Time synchronization

This tutorial describes, how to set up the time synchronization of the system clock by disciplining the kernel of the RPi with the Ublox's PPS (Pulse-Per-Second) signal using chronyd.

Install the pps kernel driver module

Edit the /boot/config.txt and add the following line:

dtoverlay=pps-gpio,gpiopin=18

This will activate the kernel pps driver module at startup listening to GPIO pin 18 to which the timepulse output of the uBlox is connected on the MuonPi HAT board. After a restart, one should see the activated driver in the kernel module list.

lsmod showing the loaded pps_gpio kernel module

To test the pps functionality, the command-line-tool ppstest may be used (install with sudo apt install pps-tools.