So I'm a bit unclear what yo uwant a real time clock for. If it's to keep proper time stamps on the beaglebone while logging, You do not need one. Part of your systemd startup service / script could call ntpdate to update the time from a atomic clock. *IF* the system has access to the internet.
If no internet, or you would like to keep time from the control MCU, Then one would probably need an external RTC. Which would complicate things a good bit, but is possible. On Thu, Feb 16, 2017 at 12:36 PM, William Hermans <[email protected]> wrote: > If you want the lowest possible power usage from the beaglebone, and using > something like, or akin to sleeping the system. You will need an external > processor( low power MCU ) involved. > > It would work something like this: > > > - The beaglebone is completely powered down > - the External MCU would toggle power, and reset lines on the > beaglebone. > - The beaglebone after boot through systemd would run a OneShot > service. > - This services calls a script that runs through a sequence of things > it must do for a single time period. Lastly, the board powers down. > - The MCU, has a timer loop than will toggle toggle the power and > reset lines on the beaglebone every X time period. > > While your at it, add psuedo watch dog functionality to your MCU, which > basically you've already done by following the above proceedures. Add an > I2C RTC to the board you made for this automated wake up system described > above. As the onboard beaglebone RTC functions, but only while it has power. > > On Thu, Feb 16, 2017 at 8:22 AM, Davide Aguiari <[email protected]> > wrote: > >> *Kernel*: Linux beaglebone 4.4.48-ti-r88 #1 SMP Sun Feb 12 01:06:00 UTC >> 2017 armv7l GNU/Linux >> *OS*: Debian 8.1 >> >> In order to get a low-power board, I get sensors data every 10min and I >> need to sleep meanwhile. >> I have an external RTC DS3231 with a SQW pin in order to setAlarm. I can >> plug it to a gpio and it changes its value when I want. >> >> What I would like is: >> 1) After the sampling, put the board in the highest low-power mode as >> possible (only the RTC running?) >> 2) Let the RTC wakup from suspension changing the gpio pin value >> >> I tried: >> root@beaglebone:/# echo standby > /sys/power/state >> >> The rtc set the gpio value from 1 to 0 but it doesn't wakeup. I think >> because I *don't have *the wakup option in /sys/class/gpio/gpio44/power. >> Right? How could I enable it? >> >> Is there a way to close the 3.3/5V output to the sensor when the device >> is sleeping and reopen it after wakeup? >> >> It this >> <http://processors.wiki.ti.com/index.php/AM335x_Power_Management_Standby_User%27s_Guide#GPIO_wakeup> >> guideline still good for my beaglebone green wireless? It tells to set >> >> echo uart0_rxd.gpio1_10=0x27,rising > standby_gpio_pad_conf >> >> but If I would set gpio P8_12? >> Something like: >> >> echo something.gpio44=0x??, falling > standby_gpio_pad_conf >> >> ??? >> >> Some tutorials speak about a GPIO0 use for wakeup. Which is in our BB? >> >> Is this the right way? >> >> Thank you for the support :D >> >> -- >> 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/ms >> gid/beagleboard/ce98bb67-36b6-4d9f-9e00-d9b55fb970e4%40googlegroups.com >> <https://groups.google.com/d/msgid/beagleboard/ce98bb67-36b6-4d9f-9e00-d9b55fb970e4%40googlegroups.com?utm_medium=email&utm_source=footer> >> . >> For more options, visit https://groups.google.com/d/optout. >> > > -- 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/CALHSORqmczfARCir09ay-kNfg4qrVMz8ZUdf8zGGm_PiZYfdjA%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
