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CAN bus

Controller Area Network — a robust, differential, multi-master bus designed for noisy automotive/industrial environments. Devices broadcast messages (by ID, not address) and hardware arbitration decides priority.

Pros & cons​

ProsCons
Very noise-immune (differential, twisted pair)Needs a controller and a transceiver
Multi-master, no single point of controlModest raw rate (1 Mbps classic; CAN-FD faster)
Prioritised arbitration (no collisions lost)Requires correct termination
Strong error detection + auto-retransmitMore software setup than UART/I²C
Good over tens of metres

Use cases​

  • Automotive (its origin), robotics, industrial automation, motor controllers, distributed sensor/actuator networks where reliability matters.

Hardware requirements​

  • A CAN controller (built into many MCUs) + a CAN transceiver (e.g. TJA1050, MCP2551).
  • Twisted pair CANH/CANL with 120 Ω termination at both ends of the bus.
  • Common ground reference; galvanic isolation for long runs or different ground potentials.

Software requirements​

  • Configure bit timing (sample point) — must match across all nodes.
  • Set up message IDs, acceptance filters/masks, and TX/RX mailboxes.
  • Handle errors and bus-off recovery.
  • Optionally a higher-layer protocol: CANopen, J1939.
Top CAN failures

Termination wrong/missing (one 120 Ω at each end — not more), bit-timing mismatch between nodes, or no transceiver. A ground offset between far nodes also corrupts data — isolate.

See also​