config.append.txt

# RPI NTP configuration.
# Delete everything after the line above to return to defaults.

# Note that 'arm_boot=1', if present, was commented out
# by the NTP installer.

# See /boot/overlays/README for documentation on these.

# CPU Timing. We force everything to 1000MHz (PI3 speeds), as
# there is no need to overclock this device. We just want a
# fixed speed, that will not be scaled up and down by power
# management
arm_freq=1000

# This is headless. Doesn't need GPU RAM
gpu_mem=16

# Disable bluetooth which uses pins 14 and 15, returning
# them for use by ttyAMA0
dtoverlay=disable-bt

# Enable PPS on GPIO Pin 18 (physical pin 12)
dtoverlay=pps-gpio,gpiopin=18

# Other options to pps-gpio are:
# dtoverlay=pps-gpio,gpiopin=18,assert_falling_edge=on,capture_clear=on

# Depending on your GPS device, you may need to set assert_falling_edge=on,
# which triggers the PPS event when the PPS line turns OFF, not when it turns
# ON. If you have a large amount of jitter on your PPS line, you may need to
# set that, and then add a fudge to your PPS line.

# capture_clear=on is mainly for debugging the above. Turning that on will
# show you TWO events in ppstest, and you can use that to figure out if
# some PPS triggers are being missed.