The app now speaks the station-link protocol of the new obu-firmware.
Esp32Link picks the transport from Settings (UsbSerialTransport or the new
BleLinkTransport), tells the previous firmware from the new one by its
heartbeat, and runs the session: STATION_CONFIGURE with the current pseudonym
MAC (which also starts the board's radio), CREDENTIALS_PROVISION of the
bundled demo chain when the board has no ticket, then per message a
POTI_UPDATE and a BTP_DATA_REQUEST. Received messages still arrive as
V2X_RX frames, so the receive side is unchanged. A board on the previous
firmware keeps working for CAM over USB.
Settings > Connection > ESP32-C5: link USB-C or Bluetooth, transmit CAM or
VAM, "Sign outgoing messages" (on by default). The connection card, top bar
and dashboard show the link in use, the pairing passkey and signing counters.
- VAM: VamUperCodec (TS 103 300-3 V2.3.1, bytes checked against asn1tools)
and VamGenerationRules (clause 6.4, Tables 16/17).
- BLE: the firmware's GATT layout (service 0000C175-...), MTU 517, pairing
and encryption settled before any other operation (short timeouts during
pairing made it loop), backoff between attempts, reasons on the card.
- Clock: a PoTi goes to the board once per new fix and never moves the
board's clock backwards except for a real correction (>= 60 s); stale and
wobbling fix times made the board answer time_regression and restart its
stack every few seconds. GnssTimeSource keeps the last measured phone-clock
error while GNSS time drops out indoors: the bench phone is 14 minutes fast,
and falling back to it made every transmitted timestamp jump by that much.
- assets/demo-chain.vcr: throwaway, not EU-registered demo chain generated
2026-09-23 (AT B80B49387A4C12EB, psid 36 and 638). Its private key ships
with the app on purpose; receivers verifying against the EU trust list
drop what it signs.
- Bluetooth permissions requested at start-up on Android 12+.
StationLinkTest pins the codec to bytes from the colleague's Python
implementation (microbu_link/messages.py). 103 unit tests pass.
Ashin Walpola
a08494b56a