[time-nuts] Designing an embedded precision GPS time server

[Nick Sayer]

I’ve just completed a project (off topic) with the ATSAMS70 chip and learned a lot in a relatively short time, and I really like the result.

I am considering a new project based on its cousin, the ATSAME70. The E70 has an Ethernet 10/100 MAC built in as well as the rest of the stuff the S70 has (USARTs, SD/MMC, AES-256, TRNG, high-speed USB… it’s quite nice), and Atmel Start (the software development framework I’ve been using) purports to have a ready-to-use IP stack (alas, no IPv6, but it’s a starting point at least).

Where I am going with this is I am considering designing a precision embedded NTP/PTP server. I’d connect one of the SkyTraq modules I’ve got piles of up to a GPIO and USART and the Ethernet port would provide NTP/PTP. The idea behind making it an embedded system would be to try and make it as accurate as it reasonably can be with the hope that (at least on the local segment) it would wind up being more accurate than a Pi Zero doing the same thing. At the very least, you’d expect such a thing to be a whole lot less hassle to set up, given decent firmware.

This may be a fool’s errand, certainly, but looking at it from here, I would think that such a design might offer accuracy in the microsecond range, but that’s just a tremendously uninformed guess at this point (and what does that accuracy mean to a peer that might itself be incapable of better than 2 orders of magnitude coarser?).

Anybody have any ideas or suggestions along these lines?