Month: December 2019

This also works on Pi 3.

• Hardware: A GPS with serial connected to the Pi’s serial port, and PPS connected to gpio 18 (physical pin 12 on the GPIO connector)
• If possible, configure GPS to output GPZDA at 9600 baud. GPSD will find other baud rates, but takes approximately 8 minutes to get to 115200, and 9600 is the first one it tries.

sudo raspi-config, disable serial console login, enable hardware serial port
sudo apt install pps-tools gpsd gpsd-clients python-gps chrony
edit /etc/modules, add:

pps-gpio

edit /boot/firmware/config.txt (or /boot/config.txt), add:

dtoverlay=pps-gpio,gpiopin=18

edit /etc/default/gpsd, set device to “/dev/ttyS0”, options to “-n -b”
sudo systemctl enable gpsd

edit /etc/chrony/chrony.conf, comment out all servers and pools, add:

refclock SHM 0 poll 0 refid GPS precision 1e-1 offset 0.055
refclock PPS /dev/pps0 lock GPS poll 0 refid PPS precision 1e-9

sudo systemctl restart chrony

Monitor using chronyc sources, or chronyc sourcestats

Begin by downloading an image courtesy of James Chambers

Use etcher to write the image to an SD card

Next follow the instructions on the ROS wiki. Make sure to install the “bare bones” version if you are running a headless Pi.

That’s it! Thanks to the James Chambers image this ended up being pretty easy!