Difference between revisions of "GPS daemon"

Latest revision as of 19:39, 22 January 2020

About

From gpsd website: gpsd is a service daemon that monitors one or more GPSes or AIS receivers attached to a host computer through serial or USB ports, making all data on the location/course/velocity of the sensors available to be queried on TCP port 2947 of the host computer. With gpsd, multiple location-aware client applications (such as navigational and wardriving software) can share access to receivers without contention or loss of data. Also, gpsd responds to queries with a format that is substantially easier to parse than the NMEA 0183 emitted by most GPSes. The gpsd distribution includes a linkable C service library, a C++ wrapper class, and a Python module that developers of gpsd-aware applications can use to encapsulate all communication with gpsd.

Installation

$ make menuconfig

Package Selection for the target  --->
    Hardware handling / blockdevices and filesystem maintenance  --->
        [*]   gpsd
                devices/protocol support  --->
                gpsd features  --->

• Let default devices/features if you don't know what they mean.

$ make

• reflash your rootfs

Usage

• gpsd is automatically launched at startup by /etc/init.d/S50gpsd.

• On APF27 + Wireless extension, at first startup you may need to add the following line in the start() method of this script:

# nano /etc/init.d/S50gpsd


start() {
        stty -F /dev/ttySMX4 raw -echo -echoe -echok 38400               <<<<<<<<<<<<--------------
        echo -n "Starting $NAME: "
        start-stop-daemon -S -q -p $PIDFILE --exec $DAEMON -- -P $PIDFILE $DEVICES && echo "OK" || echo "Failed"
}

Manual access

• gpsd is a daemon running in background and waiting for client to connect to its TCP port 2947. To check it is well running, you can connect to it with telnet:

# telnet localhost 2947

• then you can give it some commands (more infos here):

?VERSION;
{"class":"VERSION","release":"2.94","rev":"2010-06-09T13:27:04","proto_major":3,"proto_minor":2}

?DEVICES;
{"class":"DEVICES","devices":[{"class":"DEVICE","path":"/dev/ttySMX4","activated":1276183248.47,"flags":1,"driver":"Generic NMEA","native":0,"bps":0,"parity":"N","stopbits":1,"cycle":1.00}]}

?POLL;
{"class":"POLL","timestamp":1276183453.266,"active":1,"fixes":[{"class":"TPV","tag":"GLL","device":"/dev/ttySMX4","time":1276176096.000,"ept":0.005,"lat":47.239685500,"lon":6.019204667,"alt":268.100,...

Graphical clients

• cgps (ncurses based), installed by default:

# cgps -s -u m
┌───────────────────────────────────────────┐┌─────────────────────────────────┐
│    Time:       2019-06-10T13:41:26.0Z     ││PRN:   Elev:  Azim:  SNR:  Used: │
│    Latitude:    47.238710 N               ││   8    07    079    00      N   │
│    Longitude:    6.018278 E               ││   9    47    282    29      Y   │
│    Altitude:   1055.4 m                   ││  12    10    216    00      N   │
│    Speed:      0.7 km/h                   ││  15    79    194    39      Y   │
│    Heading:    265.5 deg (true)           ││  17    00    000    22      N   │
│    Climb:      0.0 m /min                 ││  18    00    000    22      N   │
│    Status:     3D FIX (43 secs)           ││  26    84    265    25      Y   │
│    GPS Type:   Generic NMEA               ││  27    61    291    33      Y   │
│    Horizontal Err:  +/- 83 m              ││                                 │
│    Vertical Err:    +/- 75 m              ││                                 │
│    Course Err:      n/a                   ││                                 │
│    Speed Err:       +/- 114 km/h          ││                                 │
│                                           ││                                 │
│                                           ││                                 │
│                                           ││                                 │
│                                           ││                                 │
│                                           ││                                 │
│                                           ││                                 │
└───────────────────────────────────────────┘└─────────────────────────────────┘

• Navit, etc....

Remote usage

• As gpsd can be used remotely, it can run on your SOM and you can launch graphical tool on your PC to visualize your datas like xgps (in order, IP adress of your gpsd/SOM, gpsd port, serial interface name):

$ xgps 192.168.0.31:2947:/dev/ttyAPP0

• or foxtrotgps: https://www.foxtrotgps.org/ (gpsd/your SOM IP address has to be configured in tool preferences GUI)

Links

• gpsd website