Ah, and I forgot to mention. Disconnecting power to the beaglebone is a necessity when shutting down the board. Otherwise, the beaglebone will occasionally be stuck in power limbo( what we talked about before ). Then will be unable to reset until someone physically disconnects / reconnects the power input to the beaglebone. Where the power is disconnected depends on whether you're externally powering via Geralds, and mine( for that matter ) preferred method. Or via a LiPO connected directly to the beaglebone / PMIC.
On Wed, Dec 21, 2016 at 7:14 AM, William Hermans <[email protected]> wrote: > On Wed, Dec 21, 2016 at 7:00 AM, Jason van Belzen < > [email protected]> wrote: > >> I understand that an external battery cape is the best solution. >> Do you know if the following is possible from linux perspective: >> >> - We run on battery and DC power >> - If we detect DC power loss, we close all running processes >> - Only kernel stays active >> - Kernel clocks itself down to a very low clockrate >> - Kernel checks periodically if power is restored >> - If power is restored, kernel gives itself a reboot >> >> Is something like this feasible or is this a very bad idea? >> >> Jason >> > > The problem is, no matter what, I think you're going to need some sort of > external interaction. I was the one who actually came up with the idea I > mentioned above around 3 or so years ago. I posted about it on the groups > here, and someone also implemented my same exact idea. Which I only > described at a high level. > > Anyway, what you're asking *may* be possible, but a lot of thought, and > perhaps some testing would have to be put into the idea. So apparently, > soon, power management will be put into the kernel, for the beaglebones . . > .What this means is that you should be able to hibernate, or suspend to > ram. What I'm unclear on personally though. Is how do we wake from this > state that we put ourselves into ? With an x86/x86-64 we have wake on lan, > possibly wake on wifi, etc. But all that uses power, power that may not be > in abundance. > > So I think the least complicated scenario is to use an external MCU, that > is able to detect when power is lost. The Beaglebone will also know when > the power is gone, and in fact, will either shutdown right away. Or if the > Debian package acpid is installed, the beaglebone will shut it's self down > in an orderly fashion. It then just becomes a case of having some form of a > battery(LiPO in our case connected to the battery test points ). If you > have an external battery that is able to provide 5v to the system. Then you > will probably want this MCU to check the AC input( or DC 5v if pre > regulated ), then connect a few isolated pins to the beaglebone for reset, > and a GPIO to initiate a beaglebone shutdown. > > But once again, you will need to put some thought into your design. Test > it, and discuss is with a few fairly bright people. To make sure did not > leave something out. I actually had to redesign my own software a few times > as a few things I did not think about came to light after testing. > -- 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/CALHSORojtSTxCmF9Gf_3oRqDM6Daz-Nr02_0uMuiAYVHSjA4gA%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
