<div dir="ltr"><p class="MsoNormal"> </p>
<p class="MsoNormal">Could you please help me with the following problem ?</p>
<p class="MsoNormal">Our board supports PPS & NTP . I connect & define
the Garmin GPS as the NMEA reference clock . Unfortunately when I add the
atom reference clock to ntp in order to receive pps , </p>
<p class="MsoNormal">after sometime NMEA & ATOM(pps) clocks marked as
falsetick servers . I see that it can related to the jitter and can be fixed by
setserial low_latency . But out UART doesn’t support this flag . </p>
<p class="MsoNormal">Therefore could you please explain how I can fix pps
falsetick problem witout use setserial . Our configuration is following :</p>
<p class="MsoNormal">Ntp configuration (ntpd 4.2.6p5) :</p>
<p class="MsoNormal"><span style="color:rgb(31,73,125)">server 127.127.1.0 #lo server</span></p>
<p class="MsoNormal"><span style="color:rgb(31,73,125)">fudge 127.127.1.0 stratum 7</span></p>
<p class="MsoNormal"><span style="color:rgb(31,73,125)"> </span></p>
<p class="MsoNormal"><span style="color:rgb(31,73,125)">restrict 127.127.1.0 noquery
nomodify notrap</span></p>
<p class="MsoNormal"><span style="color:rgb(31,73,125)">server 127.127.20.0 minpoll 4
maxpoll 4 iburst #NMEA Server </span></p>
<p class="MsoNormal"><span style="color:rgb(31,73,125)">server 127.127.22.0 prefer </span></p>
<p class="MsoNormal"><span style="color:rgb(31,73,125)">fudge 127.127.22.0 flag3 1 refid
PPS</span></p>
<p class="MsoNormal"><span style="color:rgb(31,73,125)"> </span></p>
<p class="MsoNormal">ntpq -p</p>
<p class="MsoNormal"><span style="color:rgb(31,73,125)">
remote
refid st t when poll reach
delay offset jitter</span></p>
<p class="MsoNormal"><span style="color:rgb(31,73,125)">==============================================================================</span></p>
<p class="MsoNormal"><span style="color:rgb(31,73,125)">*LOCAL(0)
.LOCL. 7
l 5 64 377
0.000 0.000 0.031</span></p>
<p class="MsoNormal"><span style="color:rgb(31,73,125)">xGPS_NMEA(0)
.GPS. 0
l 4 16 377 0.000
-63.203 5.256</span></p>
<p class="MsoNormal"><span style="color:rgb(31,73,125)">xPPS(0)
.PPS. 0
l 3 64 377 0.000
-347.47 7.428</span></p>
<p class="MsoNormal"><span style="color:rgb(31,73,125)">root@am335x-evm:/dev# ntpdc</span></p>
<p class="MsoNormal"><span style="color:rgb(31,73,125)">ntpdc> kerninfo</span></p>
<p class="MsoNormal"><span style="color:rgb(31,73,125)">pll
offset: 0 s</span></p>
<p class="MsoNormal"><span style="color:rgb(31,73,125)">pll
frequency: 0.000 ppm</span></p>
<p class="MsoNormal"><span style="color:rgb(31,73,125)">maximum
error: 0.013456 s</span></p>
<p class="MsoNormal"><span style="color:rgb(31,73,125)">estimated
error: 1e-05 s</span></p>
<p class="MsoNormal"><span style="color:rgb(31,73,125)">status:
2007 pll ppsfreq ppstime nano</span></p>
<p class="MsoNormal"><span style="color:rgb(31,73,125)">pll time constant:
6</span></p>
<p class="MsoNormal"><span style="color:rgb(31,73,125)">precision:
1e-09 s</span></p>
<p class="MsoNormal"><span style="color:rgb(31,73,125)">frequency tolerance: 500
ppm </span></p>
<p class="MsoNormal"><span style="color:rgb(31,73,125)"> </span></p>
<p class="MsoNormal"><span style="color:rgb(31,73,125)"> </span></p>
<p class="MsoNormal">root@am335x-evm:/dev# ntptime</p>
<p class="MsoNormal"><span style="color:rgb(31,73,125)">ntp_gettime() returns code 0
(OK)</span></p>
<p class="MsoNormal"><span style="color:rgb(31,73,125)"> time
d6dd71e6.aaf4cf0c Wed, Mar 26 2014 15:33:58.667, (.667798707),</span></p>
<p class="MsoNormal"><span style="color:rgb(31,73,125)"> maximum error 23956 us,
estimated error 10 us, TAI offset 0</span></p>
<p class="MsoNormal"><span style="color:rgb(31,73,125)">ntp_adjtime() returns code 0
(OK)</span></p>
<p class="MsoNormal"><span style="color:rgb(31,73,125)"> modes 0x0 (),</span></p>
<p class="MsoNormal"><span style="color:rgb(31,73,125)"> offset 0.000 us,
frequency 0.000 ppm, interval 1 s,</span></p>
<p class="MsoNormal"><span style="color:rgb(31,73,125)"> maximum error 23956 us,
estimated error 10 us,</span></p>
<p class="MsoNormal"><span style="color:rgb(31,73,125)"> status 0x2007
(PLL,PPSFREQ,PPSTIME,NANO),</span></p>
<p class="MsoNormal"><span style="color:rgb(31,73,125)"> time constant 6,
precision 0.001 us, tolerance 500 ppm,</span></p><p class="MsoNormal"><span style="color:rgb(31,73,125)"><br></span></p><p class="MsoNormal"><span style="color:rgb(31,73,125)"><br></span></p><p class="MsoNormal"><span style="color:rgb(31,73,125)">Regards</span></p>
<p class="MsoNormal"><span style="color:rgb(31,73,125)">Arthur</span></p></div>