Project 1: GPS-based NTP server

Source: Microsecond accurate NTP with a Raspberry Pi and PPS GPS

Info

This page describes setting up a GPS module with a Pi. The GPS module needs to have a 3-5V input, with serial AND PPS outputs (5 pins minimum). Example: Adafruit Ultimate GPS Breakout.

Setup:

1. Install packages:

   sudo apt install pps-tools gpsd gpsd-clients gpsd-tools chrony
   

2. Add these lines to the end of /boot/config.txt

   # the next 3 lines are for GPS PPS signals
   dtoverlay=pps-gpio,gpiopin=18
   enable_uart=1
   init_uart_baud=9600
   

3. Add this text to the end of /etc/modules:

   pps-gpio
   

These programs and config changes enable PPS time sync inputs on GPIO pin 18 (real Pin 12), and initializes the serial COM port with a baud rate of 9600.

Wire up the GPS module:

Pinout:

1. GPS PPS to RPi pin 12 (GPIO 18)
2. GPS VIN to RPi pin 2 or 4
3. GPS GND to RPi pin 6
4. GPS RX to RPi pin 8
5. GPS TX to RPi pin 10

Picture reference (note that all the Pi pins are seqential):

Check GPS functionality

TBD