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/CALHSORoqu8m9yZ2XUCimUznJkHEZ%2BjEoZtWyiuqywVUR0-TtwQ%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
