The UG-353 was wired to UART5 on a Raspberry Pi Compute Module 4. Marta had written a simple systemd service to start gpsd with the correct options:
Now $GPGGA sentences appeared cleanly.
The Silent NMEA Sentence
Marta checked the datasheet. UG-353 defaults to 9600 baud , but the Linux kernel expected 115200 for the UART. She fixed the stty settings:
dtoverlay=uart5,uart5_rx_pullup=on
stty -F /dev/ttyAMA5 9600 cs8 -cstopb -parenb Now cat /dev/ttyAMA5 showed garbage. Good—data was flowing.
Marta was a firmware engineer for a small agricultural robotics startup. Her team had just switched from an old U-Blox GPS to the UG-353 (a common, low-cost 10Hz GPS module with a UART interface). The robot’s navigation stack was failing. “No fix,” the logs said. “No fix.” ug-353 gps driver
sudo gpsd /dev/ttyAMA5 -F /var/run/gpsd.sock But cgps showed a blank screen. Zero satellites. Sky was clear.