Well, that depends on how skilled you are at modifying u-boot and the linux kernel?
In each case, modify the code that toggles the GPIO pin by printing text to the console when the GPIO you want is modified. You could always issue a kernel dump when that GPIO is modified, which will list the call sequence that causes the GPIO toggle. For the Kernel, I believe the code you want is in drivers/gpio/gpio-omap.c, but I haven’t looked at u-boot in a while, but it should be simple to find the equivalent code. If you had a decent JTAG emulator, you could simply set a breakpoint on the GPIO toggle and then look at the call stack to see which routing is responsible. Regards, John > On Mar 30, 2016, at 1:25 PM, M House <mikehous...@gmail.com> wrote: > > Hey everyone I'm still stuck as to why my beaglebone keeps changing the > polarity to 1 on boot. I can go in and manually change it but it always > resets after reboot. Should I maybe write a start up script to force the > polarity to 0? I'd rather find the root cause rather than a hack but at this > point anything that works is fine by me. > > Thank you > > On Saturday, March 19, 2016 at 11:30:58 PM UTC-7, M House wrote: > I'm doing a project right now that involves using a micro servo. One is on > port P8_13 and another on P9_14. > > Everytime I boot the beaglebone it gives me - error: Error enabling PWM > controls: Error: ENOENT, no such file or directory > '/sys/devices/ocp.3/bs_pwm_test_P9_14.15/polarity' > > When I check this file it shows a value of '1' inside of it. Where the same > file for P8_13 shows a zero. When I change the P9_14 polarity file to 0 the > servo works as intended. I'm really confused why the polarity is being set > to 1 every time I boot the beaglebone. This also happens if I move the servo > to P9_16. > > I did just upgrade from Debian 7.8 to 7.9 but I don't see how that would > change the GPIO behavior. > > > -- > For more options, visit http://beagleboard.org/discuss > <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 beagleboard+unsubscr...@googlegroups.com > <mailto:beagleboard+unsubscr...@googlegroups.com>. > For more options, visit https://groups.google.com/d/optout > <https://groups.google.com/d/optout>. -- 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 beagleboard+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
