Hello Dennis, I much appreciate your reply. The point is that I have an external power supply that powers the BB and some other peripheral devices. So if I make shutdown -h the BB turns off but the external power supply still remains on. This is why I have a GPIO pin on the BB to turn off the external power supply. But I cannot use this pin if the BB itself is off! Hope it is clear now. Best rgds, G
Il giorno giovedì 18 giugno 2020 23:06:54 UTC+2, Dennis Bieber ha scritto: > > On Thu, 18 Jun 2020 10:58:55 -0700 (PDT), in > gmane.comp.hardware.beagleboard.user > [email protected] <javascript:> > wrote: > > >Hello everybody, > >I have a GP output of a Beaglebone Green that turns the power off when it > >is asserted by SW. It does its job well. > >However, I would like to power the Beagle off after having done a > shutdown > >(rather than turn it off suddenly). > >Is there any SW/HW trick to get this behavior? > > Are you talking about something that turns off an external power > supply? On the BBB, and BBAI, "shutdown -h now" ends with the circuits > behind the regulator chip being unpowered. > > Anything cutting power to the board itself likely needs to have a > sense > lead (maybe to one of the 5V header pins) which holds the power supply > "active", and opens when it loses the 5V. Of course, that also implies one > would need a momentary contact NO switch to the input of the power supply, > bridging to an always-on 5V source in order to "jump-start" the system > (hold down the NO switch to get the power supply to provide power to the > board, release switch when the header 5V pin feeds back to the power > supply > control). Of course, you may have to find some way to prevent any voltage > from the NO switch feeding back to the header pin. Maybe a pair of > transistors -- one transistor controlling the power supply input, with the > control lead shared by the output of the other transistor and the NO > switch; the second transistor controlled by the header 5V pin. IE: this > second transistor in/out is parallel with the NO switch. > > > -- > Dennis L Bieber > > -- 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 [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/83df0e35-6a5e-408f-902a-c3cd97453e49o%40googlegroups.com.
