Difference between revisions of "NTP"
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==Time synchronisation from GPS== | ==Time synchronisation from GPS== | ||
* You will need the "real" NTP daemon, not the Busybox one. | * You will need the "real" NTP daemon, not the Busybox one. | ||
| − | * | + | * Edit config file (''/etc/ntp.conf''): |
<pre class="apf"> | <pre class="apf"> | ||
# Allow only time queries, at a limited rate, sending KoD when in excess. | # Allow only time queries, at a limited rate, sending KoD when in excess. | ||
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* ''mode 17'' is for 9600 bauds GPS providing GPRMC frames | * ''mode 17'' is for 9600 bauds GPS providing GPRMC frames | ||
| − | * To create /dev/gpsX (GPS is connected to UART2): | + | * To create /dev/gpsX (here GPS is connected to UART2): |
<pre class="apf"> | <pre class="apf"> | ||
# ln -sf /dev/ttymxc1 /dev/gps0 | # ln -sf /dev/ttymxc1 /dev/gps0 | ||
Revision as of 20:11, 9 November 2016
From https://en.wikipedia.org/wiki/Network_Time_Protocol, "Network Time Protocol (NTP) is a networking protocol for clock synchronization between computer systems over packet-switched, variable-latency data networks." Practically, it allows you to have current time/date on your APF even if your don't have an RTC (you will need an Internet connection or a GPS ;-)).
Get current Time from Internet
# ntpd -nqp 217.147.208.1
Time synchronisation from GPS
- You will need the "real" NTP daemon, not the Busybox one.
- Edit config file (/etc/ntp.conf):
# Allow only time queries, at a limited rate, sending KoD when in excess. # Allow all local queries (IPv4, IPv6) restrict default nomodify nopeer noquery limited kod restrict 127.0.0.1 restrict [::1] server 127.127.20.0 mode 17 minpoll 4 maxpoll 4 prefer fudge 127.127.20.0 flag3 1 flag2 0 flag1 1 time1 0.0
- 127.127.20.0 means: "use /dev/gps0 and parse it as NMEA to get time" (See [1]).
- mode 17 is for 9600 bauds GPS providing GPRMC frames
- To create /dev/gpsX (here GPS is connected to UART2):
# ln -sf /dev/ttymxc1 /dev/gps0
- To launch ntpd:
# /usr/sbin/ntpd -g -c /etc/ntp.conf
