| name | canbus-integration |
| description | Use when integrating, porting, configuring, or debugging CAN bus libraries, CANBus-Triple, MCP2515, CAN frames, bit timing, filters, or embedded automotive communication |
CANBus Integration
Overview
Use this skill for embedded CAN bus libraries and CANBus-Triple style projects. CAN failures are often physical-layer, bit-timing, termination, transceiver, or filter problems before they are application protocol problems.
When To Use
Use this skill when:
- The user mentions CAN, CANBus-Triple, MCP2515, SocketCAN, CANopen, J1939, UDS, OBD-II, ISO-TP, or automotive messages.
- Frames are missing, bus-off occurs, IDs are wrong, filters reject messages, or bit timing is unreliable.
- The task involves adapting a CAN example project or Arduino-style CAN platform to another board.
Do not use this skill when the target is only a generic UART/SPI issue with no CAN layer.
First Questions
Ask for:
- CAN controller/transceiver and board, such as internal CAN, FDCAN, MCP2515, or CANBus-Triple.
- Bus speed, oscillator frequency, sample point, and whether CAN FD is involved.
- Wiring, termination, transceiver voltage, and whether another known-good node is present.
- Frame IDs, standard/extended format, filters, masks, and expected traffic.
- Library/project source and current error counters, bus state, or capture.
Integration Checklist
-
Verify physical layer.
Confirm CANH/CANL wiring, 120-ohm termination, common ground, transceiver enable/standby, and voltage compatibility.
-
Confirm bit timing.
Controller clock, prescaler, segments, sample point, and bus speed must match the network.
-
Start with listen or loopback.
Use internal loopback or listen-only mode before transmitting onto a live bus.
-
Configure filters deliberately.
Disable filters temporarily or accept all frames to prove RX path before narrowing IDs.
-
Separate transport and protocol.
First prove raw CAN frames, then add ISO-TP, UDS, OBD-II, J1939, or application decoding.
-
Protect live systems.
Do not transmit on vehicle or production buses without explicit approval and a safe test plan.
Common Failures
- Missing termination or wrong transceiver standby pin.
- MCP2515 oscillator frequency differs from library assumption.
- Standard versus extended ID mismatch.
- Filters silently drop expected frames.
- Bus-off caused by transmitting at wrong bit rate.
- SPI-to-CAN driver works in loopback but fails due to transceiver wiring.
Verification
Before claiming CAN works:
- State controller, transceiver, bus speed, clock, ID format, and filter mode.
- Confirm physical termination and transceiver enable state.
- Confirm loopback or known-good RX before live TX.
- Report error counters, bus state, and captured frame evidence.
- State whether transmission on a live bus was skipped or explicitly approved.
Example
User:
CANBus-Triple 例程烧进去后收不到车上的 CAN 帧。
Agent:
- Asks for bus speed, MCP2515 oscillator, termination, transceiver state, and expected IDs.
- Tests listen-only or accept-all filters.
- Confirms raw frames before decoding OBD-II or UDS traffic.
