Advanced users • pps0 not created with install of pps-tools

Hi all,
I'm trying to set up a pi 3 with an Adafruit GPS hat for a local NTP server. In general I'm following the excellent setup instructions in this blog: https://blog.networkprofile.org/gps-bac ... tp-server/

My basic problem is that no PPS device is set up in /dev . I think this should be automatic after installation of pps-tools, though I'm not 100% sure. The module is up and running and I get complete NEMA sentences from the GPS each second when I use 'cat /dev/serial0', and the hardware LED on the module is flashing to indicate a good satellite fix, so I don't believe this is a hardware problem with the module.

My basic setup is:
-OS: Raspbian lite 64 bit, kernel 6.6.56 v8+
-Hardware:
- Rasberry pi model 3b v1.2
- Adafruit ultimate GPS pi hat v3 (https://learn.adafruit.com/adafruit-ult ... i/overview)
- Software
-apt update and apt upgrade both executed (as of Oct-13-2024)
-pps-tools, gpsd, gpsd-tools, chrony, tcpdump and jq all installed successfully per the networkprofile.org instructions (I think only pps-tools is relevant, but include all here for completeness)
- per step 2 of the networkprofile.org instructions I removed lxde and avahi-daemon, since I only want this to be an NTP server

note: since this setup has no desktop, I've manually copied info from the bash on that pi here. Hopefully I haven't made any typos, but please do call any out and I'll confirm if its a transcription problem instead of an issue with my configurations.

I get through to step 5 of the networkprofile.org instructions (confirming that the PPS is connected), when I run into a problem. It appears that pps-tools is not fully configured after installation, as ppstest fails:

user@piname:~ppstest /dev/pps0
trying PPS source "/dev/pps0"
unable to open device "/dev/pps0" (No such file or directory)

I confirmed that my /boot/config.txt has the following:

dtoverlay=pps-gpio,gpiopin=4
enable_uart=1
init_uart_baud=9600

This is slightly modified from the networkprofile.org instructions as the GPS module there supported a higher baud, and used PGIO18. The Adafruit module has the PPS signal on GPIO4 and uses 9600 baud

I also confirmed that my /etc/modules has

pps-gpio

Checking the loaded modules I see:

user@piname:~lsmod | grep pps
pps_gpio 122880

but in other posts for different problems I see there should be a second line returned that looks something like:

pps_core##### # pps_gpio

which I am missing

checking dmesg I see:

dmesg | grep pps
[0.92244] pps_core: LinuxPPS API ver. 1 registered
[0.92272] pps_core: Software ver. 5.3.6 - Copyright 2005-2007 …

which again is missing lines that link pps_core with pps_gpio

I did see starquad's post from this past August (viewtopic.php?p=2246183&hilit=pps+pps0#p2246183), but they seem to have a different problem where pps0 exists, but is not connected properly to pps_gpio.

I'm hoping that someone can help me track down where I've gone wrong.

Statistics: Posted by TTomlin — Mon Oct 14, 2024 3:03 am

---