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moby: gps: document some findings

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Colin 2023-10-07 04:25:44 +00:00
parent 56838a4867
commit 2097c3ad77
2 changed files with 13 additions and 6 deletions
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17
hosts/by-name/moby/gps.nix
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@ -7,15 +7,16 @@
# - `screen /dev/ttyUSB2 115200`
# - `AT+QGPSCFG="nmeasrc",1`
# - `AT+QGPS=1`
# this process is automated by my `eg25-control` program and services (`eg25-control-powered`, `eg25-control-gps`)
# - see the `modules/` directory further up this repository.
#
# now, something like `gpsd` can directly read from /dev/ttyUSB1.
# now, something like `gpsd` can directly read from /dev/ttyUSB1,
# or geoclue can query the GPS directly through modem-manager
#
# initial GPS fix can take 15+ minutes.
# meanwhile, services like eg25-manager can speed this up by uploading assisted GPS data to the modem.
# meanwhile, services like eg25-manager or eg25-control-freshen-agps can speed this up by uploading assisted GPS data to the modem.
#
# geoclue somehow fits in here as a geospatial provider that leverages GPS and also other sources like radio towers
#
# support:
# support/help:
# - geoclue, gnome-maps
# - irc: #gnome-maps on irc.gimp.org
# - Matrix: #gnome-maps:gnome.org (unclear if bridged to IRC)
@ -28,6 +29,12 @@
# - puremaps?
# - osmin?
#
# known/outstanding bugs:
# - `systemctl start eg25-control-gps` can the hang the whole system (2023/10/06)
# - i think it's actually `eg25-control-powered` which does this (started by the gps)
# - best guess is modem draws so much power at launch that other parts of the system see undervoltage
# - workaround is to hard power-cycle the system. the modem may not bring up after reboot: leave unpowered for 60s and boot again.
#
# future work:
# - integrate with [wigle](https://www.wigle.net/) for offline equivalent to Mozilla Location Services

2
pkgs/additional/eg25-control/eg25-control
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@ -2,7 +2,7 @@
#!nix-shell -i python3 -p "python3.withPackages (ps: [ ])" -p curl -p modemmanager
# this script should run after ModemManager.service is started.
# typical invocation is `eg25_gps_init.py --enable-power --enable-gps`.
# typical invocation is `eg25-control --power-on --enable-gps`.
# after running, the user may `cat /dev/ttyUSB1` to view NMEA-encoded GPS information.
# the script attempts to be idempotent, such that it may be run multiple times per boot.
#