Note the LTE/GNSS hat is car-unit only

The hat sits in a custom enclosure on the car Orin and isn't swapped
to the development unit, so modem and gpsd testing happens on the car
unit and gnss development elsewhere runs on its mock input.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

README.md

@@ -32,10 +32,11 @@ Planned repositories and the reasoning behind the split are described in
 
 | Part | Role |
 |---|---|
-| NVIDIA Jetson Orin Nano Super (`mikkeli-orin-nano-2`) | Main compute, JetPack r36.4 / Ubuntu 22.04 |
-| PEAK PCAN-USB | Car CAN bus access (`can1`, 500 kbps) |
-| Onboard MTTCan | Second CAN interface (`can0`) |
-| Waveshare SIM7600G-H-M.2 | LTE Cat 4 + GNSS |
+| NVIDIA Jetson Orin Nano Super (`mikkeli-orin-nano`) | Car unit: main compute, JetPack r36.4 / Ubuntu 22.04 |
+| NVIDIA Jetson Orin Nano Super (`mikkeli-orin-nano-2`) | Development unit: builds, CI, bench (see [REPOS](docs/REPOS.md)) |
+| PEAK PCAN-USB | Car CAN bus access (`can_pcan`, 500 kbps) |
+| Onboard MTTCan | Second CAN interface (`can_onboard`) |
+| Waveshare SIM7600G-H-M.2 | LTE Cat 4 (povo, fallback uplink below WiFi/Ethernet) + GNSS |
 
 Details and rationale live in the environment repo's
 [bill of materials](gitea:yukart/orin-nano-env-setup).

docs/ARCHITECTURE.md

@@ -16,7 +16,7 @@ rest down.
 ## Shape
 
 ```
-   CAN (can1) ──▶ can-bridge ──┐
+   CAN         ──▶ can-bridge ──┐
    OBD-II      ──▶ obd-poller ─┤
    GNSS        ──▶ gnss        ├──▶  message bus  ──┬──▶ recorder (disk)
    camera      ──▶ vision*     ─┘                   ├──▶ hud (local video out)
@@ -84,6 +84,8 @@ Payloads: a self-describing JSON envelope for decoded signals; compact binary fo
 Every envelope carries **two clocks**. `monotonic` is authoritative for ordering
 and intervals; `timestamp` is the absolute reference and may step, since the car
 boots without network and NTP corrects the clock once LTE connects mid-drive.
+The car unit has no RTC battery, so until then the clock sits at roughly the
+last shutdown time — offset by however long the car was parked.
 
 Topic names, payload schemas and the signal registry live in
 [contracts](gitea:yukart/contracts).
@@ -259,10 +261,11 @@ They are never committed. `tool-mapmint` holds the scripts that fetch and build
 them, plus a report of each build's provenance; `svc-nav` consumes the output. The
 artifacts themselves live outside git and never touch the workstation-side repo.
 
-They reach the car by `rsync` **over the LAN only, never over LTE** — the IoT SIM
-is not a sensible transport for a multi-gigabyte tile set. Gate the sync on a
+They reach the car by `rsync` **over the LAN only, never over LTE** — the metered
+povo SIM is not a sensible transport for a multi-gigabyte tile set. Gate the sync on a
 reachable LAN target rather than on an SSID, so the check validates the thing it
-actually needs, and treat NetworkManager's metered flag as a second guard.
+actually needs, and treat NetworkManager's metered flag as a second guard (set on the `povo`
+connection).
 Cadence is quarterly or on annoyance; road geometry does not move fast enough to
 justify anything more.
 

docs/REPOS.md

@@ -153,8 +153,12 @@ Two Orin Nanos, and they have different jobs:
 
 | Unit | Role |
 |---|---|
-| Development Orin | Build, CI runner, bench testing. Always powered, on the LAN |
-| Car Orin | Deployment target only |
+| Development Orin (`mikkeli-orin-nano-2`) | Build, CI runner, bench testing. Always powered, on the LAN |
+| Car Orin (`mikkeli-orin-nano`) | Deployment target only |
+
+The SIM7600 LTE/GNSS hat lives in the car unit only — its custom enclosure doesn't
+move between units. Anything touching the modem or gpsd is tested on the car unit;
+on the development unit, `gnss` runs against its own mock input (decision 19).
 
 ⚠ **The guarantee is version parity, not architecture.** An aarch64 binary built
 on a newer userland still fails to load on an older one. A JetPack or Ubuntu

docs/ROADMAP.md

@@ -1,7 +1,7 @@
 ---
 type: plan
 status: active
-updated: 2026-09-04
+updated: 2026-10-08
 ---
 # Roadmap
 
@@ -12,11 +12,19 @@ something demonstrable in the car.
 
 Getting the Jetson to see the hardware at all.
 
-- [x] PCAN-USB working as SocketCAN `can1` (out-of-tree `pcan.ko`, netdev build)
+- [x] PCAN-USB working as SocketCAN (out-of-tree `pcan.ko`, netdev build)
+- [x] Stable CAN names by udev: `can_pcan`, `can_onboard` — `canN` order raced at boot
 - [x] SIM7600G-H-M.2 specified and documented
-- [ ] SIM7600 brought up: LTE data path and GNSS via gpsd
-- [ ] Kernel-update procedure for the out-of-tree PCAN module — it does not
-      survive kernel upgrades and will break silently
+- [x] SIM7600 LTE data path: QMI (self-built `qmi_wwan`), povo, metered, ranked
+      below Ethernet/WiFi; failover tested, Tailscale stays reachable over LTE
+- [ ] SIM7600 GNSS via gpsd — pipeline up (`/dev/sim7600-gps`), **no fix yet**;
+      needs an open-sky test
+- [x] Kernel-update procedure for the out-of-tree modules (`pcan`, `qmi_wwan`) —
+      documented, sources kept in `~/infra`; still manual, and breaks silently
+      if forgotten
+- [x] Network time pinned to NICT; timezone `Asia/Tokyo`
+- [ ] Optional: RTC backup battery (CR2032) — without it the clock boots stale
+      until NTP or GPS corrects it
 - [ ] Power and mounting in the car: clean shutdown on ignition off
 
 Tracked in [orin-nano-env-setup](gitea:yukart/orin-nano-env-setup).
@@ -79,7 +87,7 @@ and `tool-mapmint` (artifact builds).
 - [ ] Pull a Japan basemap extract from the Protomaps daily build with
       `go-pmtiles`; static-serve it, with `localIdeographFontFamily` set for CJK
 - [ ] MapLibre page rendering the basemap from a replayed GNSS trace
-- [ ] Moving map live in the car — **blocked on gpsd in Phase 0**
+- [ ] Moving map live in the car — **blocked on a GNSS fix in Phase 0**
 - [ ] Meili map matching over recorded sessions, as Phase 2 ground truth
 - [ ] Routing and turn-by-turn guidance onto `yukart/nav/guidance`