[time-nuts] GPS module recommendation for Pi timing

[Brian Lloyd]

I have an application where I need to synchronize the internal TOD RTC in a
raspberry pi and need to pick a GPS module. We are building our own
hardware but still using the Pi so interconnection will be via GPIO/serial.
We won't try to use USB.

This is not an NTP application. These units will be in the field and will
most likely not have Internet access. I need their clocks to be pretty
close. I am shooting for 1ms ... if possible.

The new M9F and M9T modules from Ublox are a bit pricey. The M8T is a bit
more reasonable. OTOH I realize there are limits to how tightly I can
control the Pi's RTC and will run into diminishing returns, so even the M8T
might be overkill.

Has anyone here figured out what the reasonable limit is for timing on a
Pi, and what makes sense for a timing module for an application like this?

Thanks.

-- 



Brian Lloyd
706 Flightline
Spring Branch, TX 78070
brian at lloyd.aero
+1.210.802-8FLY (1.210.802-8359)