mikkeli
cce9711119
obd-poller drops its CAN socket: the Z27AG answers OBD-II only on ISO 9141-2. It holds a raw RFCOMM link to the ELM (no pairing, no root), fixes the protocol (ATSP3) so nothing probes CAN, publishes the obd_* signals, and releases the adapter after a minute of ECU silence so it can sleep. gnss: gpsd's fix as yukart/gnss/<signal>. orin-status: elm_connected from BlueZ. One native deploy script (deploy-native.sh BIN) behind the per-service ones; /etc/default/yukart-elm holds the adapter's address. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01DDwfd6Ki8UfG4hK6W5YpJz
39 lines
1.8 KiB
Markdown
39 lines
1.8 KiB
Markdown
---
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type: guidelines
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---
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# Core services guidelines
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## 1. One writer: `obd-poller`, and never on CAN
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- `obd-poller` is the only thing that sends anything to the car (project-yukart
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decisions 3 and 30): OBD-II requests, one at a time, on the K-line through the
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Bluetooth ELM327, with the ELM's protocol fixed so it never probes CAN.
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- Nothing in svc-core transmits on CAN. The recorder and the decoder only read;
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anything else that writes to `can_pcan` is a bug.
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- `can_pcan` still acknowledges frames like any scan tool (listen-only off since
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2026-10-12, left so as harmless). Going back is one line in orin-nano-env-setup's
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`/etc/default/can-can_pcan`.
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## 2. Capture never waits
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- A frame missed is gone. Producers hand frames to the writer without blocking;
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what doesn't fit is **counted**, recorded as an event, and never silently lost.
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- Capture reads SocketCAN and gpsd directly. It does not depend on the broker, a
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display, or any other service being up.
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## 3. Every failure leaves complete files
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- Append, flush and `fdatasync` about once a second. Power loss costs at most the
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last second.
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- Replace files by write-temp, fsync, rename. Never rewrite in place.
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- Anything found half-done at startup is repaired or marked, not deleted.
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## 4. Raw stays raw
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- Recordings are `candump -L` text plus the gpsd JSON as received, so `can-utils`,
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`canplayer` and anything already written against the first captures keep working.
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- Decoding happens downstream of the recording, never instead of it.
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## 5. Time is evidence, not truth
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- The car unit's clock can boot stale and be stepped mid-drive. Record what is
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needed to correct it later (sync state, monotonic time, observed steps, GNSS
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time beside local receive time) rather than trusting it.
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## 6. To be added
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