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.
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.
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).
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.