Description
To enable the GPS as a pps source. Do the following.
add "dtoverlay=pps-gpio,gpiopin=25" to a new line in /boot/config.txt
add "pps-gpio" to a new line in /etc/modules
install pps tools:
sudo apt-get install pps-tools
reboot
run ppstest /dev/pps0
your output should look like this:
$ sudo ppstest /dev/pps0
trying PPS source "/dev/pps0"
found PPS source "/dev/pps0"
ok, found 1 source(s), now start fetching data...
source 0 - assert 1427275430.004698032, sequence: 613 - clear 0.000000000, sequence: 0
source 0 - assert 1427275431.004698969, sequence: 614 - clear 0.000000000, sequence: 0
source 0 - assert 1427275432.004700114, sequence: 615 - clear 0.000000000, sequence: 0
source 0 - assert 1427275433.004703447, sequence: 616 - clear 0.000000000, sequence: 0
source 0 - assert 1427275434.004705218, sequence: 617 - clear 0.000000000, sequence: 0
source 0 - assert 1427275435.004708186, sequence: 618 - clear 0.000000000, sequence: 0
source 0 - assert 1427275436.004709644, sequence: 619 - clear 0.000000000, sequence: 0
^C