BeagleBone Blue: Hack to boot when DC power is restored to DC Jack?

[Louis L. Whitcomb]

Colleagues,

I have an embedded application for a beaglebone blue in which it is a
NTP client and provides a precision pulse-per-second (PPS) TTL output to
an acoustic modem, all deep inside a pressure housing in an underwater
robotic vehicle
(https://www.whoi.edu/what-we-do/explore/underwater-vehicles/nereid-under-ice).

Our C code running on the beaglebone blue monitors the DC Jack
voltage, and executes a clean shutdown if DC Jack voltage is lost for a
period of time (system("sudo shutdown --poweroff 0 Shutting down due to
loss of DC power")).

Unfortunately for us, when power is restored to the DC Jack, the
beaglebone blue CPU does not power on automatically. The OSD3358 powers
up when the "POW" button is pressed, which pulls down the PMIC_IN_PB_IN
pin D20 on the OSD3358, but of course this button is inaccessible in our
application.

Does anyone have a tested hardware hack that will cause the
BeagleBone Blue to automatically reboot when power is restored to the DC
jack? I am thinking maybe a capacitor in series with a resistor between
DC jack and the based of an NPN transistor, whose emitter is grounded,
and collector momentarily pulls down PMIC_IN_PB_IN when DC power is
restored to the board. But there may be simpler solutions. Any
thoughts are welcome.

Thanks and Best Regards,

-Louis

--
-------------------------------------------------------------
Louis L. Whitcomb, Ph.D.
Professor, Department of Mechanical Engineering
115 Hackerman Hall, 3400 N. Charles Street
Johns Hopkins University, Baltimore, MD, 21218-2681
l...@jhu.edu, 410-516-6724, https://dscl.lcsr.jhu.edu
-------------------------------------------------------------

[gra...@flex-radio.com]

Louis:

There are multiple families of a type of IC known as a Power-On reset IC, or supervisory reset IC

They wait for a Voltage to appear above a threshold, and remain stable for some period, then send a reset output for a predetermined time.

If you go to the On Semi site, and search on "Power On Reset", you will get hits about ten different ICs.

Check out the MAX809 as an example

TI has a selector page, see

http://www.ti.com/power-management/supervisor-reset-ic/overview.html

If you go to the On Semi site, and search on "Power On Reset", you will get hits about ten different ICs.

Check out the MAX809 as an example

They are generally cheap and small, and many require no support or glue parts other than a bypass cap, if their default Voltages and times work for you.

--- Graham,

[Louis Whitcomb]

Dear Graham,

   Thanks for your reply!  Yes, I am aware of power-on reset ICs, as well as simple power-on reset circuits with discrete components.  I was hoping that the designers of the BeagleBone Blue, or experts on the OSD3358, might be aware solution that was already designed into the system (cut a trace, short an input, burn a fuse, etc).  

   Thanks and Best Regards,

 

    -Louis

[Akshay]

Hi Louis,

Did you manage to find a solution to this? We are trying to solve a similar issue with the Beagleboard x15, to boot it up on receiving 12V power from the DC jack, without the need for pressing the power button.

Thanks!
Akshay

[Robert Nelson]

On Tue, Jun 25, 2019 at 1:14 PM Akshay <maker...@gmail.com> wrote:
>
> Hi Louis,
>
> Did you manage to find a solution to this? We are trying to solve a similar issue with the Beagleboard x15, to boot it up on receiving 12V power from the DC jack, without the need for pressing the power button.

On the x15, that is J5..

https://github.com/beagleboard/beagleboard-x15/blob/master/BEAGLEBOARD_X15_REV_B1.pdf

Regards,

--
Robert Nelson
https://rcn-ee.com/

[Louis Whitcomb]

I did not find a hack for the BeagleBone Blue.  Instead I used the ubuntu overlayroot package (https://packages.ubuntu.com/xenial/admin/overlayroot) to bring up the BBBlue with a read-only file system so that power can be removed while linux is running without corrupting the file system.  I found this post by Rovert Nelson to be very helpful: https://forum.digikey.com/t/about-the-datetime-and-soft-power-off-for-bbb/2985/3

  Best Regards,

 

   -Louis