Jetson/Tutorials/GPIO as it hasn’t been very helpful for me. The output for the “cat /sys/kernel/debug/gpio” command isn’t shown in that tutorial so I have no clue what to look for. Also, I don’t know how to find out the gpio number used in software and how that links to the external header pin.
All I want is to turn on an external LED or two and sense button input on a button or two in a polling fashion. Hopefully I can stay in user space for all of this.
Like I said, I’m new to embedded Linux so, if possible, be as detailed as possible.