The entire desire to do this came about from reading about building a Stratum 1 clock using a Raspberry PI at http://www.satsignal.eu/ntp/Raspberry-Pi-NTP.html and from the use of a Sony radio clock to provide WWVB pulses from the WWVB receiver module that was used in the radio clock.

However, all of the projects and examples I found used Linux which I did not really want to use. I much preferred to use NetBSD, but it lacked a number of critical features that would be required to make a properly working Stratum 1 clock. Interrupt support for the GPIO pins was needed and adding a PPSAPI driver that could be triggered by a GPIO interrupt would be necessary.