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

[David Taylor]

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
>
> 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