I think what you are looking for is a bit lower level than the Kernel since you are looking to control the LEDs at power on. You may want to have a look at the Boot Sequence of the BBB and see if there is a place you can set this like you want. I'm not sure if you can do this from U-Boot though. https://elinux.org/EBC_Exercise_21a_Boot_Sequence
The other option is to set a cron job to turn off the LED at reboot considering you are already turning it on from the device tree. You may have to play with the timing to get it the way you want. However depending on what happens at boot, the timing could be off. Ex: https://billwaa.wordpress.com/2014/10/03/beaglebone-black-launch-python-script-at-boot-like-arduino-sketch/ Jon On Thu, Jan 7, 2021 at 9:15 PM ha ppay <andocn...@gmail.com> wrote: > Dear All > Does anyone have any ideas? > If you have any ideas on how to add LEDs, please let me know. > Regards, > > 2021年1月7日木曜日 10:37:31 UTC+9 ha ppay: > >> >> >> Hi >> Thank you for your reply, and the book's title! >> I checked table of contents of the book. >> Maybe, The Chapter 6 is that? >> I have experiences to control GPIO by python, and configure the device >> tree's defualt setting, write to value&direction file. >> I changed the GPIO Pin setting of device tree file to out&High for the >> LED turn on when bbb is powered on. >> But I can't find the method to turn off the LED in a few seconds. I tried >> to write python script to turn off the LED, and Systemd run the service >> script( using the After setting is "generic-board-startup.service ). >> but the timing is over 1minutes from the bbbw is powered on! >> I'm looking for the information of "as soon as bbb is powered on". >> I'm not familiar with embedded Linux. In particular, I have little idea >> about the behavior of driver-related programs. I'm wondering if the >> driver's program should do this. >> >> 2021年1月6日水曜日 22:39:14 UTC+9 iguana...@googlemail.com: >> >>> Hi! >>> Yes! I'm pretty sure that the Derek Molloy's "Exploring BeagleBone: >>> Tools and Techniques for Building with Embedded Linux" book has the >>> examples that you are looking for in various programming languages. >>> >>> El mié., 6 de ene. de 2021 10:16, BBBW User A <ando...@gmail.com> >>> escribió: >>> >>>> >>>> Hi everyone. >>>> >>>> I'm BBBW user. >>>> Could you tell me below question. >>>> >>>> Is there a wai to turn on the GPIO Controlled LED for a few seconds as >>>> soon as the bbbw is powered on, like user leds? >>>> and How to do it? >>>> >>>> Regards, >>>> >>>> -- >>>> 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...@googlegroups.com. >>>> To view this discussion on the web visit >>>> https://groups.google.com/d/msgid/beagleboard/364a2d6d-897f-4c72-99e0-4008f5504c77o%40googlegroups.com >>>> <https://groups.google.com/d/msgid/beagleboard/364a2d6d-897f-4c72-99e0-4008f5504c77o%40googlegroups.com?utm_medium=email&utm_source=footer> >>>> . >>>> >>> -- > 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. > To view this discussion on the web visit > https://groups.google.com/d/msgid/beagleboard/0a6c3263-ab7f-4b92-80a6-ad2f4cd5ff1dn%40googlegroups.com > <https://groups.google.com/d/msgid/beagleboard/0a6c3263-ab7f-4b92-80a6-ad2f4cd5ff1dn%40googlegroups.com?utm_medium=email&utm_source=footer> > . > -- 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. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/CAG99bkr9624bCTGtOeq%2BmZSsA43q3CSNTk%2BdAkYRadYTEueOPA%40mail.gmail.com.
