Add a pullup or just use a GPIO that defaults to high. Nothing is faster than that.
Gerald On Thu, Aug 6, 2015 at 9:28 AM, Axel Barkow <a...@barkow.name> wrote: > Hi, > > I need to set a GPIO output high as early as possible during the startup > and keep it active until the system shuts down. What I did so far: > > - Use GPIO 0.7 for testing > - Set GPIO0.7 high in python script automatically after startup -> GPIO > becomes high approx. 24s after power-on > - Modify device tree to set GPIO0.7 high -> GPIO becomes high approx. 9s > after startup > - Set GPIO0.7 high in u-boot scipt (/boot/boot.scr) -> GPIO becomes high > after approx. 3.5s, but becomes low again after approx. 6s > > My problem now is that the GPIO becomes low for approx. 3s after it was > set by u-boot and before the device tree. I guess I need to understand the > kernel boot process a little bit better. Any suggestion, where to start or > any hint where to look at? > > Regards > > Axel > > -- > 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. > -- Gerald ger...@beagleboard.org http://beagleboard.org/ -- 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.
