The core contribution of this repository is a FreeBSD kernel module that enables a GPIO input to handle a Pulse-Per-Second timing signal from a GPS unit to create a Stratum-1 NTP Server.
The software has been tested on a Raspberry PI-2 using an Adafruit Ultimate GPS Breakout (version 3) and also with the the AdaFruit Ultimate GPS Hat. The "Hat" provides a nicer footprint, but requires changes in the FreeBSD boot environment to work.
This repository contains a FreeBSD driver, some sample patch files, and documentation in the Wiki Pages.
The driver was built and tested using:
- FreeBSD 11.0,
- The crochet build tool,
- A Raspberry PI-2,
- A GPS board that provides Pulse-Per-Second outputs. As noted, this driver has only been tested with the AdaFruit products mentioned above. The driver should be adaptable to any GPS hardware that provides a PPS output compatible with the PI's 3.3v GPIO input, but it is up to you to do the correct wiring.
- The
u-boot-rpiFreeBSD port (see/usr/ports/sysutils/u-boot-rpi2in the FreeBSD ports tree. - A build environment for FreeBSD and the port.
Be sure to read through all the steps in the FreeBSD-GPIO-PPS Documentation before trying to use this driver!