Connecting to a u-blox7 USB GPS sensor

Question

I am trying to connect to a U-Blox7 USB GPS sensor, following the steps outlined here. The device is detected, but not receiving GPS data. I am not not in a shielded area.

Checking that the device is detected:

$ ls /dev/tty*
/dev/tty    /dev/tty16  /dev/tty24  /dev/tty32  /dev/tty40  /dev/tty49  /dev/tty57  /dev/tty8
/dev/tty0   /dev/tty17  /dev/tty25  /dev/tty33  /dev/tty41  /dev/tty5   /dev/tty58  /dev/tty9
/dev/tty1   /dev/tty18  /dev/tty26  /dev/tty34  /dev/tty42  /dev/tty50  /dev/tty59  /dev/ttyAMA0
/dev/tty10  /dev/tty19  /dev/tty27  /dev/tty35  /dev/tty43  /dev/tty51  /dev/tty6   /dev/ttyprintk
/dev/tty11  /dev/tty2   /dev/tty28  /dev/tty36  /dev/tty44  /dev/tty52  /dev/tty60  /dev/ttyUSB0
/dev/tty12  /dev/tty20  /dev/tty29  /dev/tty37  /dev/tty45  /dev/tty53  /dev/tty61
/dev/tty13  /dev/tty21  /dev/tty3   /dev/tty38  /dev/tty46  /dev/tty54  /dev/tty62
/dev/tty14  /dev/tty22  /dev/tty30  /dev/tty39  /dev/tty47  /dev/tty55  /dev/tty63
/dev/tty15  /dev/tty23  /dev/tty31  /dev/tty4   /dev/tty48  /dev/tty56  /dev/tty7

I can see the /dev/ttyACM0 folder.

Verify if the GPS has been bound to this folder.

$ sudo cat /dev/ttyACM0
$GPTXT,01,01,02,u-blox ag - www.u-blox.com*50
$GPTXT,01,01,02,HW  UBX-G70xx   00070000 FF7FFFFFo*69
$GPTXT,01,01,02,ROM CORE 1.00 (59842) Jun 27 2012 17:43:52*59
$GPTXT,01,01,02,PROTVER 14.00*1E
$GPTXT,01,01,02,ANTSUPERV=AC SD PDoS SR*20
$GPTXT,01,01,02,ANTSTATUS=OK*3B
$GPTXT,01,01,02,LLC FFFFFFFF-FFFFFFFF-FFFFFFFF-FFFFFFFF-FFFFFFFD*2C
$GPTXT,01,01,01,NMEA unknown msg*58
$GPRMC,,V,,,,,,,,,,N*53
$GPVTG,,,,,,,,,N*30
$GPGGA,,,,,,0,00,99.99,,,,,,*48
$GPGSA,A,1,,,,,,,,,,,,,99.99,99.99,99.99*30
$GPGSV,1,1,02,15,,,21,17,,,21*79
$GPGLL,,,,,,V,N*64
$GPTXT,01,01,01,NMEA unknown msg*58

As can be seen, the sensor isn't getting the GPS values, $GPGGA,,,,,,0,00,99.99,,,,,,*48 (and most other fields) empty. I expect to see these values as in the screenshot below (from the link above).

Using raspberry pi model B+.

EDIT

A further check (after changing location shown the device sending some "unreadable data").

$ sudo cat /dev/ttyACM0
$GPTXT,01,01,02,u-blox ag - www.u-blox.com*50
$GPTXT,01,01,02,HW  UBX-G70xx   00070000 FF7FFFFFo*69
$GPTXT,01,01,02,ROM CORE 1.00 (59842) Jun 27 2012 17:43:52*59
$GPTXT,01,01,02,PROTVER 14.00*1E
$GPTXT,01,01,02,ANTSUPERV=AC SD PDoS SR*20
$GPTXT,01,01,02,ANTSTATUS=OK*3B
$GPTXT,01,01,02,LLC FFFFFFFF-FFFFFFFF-FFFFFFFF-FFFFFFFF-FFFFFFFD*2C
=&
  #4�����
         x;�|E�
               ~B}i%�b��'''''''寵b ��;%���Z��b4��A��\��$�s{U��fF'��
#4�����
       x;�|E�
             ~B}S�b=
                    #4�����
                           x;�|E�
                                 ~B}>ɵb=
                                        #4�����
                                               x;�|E�
                                                     ~B})��b=
                                                             $4�����
                                                                    x;�|E�
                                                                          ~�b=
                                                                              $4�����
                                                                                     x;�|E�
                                                                                           ~B}9�b^C

yes, but I noticed the device light isn't blicking, even as I replace it several times. — arilwan, Jan 12 '22 at 11:37
@CoderMike I have changed location, but the output received is just unreadable, (see question edit). — arilwan, Jan 12 '22 at 11:59
This seems to be running a wrong protocol. Maybe you need to configure the sensor first? — PMF, Jan 12 '22 at 12:26
This might help: https://raspberrypi.stackexchange.com/questions/113544/rpi-neo-6m-neo-8m-gps-module-setup-fix-update-problems/113601#113601 — tlfong01, Jan 12 '22 at 12:36

score 2 · Answer 1 · answered Jan 12 '22 at 12:30

2

Looks like a baudrate change, or a switchover to a binary protocol. Connect to the GPS using U-center and check how it is configured.

answered Jan 12 '22 at 12:30

Dmitry Grigoryev

27,928
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score 2 · Accepted Answer · edited Oct 24 '22 at 12:05

I can confirm the sensor is now setup correctly.

Steps:

Update sources

$ sudo apt-get update

Install the gps daemon, libraries and NTP

$ sudo apt-get install gpsd gpsd-clients ntp

Modify /etc/default/gpsd file (NTP won't work without the -n)

$ sudo cat /dev/ttyACM0
#add following lines to the /etc/default/gpsd file
DEVICES="/dev/ttyACM0"
GPSD_OPTIONS="-n"

Edit the ntp configuration file

$ sudo vi /etc/ntp.conf
# Add these lines to ntp.conf:
# gps
server 127.127.28.0 minpoll 4 maxpoll 4 prefer
fudge 127.127.28.0 time1 0.000 refid GPS stratum 15

Save/reboot
Once that's all done you should be able to type:

$ cgps -s

Output:

Checking with python:

import gpsd
gpsd.connect()
packet = gpsd.get_current()
print(packet.position())
(11.9772487, 8.4266957)

Connecting to a u-blox7 USB GPS sensor

2 Answers2