stratum one on pi 4?
Hal Murray
hmurray at megapathdsl.net
Sat Sep 21 01:09:31 UTC 2019
Are you trying to get the PPS via a serial port or via GPIO?
The serial ports on many SoC chips like the Pi only support read+write data,
no modem control signals. There are pins assigned for the modem control, but
they are shared with other uses and most TTY hacking doesn't use them so they
get used for other purposes.
The Pi-3 has ttyAMA0 used internally for BlueTooth.
My notes from setting up a Pi - they are mostly reminders. I/you may have to
poke around to figure out what each step is actually doing and/or why.
--------
# PPS via gpio
# http://www.satsignal.eu/ntp/Raspberry-Pi-NTP.html#easy
vi /boot/cmdline.txt
remove the chunk(s) with ttyAMA0
vi /boot/config.txt
add new line: dtoverlay=pps-gpio,gpiopin=18
pin 4 on Adafruit GPS HAT
vi /etc/modules
add new line: pps-gpio
vi /etc/inittab
run raspi-config Interfacing-Options/Serial
comment out getty line for ttyAMA0 (at bottom)
# Pi-3 uses ttyAMA0 for BlueTooth
systemctl disable hciuart
Add "dtoverlay=pi3-disable-bt" to /boot/config.txt
# https://frillip.com/raspberry-pi-3-uart-baud-rate-workaround/
# https://www.raspberrypi.org/forums/viewtopic.php?f=107&t=138223
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