[time-nuts] Connecting my Oncores

Matthew Smith matt at smiffytech.com
Tue Apr 1 23:56:56 EDT 2008

Quoth Hal Murray at 2008-04-02 14:08...
>> My manual suggests you need to send
>> @@Ci<mode><cksum><CR><LF> 
> I had a similar problem a while ago.
> I wrote a simple python hack to compute the checksum.  The manual probably 
> has an example you can test it on.
> It's also worth checking gpsd.  It knows how to talk to lots and lots of GPS 
> units and can smash some of them into a useful state.

Thanks for the suggestions.  I'll play around in Perl to get something 
going and then translate it to C for use as a start-up routine.  (I was 
going to put on of the GT+s in a Nixie clock, so Perl is out of the 
question there ;-))

The GT+s are definitely behaving strangely; I just connected the one 
that finally decided to talk to me to the computer that will be the time 
server and fired up gpsd:

# gpsd -D 4 -n -N /dev/cua00
gpsd: launching (Version 2.34)
gpsd: listening on port 2947
gpsd: running with effective group ID 0
gpsd: running with effective user ID 0
gpsd: opening GPS data source at '/dev/cua00'
gpsd: speed 9600, 8N1
gpsd: garmin_gps not active.
gpsd: no probe matched...
gpsd: gpsd_activate(1): opened GPS (6)

Didn't recognise it, just sat there.  (The documentation mentions 
specifically that it knows about GT+s.)  I re-connected the module to 
the machine with VisualGPS, now I can't get it to talk to me again. 
This doesn't seem right - either the thing should work or not.  I do 
have my suspicions about those on-board batteries and wonder if I would 
be better off without them.

Think I'll use the VP for the time server and leave the GT+s for further 
experimentation unless anyone just happens to know why they aren't 
playing along.



Matthew Smith
Smiffytech - Technology Consulting & Web Application Development
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