CAN docs: OBD-II is on the K-line via the ELM; nothing transmits on CAN
/ crosscheck (push) Successful in 1s

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01DDwfd6Ki8UfG4hK6W5YpJz
This commit is contained in:
2026-10-13 22:57:32 +09:00
parent 1551e5648a
commit 00082ac491
2 changed files with 5 additions and 4 deletions
+1 -1
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@@ -31,7 +31,7 @@ All ports are taken.
| **USB ID** | `0c72:000c` | | **USB ID** | `0c72:000c` |
| **Purpose** | USB-to-CAN adapter for reading car CAN bus traffic | | **Purpose** | USB-to-CAN adapter for reading car CAN bus traffic |
| **Interface** | SocketCAN netdev | | **Interface** | SocketCAN netdev |
| **Bitrate** | 500 kbps, measured on the Z27AG OBD port (not listen-only since 2026-10-12: obd-poller sends OBD-II requests; see [CAN bitrate plan](impl/plans/CAN-BITRATE.md)) | | **Bitrate** | 500 kbps, measured on the Z27AG OBD port (not listen-only since 2026-10-12, though nothing transmits on CAN now: OBD-II goes over the K-line via the ELM327; see [CAN bitrate plan](impl/plans/CAN-BITRATE.md)) |
| **Driver** | PEAK proprietary driver 9.2.0 (netdev build) — out-of-tree module, must be rebuilt after kernel updates | | **Driver** | PEAK proprietary driver 9.2.0 (netdev build) — out-of-tree module, must be rebuilt after kernel updates |
### Notes ### Notes
+4 -3
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@@ -28,8 +28,9 @@ Persisted (boot and hot-plug):
(svc-core), the single writer: the adapter now acknowledges frames like any scan tool. To go back, set (svc-core), the single writer: the adapter now acknowledges frames like any scan tool. To go back, set
`CAN_OPTS="listen-only on restart-ms 100"` there and replug the PEAK (or restart `can-up@can_pcan`). `CAN_OPTS="listen-only on restart-ms 100"` there and replug the PEAK (or restart `can-up@can_pcan`).
obd-poller is **disabled since 2026-10-13**: the Z27AG's ECU never answered OBD-II on CAN (most likely K-line, pin 7, The Z27AG's ECU never answered OBD-II on CAN: it speaks ISO 9141-2 on the K-line (pin 7), confirmed through an ELM327
not wired). The adapter was left acknowledging anyway, as harmless at the measured bitrate. on 2026-10-13. obd-poller now polls through that ELM over Bluetooth, so **nothing transmits on CAN**. The adapter was left
acknowledging anyway, as harmless at the measured bitrate.
## Goal ## Goal
@@ -57,7 +58,7 @@ Not set yet on purpose: no persistent bitrate until it's measured.
**If every rate shows 0 frames:** the OBD port is probably behind a gateway that stays silent unless queried. Then the bitrate has to be found **If every rate shows 0 frames:** the OBD port is probably behind a gateway that stays silent unless queried. Then the bitrate has to be found
by sending one standard OBD-II request (ISO 15765-4: try 500k, then 250k), e.g. mode 01 PID 00 to `0x7DF`. That's transmitting, so it by sending one standard OBD-II request (ISO 15765-4: try 500k, then 250k), e.g. mode 01 PID 00 to `0x7DF`. That's transmitting, so it
belongs to the single CAN writer (`obd-poller`, project-yukart decision 3). Do it deliberately, not as part of a sniff. belongs to the single writer (`obd-poller`, project-yukart decision 3). Do it deliberately, not as part of a sniff.
## After the rate is known ## After the rate is known