How the System Fits Together

How the System Fits Together

Three parts make up the system: two websites and the device in the aircraft. Each connection between them is described below, so you know what the device needs from each part and what still works when it is offline.

  pyefis.aerocommons.org            navdata.aerocommons.org
  (configurator)                    (navdata service)
  panel design, aircraft numbers    signed data packs
          |                                  |
          | pyefis-data config-pull          | pyefis-data update
          | (paired device, at boot)         | (daily timer, or on demand)
          v                                  v
  +--------------------------- the device ----------------------------+
  |  ~/makerplane/pyefis/config   ~/makerplane-data/<kind>/current    |
  |               \                  /                                |
  |                 pyEFIS (screens)  <--- NetFIX, port 3490 ---      |
  |                                                            \      |
  |                                     FIX-Gateway (FIX database)    |
  |                                     sensors, CAN-FIX, GPS, sim    |
  +--------------------------------------------------------------------+

The device: FIX-Gateway and pyEFIS

FIX-Gateway holds the FIX database: a set of named values ("FIX keys") such as IAS, ALT, PITCH, TACH1 and COURSE. Its plugins fill the database from whatever the aircraft has (CAN-FIX, serial GPS and navigators, engine monitors, X-Plane or FlightGear on the bench). Some plugins compute values instead: compute derives values and selects the navigation source, and flightplan sequences the active flight plan and produces the course and deviation the HSI shows. See the fix-gateway wiki for each plugin.

pyEFIS draws the screens. It connects to FIX-Gateway over NetFIX, by default at 127.0.0.1:3490 (FixServer and FixPort in config/main/default.yaml). It reads the keys its instruments need, and writes back the few that the pilot sets from the panel, such as the altimeter setting (BARO) and the heading bug (HEADBUG). Every key carries quality flags, and the instruments show them: a failed key reads X or XXX in place of digits. See Customizing Beyond the Configurator.

A fresh FIX-Gateway install has its demo plugin enabled (DEMO: true in its config/preferences.yaml), so the instruments come alive with simulated values before any hardware is connected.

The configurator: your panel

You design the panel on pyefis.aerocommons.org and pair the device to it once. After that, pyefis-data config-pull fetches the device's latest panel and installs it under ~/makerplane/pyefis/config. The shipped screen files are not modified. The pull keeps a backup and rolls back automatically if pyEFIS fails to start on the new panel.

The pull runs once at boot, and whenever you run it by hand. Nothing pulls a panel in flight, and a device with no network keeps the panel it has.

The configurator also holds your aircraft's numbers: V-speeds, gauge ranges and warning bands, fuel tanks. These live in FIX-Gateway, not in the panel, because every instrument reads them from the FIX database. Today you download them as aircraft.ini and install it in FIX-Gateway by hand; only the altimeter setting units travel with config-pull. See Designing Your Panel.

The navdata service: your data

navdata.aerocommons.org publishes the data the map, the flight plan, synthetic vision and the HSI draw on. Every pack is listed in a signed catalog with its SHA-256. The pyefis-data updater checks the catalog's signature before trusting it and each pack's hash before installing it, then switches it into place atomically. A failed or tampered download never replaces good data.

Packs install under ~/makerplane-data/<kind>/. By default the updater tracks the core navigation kinds (navdata, navaids, obstacles, cifp, procedures). Bulk packs such as terrain, water and roads are opt-in by region, chosen on the device's Data Status screen or in ~/.makerplane/pyefis/data.yaml. A daily systemd timer runs the update; a USB stick can carry packs to a hangar without a network.

pyEFIS reads the updater's status file, ~/.makerplane/pyefis/status.json, to show data currency on the Data Status screen and to annunciate out-of-date data.

See the makerplane-data wiki for how packs are built and verified and the overall architecture.

What works offline

Part	Needs a network?
Flying: FIX-Gateway and pyEFIS	No. Everything runs on the device.
Changing the panel	Only to pull it. The installed panel stays until the next successful pull.
Updating data	Network or a USB stick. Installed packs stay in use until replaced.