andrew.mileski@gmail.com said: > Beware that USB-to-Serial converters are pretty horrible for precise timing > applications, like PPS on the CD pin. It can be done on a GPIO pin instead, > but requires some hacking and re-compiling. What sort of hacking or re-compiling do you have in mind? I didn't have any troubles getting PPS via GPIO. It's a bit of editing on run-time config files. From my notes: in /boot/config.txt add new line: dtoverlay=pps-gpio,gpiopin=4 (The pin number depends on the GPS HAT.) In /etc/modules add new line: pps-gpio -- These are my opinions. I hate spam.