utterances-bot commented 3 years ago

Building a GPS based time server | Jacob Deane - geek, photographer, engineer

Time is an illusion. Lunchtime doubly so. This is a rough guide of how to build a super accurate NTP time server on a raspberry pi using GPS as the primary time source.

https://www.jacobdeane.com/iot/2020/building-a-gps-based-time-server/

jepolch commented 3 years ago

Thank you very much for this excellent guide. I've followed others, but 'gpsmon' didn't show PPS and 'ntpshmmon' didn't show any output. You included a few config items the others seem to have overlooked. My NTP server is now whole. Thanks!

nar1117 commented 2 years ago

This is one of the best pi write-ups I've ever used! You seriously covered all the bases, explained the process, and provided great explanations, all without wasting any time. Thank you!

bt-modbox commented 2 years ago

Did you require an additional GPIO header extender for the POE+ hat? Some additional assembly pics would be great. Like the article!

alexbromberek2020 commented 2 years ago

I would love to know what case you used for this

bt-modbox commented 2 years ago

I completed a similar build to this. So appreciate the writeup. @alexbromerek2020 I personally used HighPi Raspberry Pi 2/3 Case - clear. I had to make some mods to account for the GPS hat (attached the top with screws + standoffs). The case being "clear" allows for the LEDs to be visible.

alexbromberek2020 commented 2 years ago

i cant get cat /dev/ttyAMA0 to work i have this https://v3.airspy.us/product/upu-rpi-gps-rtc/ with a PI 3B

alexbromberek2020 commented 2 years ago

never mind I have it working I just with there was a web interface to see that it is seeing

bt-modbox commented 2 years ago

CLI only that I'm aware.

maxall41 commented 2 years ago

I have a weird issue where it will work for the first few seconds when booted and gpsmon will show all the info but then it will break the serial port will stop sending any data and gpsmon wont show anything either. Does anybody know why this might be happening?

bt-modbox commented 1 year ago

You may want to check the UART steps to make sure there's no conflicts. I haven't encountered this and have been running two of these GPS Pi's non-stop for over 6mo's.

nathanwosborn commented 1 year ago

Is it advisable to enable/use the RTC portion of the hat? I have seen ntp get confused if the local time is too far from network time.

symgryph commented 10 months ago

as an FYI, I also did this with some modifications (I liked the secure ntp option nts invented in 2020 which uses proper tls negotiation and gets rid of amplification attacks: https://grav.munn.me/my-blog/how-to-setup-a-stratum-1-secure-ntp-server-ntps ) I also note that there is a nice link in there for setting the RTC with the board and manuals. Finally remember that the board in question has an RTC, which is also covered in the manual: https://store.uputronics.com/files/Uputronics%20Raspberry%20Pi%20GPS%20RTC%20Board%20Datasheet.pdf

symgryph commented 10 months ago

I still haven't finished the NTPS section, but I am working on it. Your write up is one of the best and it actually works. Its kind of fun. Here is my resutls (after being up for 1 hour on pi)

ntpq -p -u
     remote                                   refid      st t when poll reach   delay   offset   jitter
=======================================================================================================
*SHM(1)                                  .PPS.            0 l   35   64  377      0ns 209.03µs 15.723µs
-SHM(0)                                  .GPS.            0 l   34   64  377      0ns -55.61ms 346.75µs
 us.pool.ntp.org                         .POOL.          16 p    -  256    0      0ns      0ns    954ns
-wylief.dev                              173.214.173.170  3 u  102  128  377 24.784ms 2.9387ms 1.1709ms
-143-42-229-154.ip.linodeusercontent.com 47.187.174.51    2 u   94  128  377 15.537ms 2.0359ms 216.78µs
-owners.kjsl.com                         17.253.16.253    2 u   49   64  377 64.280ms 1.0555ms 175.32µs
+hc-007-ntp1.weber.edu                   .PPS.            1 u   38   64  377 79.035ms 344.84µs 207.14µs
-time.walb.tech                          104.155.144.4    3 u  126  128  277 22.614ms 4.0519ms 5.1286ms
-dns-e.ns4v.icu                          72.30.35.89      3 u  125  128  377 55.724ms -1.992ms 342.63µs
+clock.sjc.he.net                        66.220.9.122     2 u   41   64  377 64.136ms 1.5171ms 351.33µs

exrith commented 2 weeks ago

im on step 2 and im getting this. Im assuming its not working got any ideas?

@NTP1:~ $ cat /dev/ttyAMA0 ã5A&J`¬c$#dTÁCÁüâ}ýA4 acb0c#Hcc=b,#S¦!üã5A&J¬c$#dTÁCÁüà}ýA4 ic¨b¤# ° P ÿ$4Id"A à}ÝA4 ic¨b1ÇcYb cm1H¤{ Í,êc*S%p 0jÍ c#Llc-#UBIám1X¤# d,CáBI}0Å#,4tBdBYà}ÝE4 ic¨`Á9D9NIc)i `ÈPû$61)eÃa,¬c$+^C *@NTP1:~ $

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Building a GPS based time server | Jacob Deane - geek, photographer, engineer