Re: [chrony-users] Re: Any nice example of chrony, WWVB, Raspberry Pi ?

[Mike Collins <mocallins@xxxxxxxxx>]

[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, infection.many550@xxxxxxxxxxx <infection.many550@xxxxxxxxxxx> 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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