Actually, my initial desire for creating the cape was to have a battery-powered Linux node that could power on, perform some task, and then power itself back off and consume very little power in between. So, the cape will selectively power up the BB on a timeout, an external signal, button press, or DC power restoration. When the BB powers itself down and 3V3 goes away, the cape cuts all power to the BB and then waits for another event. While running, Linux can monitor DC power present and the battery voltage and current through an INA219 on the cape.
Everyone kept asking about a charging circuit and UPS functionality. So, I added that. The charger is a nice little part that does "dynamic power path management" and will augment the DC supply from the battery if necessary and charge the battery when excess DC current is available. The charger will always run when DC is present so you could plug a solar panel into the cape's DC jack and now the node doesn't require a battery change (I *do* plan on using that feature!). So, for the shutdown, the cape itself doesn't do anything since that's a software issue. But since DC power status is reported through a status register over I2C, I used that in a bash script while toying with a "podcast car computer". I haven't spent much time on it but it definitely turns itself on and off with the car. I guess the other option would be a kernel module that monitors power good and initiates the shutdown... -Ron On Friday, May 9, 2014 11:17:22 PM UTC-5, ags wrote: > > Yes, I did find those. From what I read, it seems that both aim at > allowing the BBB to run when there is no mains power. In my application, I > don't have a need for the BBB to maintain functionality when there is no > power (other than battery). I'm simply interested in ensuring a safe > shutdown sequence when power is removed. It seems from both posts that this > has still not been addressed. These methods are focused on keeping the BBB > running on battery power; however, when the battery discharges, I saw no > discussion about an orderly shutdown occurring. I'm looking for an > immediate, but orderly shutdown, and don't care about sustaining operation > (beyond a safe shutdown) when power is removed. > > > > On Friday, May 9, 2014 7:56:01 AM UTC-7, Ron B. wrote: >> >> Have you seen this >> post<http://www.element14.com/community/community/knode/single-board_computers/next-gen_beaglebone/blog/2013/08/10/bbb--rechargeable-on-board-battery-system>and >> discussion? >> >> Personally, I went the full >> cape<http://andicelabs.com/beaglebone-powercape/>route because it gave me >> more flexibililty for power-up events as well as a >> very low power (~80uA) power off state. >> >> -Ron >> >>> >>>> -- 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]. For more options, visit https://groups.google.com/d/optout.
