stty -F /dev/ttyAMA5 9600 cs8 -cstopb -parenb Now cat /dev/ttyAMA5 showed garbage. Good—data was flowing.
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:
The garbage was not NMEA sentences (which start with $GP or $GN ). It was random binary noise. Marta grabbed an oscilloscope: the UG-353’s TX was 3.3V, but the CM4’s RX was configured for 1.8V logic due to a broken device tree overlay. She fixed the config.txt :
dtoverlay=uart5,uart5_rx_pullup=on
The Silent NMEA Sentence
Ug-353 Gps Driver Today
stty -F /dev/ttyAMA5 9600 cs8 -cstopb -parenb Now cat /dev/ttyAMA5 showed garbage. Good—data was flowing.
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:
The garbage was not NMEA sentences (which start with $GP or $GN ). It was random binary noise. Marta grabbed an oscilloscope: the UG-353’s TX was 3.3V, but the CM4’s RX was configured for 1.8V logic due to a broken device tree overlay. She fixed the config.txt :
dtoverlay=uart5,uart5_rx_pullup=on
The Silent NMEA Sentence
