Force system time from gpsd on radxa zero with Armbian

gpsd_time_radxa_zero.md

• Install Armbian (and disable any undesired homekit, containerd stuff)
• Setup /dev/ttyAML1 UART. Edit /boot/armbianEnv.txt and add the line:

overlays=uart-ao-b-on-gpioao-8-gpioao-9

This assumes the prefix line:

overlay_prefix=meson-g12a-radxa-zero

• Install gpsd and gpsd-clients
• Edit gpsd config:

DEVICES="/dev/ttyAML1"

# Other options you want to pass to gpsd
GPSD_OPTIONS="-n -r -b -D2 -s 38400"

• Ensure gpsd is in dialout group: sudo adduser gpsd dialout

• Allow /dev/ttyAML1 in apparmor. Edit /etc/apparmor.d/usr.sbin.gpsd to ensure the desired device is present, eg: /dev/tty{,S,USB,AML,AMA,ACM}[0-9]* rw,

• Install chrony sudo apt-get install chrony

• Edit /etc/chrony/chrony.conf and at the end add:

allow

refclock SHM 0 refid GPS precision 1e-1 offset 0.9999 delay 0.2

• Disable network time sources by commenting out lines in chrony.conf file with pool and DHCP