Here is what I used: https://www.seeedstudio.com/Grove-High-Precision-RTC-p-2741.html
I'm using the Greens so it conveniently plugs in to the Grove connector. The lithium coin cell was not available at the local stores and I had to order via Amazon. This device uses 3.3V battery and it is plug-n-play with regards to the hardware. The Beagleboard distributions include a driver for it. In addition to confusion with logic voltages, the Linux ecosystem for RTCs is pretty confusing as well. The man pages have outdated or insufficient information. It was possible to get the RTC to work without touching the Device Tree. I've got the RTC to work and it is timing my irrigation control system reasonably well. I'm still not confident with what I am doing with the hwclock command. I've documented what I did in the PDF file page 26: https://github.com/Greg-R/irrigate-control/tree/master/doc/latex Good luck with the RTC and please share you results here! Regards, Greg -- 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 beagleboard+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/95bd10e9-2888-4a21-baa0-d2df2536cc8f%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
