Hi there
Some of my experiences with this Garmin and GPSD;
The Garmin isn't necessaryly set to defaults. Reset with: $PGRMO,,4
Then set the output pulse length to 200 ms; $PGRMC,,,,,,,,,,,,,9,
These should be terminated with a CrLf pair.
If connected directly to Minicom, the Garmin appears to be online once
per second. This is because the PPS is tied to DCD.
The circuit below can be used to avoid line status confusion;
Garmin Minicom
Male Female
9P 25P
RXD-----RXD 2 3
TXD-----TXD 3 2
GND-----GND 5 7
+-DCD 1 8
|
*-DTR 4 20
|
+-DSR 6 6
+-CTS 7 5
|
+-RTS 8 4
SH------SH
Start Minicom with '-o' to avoid sending an init string. Exit Minicom
with 'Ctrl-A,Z,Q' instead of 'X' to avoid a reset.
GPSD wants to change theses settings. Disable this in /etc/default/gpsd
with; DAEMON_OPTS="-b -n"
The NMEA data is off by some 170 ... 180 ms. This time keeps changing
all the time;
server 127.127.28.0 minpoll 4
fudge 127.127.28.0 time1 0.178 refid GPSa
server 127.127.28.1 minpoll 4 prefer
fudge 127.127.28.1 refid PPSa
NTPD want to make shore that GPS time source isn't talking nonsense.
This means you have to use an other time source as well.
Regards,
Rob
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