IF you want power supply control like that. You will need a small
low power mcu like an msp430 running off of a small coin cell
to manage power.
On 6/19/2020 12:37 AM, [email protected] wrote:
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
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