| | 1 | * Time |
| | 2 | This document was created by Steven Baltakatei Sandoval on |
| | 3 | ~2020-07-23T22:27Z~ under a [[https://creativecommons.org/licenses/by-sa/4.0/][Creative Commons BY-SA 4.0 license]]. It |
| | 4 | was updated by Steven Baltakatei Sandoval on ~2020-07-25T19:34Z~ |
| | 5 | ** Development Task list |
| | 6 | *** Set up prototype unit |
| | 7 | **** Solder wire for PPS signal |
| | 8 | **** Follow guide |
| | 9 | - [[https://ozzmaker.com/forums/topic/connecting-gps-pps-pin/][Ozzmaker post]] on ~PPS~ wiring and a [[https://www.satsignal.eu/ntp/Raspberry-Pi-NTP.html][guide]] recommendation. |
| | 10 | - [[http://www.satsignal.eu/raspberry-pi/Schmidt-RPZ-NTP-2016.pdf][Schmidt article]] on Raspberry Pi Zero time server. |
| | 11 | - [[https://gpsd.gitlab.io/gpsd/gpsd-time-service-howto.html][GPSD dev ref]] page for ~gpsd~ interfacing with ~ntp~. |
| | 12 | *** Document prototype unit |
| | 13 | ** Narrative |
| | 14 | The ~ninfacyzga-01~ device is equipped with an Ozzmaker BerryGPS-IMU |
| | 15 | module which provides time and location data to ~gpsd~. The time is |
| | 16 | provided by GPS satellites which themselves are [[https://science.nasa.gov/science-news/science-at-nasa/2002/08apr_atomicclock/][equipped]] with atomic |
| | 17 | clocks. This extremely accurate set of clocks are needed since a GPS |
| | 18 | receiver calculates its position in space using a General Relativity |
| | 19 | calculation that uses the small variations in the time stamps received |
| | 20 | from each satellite. This means that ~gpsd~ may be used to set the |
| | 21 | system clock without a need for an internet connection to a default |
| | 22 | Debian time server; ~ninfacyzga-01~ can be its own time server. |
| | 23 | ** Description |
| | 24 | *** Hardware |
| | 25 | Ozzmaker BerryGPS-IMU, Version 3 |
| | 26 | *** Software |
| | 27 | This guide describes steps that may be used to convert a Raspberry Pi |
| | 28 | into a time server using ~gpsd~. |
| | 29 | ** Operating Procedures |
| | 30 | *** Initial Startup |
| | 31 | **** Install Raspbian 10 (Buster) onto a Raspberry Pi Zero W. |
| | 32 | **** Install Hardware |
| | 33 | See [[https://ozzmaker.com/forums/topic/connecting-gps-pps-pin/][this]] Ozzmaker forum topic about connecting the BerryGPS-IMU |
| | 34 | ~T_PULSE~ pin to GPIO 18. |
| | 35 | |
| | 36 | Connect the ~T_PULSE~ connection on the BerryGPS-IMU-3 to GPIO pin 18 |
| | 37 | in order to enable ~gpsd~ to read the PPS signal for forwarding to |
| | 38 | ~ntp~. |
| | 39 | |
| | 40 | **** Install Software |
| | 41 | Run the following command to install the required packages. |
| | 42 | : $ sudo apt install usbmount eject gpsd gpsd-clients python-gps pps-tools ntp |
| | 43 | |
| | 44 | These instructions assume that ~gpsd~ has already been setup to |
| | 45 | provide NMEA sentences to ~gpspipe~ for location. See the ~README.org~ |
| | 46 | in ~doc/location~ for details. Basically, ~gpsd~ needs to be told via |
| | 47 | its ~/etc/default/gpsd~ configuration file of which ~/dev/tty???~ will |
| | 48 | provide the raw GPS module data. |
| | 49 | |
| | 50 | *** Normal Startup |
| | 51 | *** Normal Operation |
| | 52 | *** Normal Shutdown |
| | 53 | *** Unscheduled Shutdown |
| | 54 | |
| | 55 | |
projects / EVA-2020-02.git / blame_incremental