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Time (atomic) — NTP-synchronized time with offline-resilience

SUPERSEDED by connections/time-atomic/ (Wave 3 #55, shipped 2026-08-02).

What it does

RoamCore includes notes for keeping HA's clock accurate even when offline (in a van with intermittent connectivity). The recipe recycles the upstream HA core time integration (since 2022.x — exposes NTP servers + sensor.time + sensor.date + date/time helpers) + a thin RoamCore automation wrapper that runs the THREE §7 automations (NTP cadence refresh on boot + GPS time correction on device_tracker + timezone change + RTC fallback when NTP unreachable for N minutes).

Why it's useful in a van

  • The van can lose LTE / Starlink for hours — the recipe's Path C RTC fallback (DS3231 / RV-3028 I2C RTC module on the van's NUC / SBC + the SBC's systemd-timesyncd fallback config) keeps accurate time even when offline
  • GPS satellites carry atomic-clock-grade time signals — the recipe's Path B GPS time correction (Traccar Wave 3 #36 / HA Companion app / Wican Pro Wave 3 #6 OBD-II's GPS feed) uses GPS time when NTP is unreachable but GPS is
  • NTP is the canonical time-sync mechanism when the WAN is reachable — the recipe's Path A NTP uses HA core's time integration with the recommended NTP server list (time.cloudflare.com + time.google.com + pool.ntp.org)

How to install

  • Optional: DS3231 / RV-3028 I2C RTC module for Path C RTC fallback (otherwise the recipe relies on Path A NTP + Path B GPS only)
  • Optional: Traccar Wave 3 #36 server OR HA Companion app OR Wican Pro Wave 3 #6 OBD-II reader for Path B GPS time correction (otherwise the recipe relies on Path A NTP + Path C RTC only)

  • No extra hardware required for Path A NTP (just HA core's time integration + the WAN backhaul)

  • See: connections/time-atomic/docs/recipe.md

  • RoamCore time helpers package: homeassistant/packages/roamcore_weather_time.yaml
  • HA core time integration: https://www.home-assistant.io/integrations/time/
  • Cross-reference to Wave 3 #54 timezone-geolocator (the time-category complement — handles "what timezone IS it?"; this slice handles "what time IS it?"): connections/timezone-geolocator/
  • Cross-reference to Traccar Wave 3 #36 (the canonical GPS source for Path B GPS time correction): connections/traccar/
  • Cross-reference to Wican Pro Wave 3 #6 (the optional OBD-II GPS source for Path B GPS time correction): connections/wican-pro/

How it works

What RoamCore does behind the scenes.