[LinuxPPS] taming the gps18x

[Rodolfo Giometti]

On 16/03/18 10:26, Udo van den Heuvel wrote:
> Hello,
> 
> I am trying to make a Garmin GPS18x LVC work with my firewall.
> Another GPS18x *does* work, attached to this PC.
> I keep seeing 100's of ms of offset between the firewall and this
> workstation (and the rest of the world) in `ntpq -pn` output.
> 
> I also see:
> 
> # ppstest /chroot/ntpd/dev/pps0
> trying PPS source "/chroot/ntpd/dev/pps0"
> found PPS source "/chroot/ntpd/dev/pps0"
> ok, found 1 source(s), now start fetching data...
> source 0 - assert 1521192070.588686508, sequence: 150046 - clear
> 1521039630.201197096, sequence: 2
> source 0 - assert 1521192071.588741114, sequence: 150047 - clear
> 1521039630.201197096, sequence: 2
> source 0 - assert 1521192072.588592010, sequence: 150048 - clear
> 1521039630.201197096, sequence: 2
> source 0 - assert 1521192073.588552381, sequence: 150049 - clear
> 1521039630.201197096, sequence: 2
> source 0 - assert 1521192074.588503724, sequence: 150050 - clear
> 1521039630.201197096, sequence: 2
> source 0 - assert 1521192075.588455899, sequence: 150051 - clear
> 1521039630.201197096, sequence: 2
> source 0 - assert 1521192076.588526746, sequence: 150052 - clear
> 1521039630.201197096, sequence: 2
> ^C
> 
> Why isn't the clear timestamp incrementing but /is/ the assert timestamp
> incrementing?

Take a look at pps_event() function into linux/drivers/pps/kapi.c. Did you set 
PPS_CAPTURECLEAR or have you enabled clear events IRQ?

Ciao,

Rodolfo

-- 

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