[ntp:questions] How to debug GPS PPS?

xyz-2041 xyz2041 at gmail.com
Mon Feb 15 07:07:29 UTC 2010


On Feb 14, 4:58 pm, David Lord <sn... at lordynet.org> wrote:
> xyz-2041 wrote:
> > Thanks for your responses, guys.  Will reply in the future.
>
> > Tried Garmin software to try to talk to the unit on a
> > Windows box:
>
> >    <https://buy.garmin.com/shop/store/downloadsUpdates.jsp?
> > product=010-00124-00&cID=170&pID=70>
>
> > None of these 3 programs worked.
>
> > Tried MS Hyperterminal.  No good.
>
> > Tried RealTerm (<http://realterm.sourceforge.net/>).  Got to see
> > the messages once I got it working at 4800.  RealTerm shows
> > the dataflow just like a breakout box.  Saw that it is *not* sending
> > PPS on pin 1.  Just sending messages on pin 2.
>
> What sentences is it sending NMEA or binary?
>
> How do you have the unit wired to the serial port?
> The JST has pins 1-12 1=TxD2 2=RxD2 3=PPS 4=TxD1 5=TxD2
> 6=PD 7=AuxBat 8=GND 9/10=3.6 to 6V 11=nc 12=NMEA-out(cmos)
>
> You need to check on below, it's best I can work out
>
> ie JSTpin      D9pin
>       3 --------- 1
>       4 --------- 2
>       5 --------- 3
>       8 ---+----- 5
>            |
>            +---- 0V
>      10 -------- +3.6 to +6V
>
> CMOS generated RS232 levels should be ok but depends on
> serial port of your pc. PPS out to DCD is given as 700mVp-p
> into 50r so will need converting to rs232.
>
> > Tried to send  a message to change to 9600, and turn PPS on.
> > Ignored messages because of improper syntax.  Needs
> > proper checksum.
>
> I have a gwbasic program for working out required messages.
> GPSD will do it for you. Garmin site also have a windows
> utility for generating required commands with checksum.
>
>
>
> > Does anyone know of software that actually works with this
> > unit?
>
> GPSD?
>
> David


Changed back to the Oncore:

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# GPS Oncore driver
# server 127.127.30.0  prefer
server 127.127.30.0
fudge  127.127.30.0   refid GPSo

# PPS driver:
server 127.127.22.0   prefer
fudge  127.127.22.0   refid PPS

# Generic NMEA GPS Receiver:
# server 127.127.20.0
# fudge  127.127.20.0   time1 0.752 refid NMEA
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Pin 1 = PPS                       (Light is blinking once per second
for about 200 ms)
Pin 2 = Data: GPS -> PC    (Light blinks once per second--after pin 1--
for about 300-400 ms)
Pin 3 = Data: PC   -> GPS
Pin 5 = Ground


Installed:

 pkg_info | grep gpsd
gpsd-2.90           Daemon that monitors one or more GPSes attached to
a host c


# ls -lta /dev | grep cua
crw-rw----   1 uucp      dialer      0,  41 Feb 15 00:33 cuad0
lrwxr-xr-x   1 root      wheel            5 Feb 14 15:42 gps0 -> cuad0
lrwxr-xr-x   1 root      wheel            5 Feb 14 15:42 oncore.pps.0 -
> cuad0
lrwxr-xr-x   1 root      wheel            5 Feb 14 15:42 oncore.serial.
0 -> cuad0
lrwxr-xr-x   1 root      wheel            5 Feb 14 15:42 pps0 -> cuad0
lrwxr-xr-x   1 root      wheel            5 Feb 14 15:42 refclock-0 ->
cuad0
crw-rw----   1 uucp      dialer      0,  42 Feb 14 15:42 cuad0.init
crw-rw----   1 uucp      dialer      0,  43 Feb 14 15:42 cuad0.lock


gpsd outputs nothing at all:

# /usr/local/sbin/gpsd /dev/cuad0
#


# /usr/local/bin/gpscat -s 9600N1 /dev/cuad0

Get some HEX output once per second:

\x08'\xa2\x03\x08#\xa2\x06\x00\x00 \x08\x081\xa2\x17\x00\x00\x00\x1c
\x00\x00\x00\x08*
@@Ea\x02\x0f\x07\xda\x004+\x00\x02\xea\xb1\x08\xce,\xbf\xec>
\x0f0\x00\x00N\xb3\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01

     remote           refid      st t when poll reach   delay
offset  jitter
==============================================================================
...
 GPS_ONCORE(0)   .GPSo.           0 l    -   16    0    0.000
0.000   0.001
 PPS(0)          .PPS.            0 l    -   64    0    0.000
0.000   0.001

How can it be getting data on the serial port but NTP
can't seem to see it?








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