问题
OK I am stumped and its possible I have just not had enough experience with android, so I dont know which permissions to use.
I have recompiled the android kernel to expose the gpio pins I need, maybe I need to do something in the kernel to solve my problem... basically at this point i have no idea
I can open adb shell and go /sys/class/gpio/export 141 and get the gpio folder and its files (value,direction,etc).
and when I am in the adb shell I can set the direction and values using echo out>direction;echo 1>value;echo 0>value; and everything works great , the pin drives low or high.
I put the export 141 into init.rc and now that gets exported on startup.
If I try to access the value file from within my kivy app it crashes and says permissions denied (to be expected)
If I chmod 0666 to both the direction and value it sucessfully updates the permissions in the file sys.
-rw-rw-rw- root root 4096 2013-10-01 06:59 value
-rw-rw-rw- root root 4096 2013-10-01 06:59 direction
now when i try to write to the files from kivy(python) I get [Errno 1] Operation not permitted I get the same result if I try to chown the file to my apps user or to system. I feel like Ive tried almost everything and cant seem to write to /sys/class/gpio/gpio141/value or direction
回答1:
OK I finally figured it out... right before I pulled out all my hair.
so for whatever reason it would crash and die when I would call
with open("/sys/class/gpio/gpio141/value","w") as f:
f.write("1")
however if I called it as
os.system("echo 1>/sys/class/gpio/gpio141/value")
it worked fine.
Im still not sure why I would get operation not permitted when I would try to open it as a filehandle
来源：https://stackoverflow.com/questions/19170689/accessing-gpio-from-within-kivy-android-app