On Thu, 18 Jun 2020 10:58:55 -0700 (PDT), in
gmane.comp.hardware.beagleboard.user
[email protected] 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
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