03 - RouteTrack Pi — gpsd Installation & GPS Validation

Date: December 24th, 2025 Category: Raspberry Pi / GPS / Linux Services Backlink: RouteTrack Pi — Connecting GPS Hardware 

 

 

 Goal 

 This page covers: 

 

 

 Installing gpsd and GPS tools (Global Positioning Satellite Daemon Tools) 

 

 

 Confirming the USB GPS receiver is outputting raw NMEA sentences 

 

 

 Creating a stable /dev/gps0 device symlink via udev rules 

 

 

 Running gpsd reliably as a standalone systemd service 

 

 

 Validating that GPS data is readable through gpspipe 

 

 I had to use a stand alone service because gpsd wouldn't work out of the box with my GPS Reciever. 

 This is a workaround for that on this page. 

 Some GPS units will work without bypassing TTP and using a seperate standalone systemd service. 

 This page is specific to the GPS I used that needed a workaround. 

 

 Device: GlobalSat BU‑353N USB GPS Receiver 

 

 Install gpsd + tools 

 Run: 

 sudo apt update

sudo apt install -y gpsd gpsd-clients 

 This installs: 

 

 

 gpsd (daemon) 

 

 

 gpspipe , cgps (client tools) 

 

 

 

 Confirm the GPS receiver is detected 

 Plug in the USB GPS receiver, then verify the device appears: 

 ls -l /dev/ttyUSB* 

 example: 

 

 Linux sees the GPS receiver. 

 

 Validate raw NMEA output from the GPS 

 Before involving gpsd, verify the GPS is actually transmitting: 

 sudo stty -F /dev/ttyUSB0 4800 cs8 -cstopb -parenb -ixon -ixoff -crtscts -echo

sudo timeout 8 cat /dev/ttyUSB0 | head -n 20 

 Expected output should look like: 

 $GPGGA,...

$GPGSA,...

$GPRMC,...

 

 If you see NMEA sentences, the receiver is working at  4800 baud . 

 

 Create a stable GPS symlink  /dev/gps0 (udev rule) 

 The GPS device may sometimes appear as a different tty device, so we create a stable symlink called /dev/gps0 . 

 Create the udev rule 

 sudo nano /etc/udev/rules.d/10-gps-pl2303.rules 

 Paste: 

 SUBSYSTEM=="tty", ATTRS{idVendor}=="067b", ATTRS{idProduct}=="23a3", SYMLINK+="gps0" 

 These id's come from udev's info: 

 

 

 idVendor=067b 

 

 

 idProduct=23a3 

 

 

 Reload udev and trigger: 

 sudo udevadm control --reload-rules

sudo udevadm trigger

sudo udevadm settle 

 Verify: 

 ls -l /dev/gps0 

 Expected: 

 

 

 Disable gpsd.socket and build a standalone gpsd service 

 Socket activation can cause inconsistent behavior during testing, so this project uses a dedicated standalone systemd service. 

 Disable/mask the socket unit 

 sudo systemctl disable --now gpsd.socket

sudo systemctl mask gpsd.socket 

 

 Create  gpsd-standalone.service 

 Create the service: 

 sudo nano /etc/systemd/system/gpsd-standalone.service 

 This is the code for setting up the new service: 

 [Unit]

Description=GPSD Standalone (RouteTrack)

After=network.target

Wants=network.target

[Service]

Type=simple

User=gpsd

Group=dialout

ExecStart=/usr/sbin/gpsd -N -n -b -s 4800 -S 2947 /dev/gps0

Restart=on-failure

RestartSec=2

[Install]

WantedBy=multi-user.target

 

 Important Notes 

 

 

 -s 4800 forces correct baud rate 

 

 

 -S 2947 binds gpsd to port 2947 (localhost) 

 

 

 We intentionally do not use -F /run/gpsd.sock because it caused permission errors for the gpsd user under systemd. 

 

 

 This service uses /dev/gps0 so the device name stays consistent. 

 

 

 Enable + start: 

 sudo systemctl daemon-reload

sudo systemctl enable --now gpsd-standalone.service 

 Check status: 

 systemctl status gpsd-standalone.service --no-pager -l 

 Notice it is enabled, active and running the line from the ExecStart: 

 

 

 Confirm gpsd is listening on port 2947 

 Run: 

 ss -ltnp | grep 2947 

 It is listening on ipv4 and ipv6 ports: 

 

 

 Validate GPS data through gpsd (JSON output) 

 Run: 

 gpspipe -w -n 25 

 ✅ Expected: 

 

 

 TPV messages 

 

 

 SKY messages 

 

 

 mode: 3 when a fix is established 

 

 

 latitude/longitude values updating 

 

 

 Example indicators showing some GPS coordinates: 

 

 

 Verifying Satellites and that everything is working: use: 

 cgps 

 

 Next Steps 

 The GPS subsystem is now stable, validated, and running as a dedicated systemd service. Upcoming work will build on this foundation: 

 

 

 Integrate gpsd with RouteTrack 

 

 

 Consume GPS data via localhost port 2947 

 

 

 Parse TPV updates for real-time position tracking 

 

 

 

 

 Add health checks 

 

 

 Monitor gpsd service status 

 

 

 Alert if GPS fix drops below mode: 3 

 

 

 

 

 Visualization 

 

 

 Map GPS coordinates to a live or logged route view 

 

 

 Export NMEA or JSON logs for later analysis