[piclock]:</home/pi/> cat /etc/default/gpsd
# Devices gpsd should collect to at boot time.
# Start the gpsd daemon automatically at boot time
START_DAEMON="true"
# They need to be read/writeable, either by user gpsd or the group dialout.
DEVICES="/dev/pps0"
# Other options you want to pass to gpsd
#GPSD_OPTIONS=""
GPSD_OPTIONS="-n"
# Automatically hot add/remove USB GPS devices via gpsdctl
USBAUTO="true"
And the pertinent part from chrony.conf:
refclock PPS /dev/pps0 refid PPS
refclock SHM 0 refid GPS precision 1e-1 offset 0.200 delay 0.6
On Tuesday, October 22, 2024 at 10:44:57 AM CDT,
[email protected] <[email protected]> wrote:
On Tue, Oct 22, 2024 at 09:28:54AM GMT, Miroslav Lichvar wrote:
> These values are bad. A well-working PPS source should show much
> better skew and std dev. A rpi should be capable of getting below 1
> ppm and 100 microseconds. I suspect there is still something wrong
> with your setup. Maybe some noise is picked on the GPIO.
Here are mine:
3+0 ~$ chronyc -N sourcestats
Name/IP Address NP NR Span Frequency Freq Skew Offset Std Dev
==============================================================================
PPS0 10 7 145 -0.000 0.010 -1ns 292ns
RPi 3B + bookworm, Uputronics GPS hat
--
Ian
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