[ntp:questions] pps breaks when nmea is enabled for ntpd

Richard Cagley rcagley at gmail.com
Sun Jun 16 00:54:49 UTC 2013


Very interesting. So, you just have this as your ntp.conf file?

server  127.127.20.1    mode 0  minpoll 4 maxpoll 4  prefer
fudge   127.127.20.1    flag1 1 flag3 1 refid PPS

When I do this I think only the GPS/127.127.20.0 line shows up in the
output. How do I know PPS is working? With just these two lines in my
ntp.conf file should I expect two lines in the output of ntpq -p?

I'll have to confirm this when I get co-located with the hardware tomorrow.




On Sat, Jun 15, 2013 at 10:10 AM, David Taylor <
david-taylor at blueyonder.co.uk.invalid> wrote:

> On 15/06/2013 02:03, Richard Cagley wrote:
>
>> I have a TI DM8168 processor and a u-blox gps.
>>
>> If I enable an internet server and pps, then pps works great
>>
>> server clock.redhat.com iburst prefer minpoll 4 maxpoll 4
>> server 127.127.22.0 minpoll 4 maxpoll 4
>> fudge 127.127.22.0 flag3 1
>>
>> However, if I add an NMEA server to my ntp.conf file like this
>>
>> server 127.127.20.0 mode 1
>> fudge 127.127.20.0 flag1 1
>> server 127.127.22.0 minpoll 4 maxpoll 4
>> fudge 127.127.22.0 flag3 1
>>
>> then pps stops working. I can kill ntpd and ppstest no longer works. It's
>> as though nmea is clobbering the serial port.
>>
>> It sorta feels like this, but there was no resolution
>> http://lists.ntp.org/**pipermail/questions/2011-**September/030347.html<http://lists.ntp.org/pipermail/questions/2011-September/030347.html>
>>
>> Can anyone help me. I've really been struggling with this.
>>
>
> On my FreeBSD system, to enable PPS on the type 20 (NMEA) driver, I just
> added flag1 and flag3 set to 1:
>
> ______________________________**___________
> server  127.127.20.1    mode 0  minpoll 4 maxpoll 4  prefer
> fudge   127.127.20.1    flag1 1 flag3 1 refid PPS
> ______________________________**___________
>
> It's running ntpd 4.2.7p368, and does have Internet servers as well.
> Excuse ant#y wrap....
>
> C:\Users\David>ntpq -pn pixie
>      remote           refid      st t when poll reach   delay   offset
>  jitter
> ==============================**==============================**
> ==================
> o127.127.20.1    .PPS.            0 l    3   16  377    0.000   -0.002
>  0.002
>  uk.pool.ntp.org .POOL.          16 p    - 1024    0    0.000    0.000
> 0.002
> +192.168.0.1     .PPS.            1 u   29   64  377    0.150    0.029
>  0.041
> +192.168.0.2     .PPS.            1 u    3   64  377    0.233    0.028
>  0.027
> -91.212.90.20    89.36.197.2      3 u 1057 1024  377   18.130    3.258
>  4.000
> -87.117.251.45   242.195.192.75   3 u  953 1024  377   19.668    2.265
>  4.685
> -109.123.121.128 158.43.128.33    2 u   53 1024  377   22.207   -9.700
> 11.722
> -85.119.80.233   193.47.164.28    3 u  323 1024  377   18.982    3.549
>  8.302
> -94.125.132.7    195.66.241.10 2 u  876 1024  377   20.969    2.886  6.127
> +94.125.129.7    195.66.241.10 2 u  280 1024  377   19.508    3.565  1.376
>
>
> I don't know whether that helps.
> --
> Cheers,
> David
> Web: http://www.satsignal.eu
>
>
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