Hi A cheap GPS module and any of the nearly infinite number of sub $20 “demo boards” would make short work of looking at the pps, the time string out of the GPS and figuring out when it’s the top of the hour. I doubt it’s over 200 lines of code. I’m sure *somebody* will pop up with an example well below that. No need for an OS. No need for anything complex. There’s sure to be enough room even on a $2 board to include added stuff like real time clock driver and correcting the “local time” against GPS.
Bob > On May 2, 2016, at 5:36 PM, Nick Sayer via time-nuts <time-nuts@febo.com> > wrote: > > >> On May 2, 2016, at 9:51 AM, jimlux <jim...@earthlink.net> wrote: >> >> >> The real question is whether "cron" is timely enough. No matter, just write >> a script (or python) that reads time in a loop (and you can put a sleep in >> there) and pulses the GPIO when needed. >> > > A Raspberry Pi with nothing else on its plate will have a cron-to-shell > script latency easily under 100 ms, possibly under 10. > > If it were me and I were triggering a relay for some sort of external > circuit, I’d probably be happy it was on the right side of 500 ms. If I cared > more than that, then step 1 would be to do as others have suggested and come > up with a microcontroller + GPS solution instead of NTP + cron. Ironically, > that’d be around the same price (albeit more engineering work). > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.