5 ms·
The Raspberry Pi as a Stratum-1 NTP Server
- stephen-mw 8y agoI just built one of these. It's fun to have a little computer that can synchronize highly accurate time without an internet connection by listening to things in outer space! I built an auto-install script that anyone here is welcome to use or reference[1]. If you know what you're doing, just change the GPIO pin to your PPS input and fire away. Unlike the author I used Chrony instead of NTP. It's lighter-weight and much easier to configure with a PPS/GPS reference clock. The GPS chip I used was an ATGM336H, which can be had for less than $8 on ebay. I'm able to lock consistently 11 satellites from my desk[2] Keep in mind the Pi has no hw RTC. If you're doing this for fun spend a few more bucks and buy an rtc chip from ebay so you don't drift considerably between being powered off. 1. https://github.com/stephen-mw/raspberrypi/blob/master/roles/stratum_1_timeserver/install https://github.com/stephen-mw/raspberrypi/blob/master/roles/... 2. https://www.ebay.com/sch/i.html?_from=R40&_nkw=ATGM336H&_sacat=0&LH_TitleDesc=0&LH_BIN=1&_sop=15 https://www.ebay.com/sch/i.html?_from=R40&_nkw=ATGM336H&_sac...
- homero 8y agoI built a nixie tube clock like that with a gps receiver, it works amazingly
- epynonymous 8y agothis is pretty cool. i was looking at your case, could you tell me the exact model case you were using? i couldn't find the exact model on modmypi. also, here's a writeup i did on my experiences creating something with an rpi 3 model b+: https://github.com/stephenhu/written/blob/master/raspberrypi.md https://github.com/stephenhu/written/blob/master/raspberrypi...
- glenneroo 8y agoI had one of these running with a 10 meter cable to the window so the receiver could get enough satellites. After 24/7 for about a year it just died and I haven't had time to figure out what's wrong. Lights blink but it's not reachable via ping, ssh or scp. HDMI output shows nothing. I had to move on to other projects, so I gave up and assumed I either got hacked or I hit the cheap-SD-card problem of corruption that seems to plague other users running their Pi continuously for longer periods. I've started buying SanDisk's "High Endurance" microSD cards hoping it will mitigate any such issues in the future, but I haven't had time to get the NTP set up again... I really should have cloned the image. I think the hardest part was finding a case with space for the GPS hat[0] with an open end for the coax connector. The hat sits a bit crooked because of something bulbous on top (condensator?). [0]: https://store.uputronics.com/index.php?route=product/product&product_id=81&search=GPS+Expansion+Board+ https://store.uputronics.com/index.php?route=product/product...
- gsich 8y agoSwitch to network boot with NFS as storage. Much faster (compared to most "cheap" SD cards) and more reliable.
- mlichvar 8y agoAnother possibility to improve reliability with SD cards is to use a distro that is designed to not make any writes to the storage in normal operation. I have some NTP servers running on OpenWRT and they work great.
- glenneroo 8y agoAlong a similar vein (if sticking with Raspbian, et al distros is important), you can e.g. disable swap and journaling, using ramdisk for logs, etc. as well as keeping lots of free space available for wear-leveling and a few other ideas: https://raspberrypi.stackexchange.com/questions/169/how-can-i-extend-the-life-of-my-sd-card https://raspberrypi.stackexchange.com/questions/169/how-can-...
- stephen-mw 8y agoCheck out my install script linked earlier. If you already have the GPS unit attached and tested, you could probably be up and running again in a few minutes (make sure to change the GPIO pin in the script to your PPS pin).
- steve19 8y agoI wonder how much the rpi foundation would need to sell a pi if it included 32gb of storage. I would gladly pay not to feel like I'm playing roulette with my microsd.
- jon-wood 8y agoTake a look at Resin’s Project Fin, which is designed for IoT deployments - it runs off a Pi Compute Module. https://resin.io/blog/introducing-project-fin-a-board-for-fleet-owners/ https://resin.io/blog/introducing-project-fin-a-board-for-fl...
- tramtrist 8y agoThey still haven't separated the USB/Ethernet Bus :/
- makomk 8y agoThis is also possible with the Orange Pi/NanoPi boards which have actual Ethernet that doesn't go over USB, though I don't think there's such a good writeup of how to do that.
- berbec 8y agoThis would be a perfect case for a NanoPi Neo. [1] It's designed to be ultra-tiny and run headless. It's also $13. I find FriendlyElec's board better designed and supported than Orange by a bit and miles above the Banana folks. 1: https://www.friendlyarm.com/index.php?route=product/product&path=69&product_id=132 https://www.friendlyarm.com/index.php?route=product/product&...
- jwildeboer 8y agoMaybe add [2012] to the title, dear mods?
- TheRealDunkirk 8y agoAnd maybe a trigger warning about the FrontPage 97 theme...
- gsich 8y agoAre there performance differences regarding Pi 1/2/3?
- abraham_lincoln 8y agoYes, very much so.
- gsich 8y agoDo you have some numbers?
- mwambua 8y agoThe biggest factor is that each generation of the Pi has gotten a better processor (700Mhz single-core in the original Pi to a 1.4Ghz quad-core in the 3B+). There are also a number of detailed benchmarks out there if you bother to Google it.
- gsich 8y agoEspecially in the context of a stratum 1?
- skykooler 8y agoWhat is the use case for microsecond-accurate timekeeping?
- onemoresoop 8y agoit's mostly about synchronization between systems
- cremp 8y agoI've done it; and my primary argument to family and friends is time attack vectors. The real reason though, is because I can, and I like saying my computers are more accurate and precise than their phones.
- cremp 8y ago> Configuring Wi-Fi That alone will negate any benefit of running a stratum 1. You lose the precision and accuracy over wifi. Jitter on intranet with the pi as a timesource would be magnitudes greater than the GPS link.
- johnklos 8y agoNot exactly. Sometimes it's more helpful to have a local time source that you know is accurate but has a little jitter than to have a remote time source with intermittent Internet.
- bestouff 8y agoRPi's ethernet-over-USB is no better: it aggregates packets to compensate for limited bandwitdh, incurring killer jitter.
- Jaruzel 8y agoOff topic: I love this couples website. If you click through to the homepage they've got lots of stuff to browse. Yes, it maybe old-style, but it's these sort of sites that the internet was originally built on. It's a real shame that they are becoming a dying breed.