Controller Area Network

Computer Networks

Layers, protocols, and interfaces

CAN Basic Concepts

Prioritization of messages Configuration flexibility Multicast reception with time synchronization Multimaster Error detection and signaling Automatic retransmission of corrupted message Distinction between temporary errors and permanent failures of

nodes and autonomous switching off of detect node

Layer structure of a CAN node

CAN Messages

Frame Type:

Data frame

Format of standard data frame

Format of extended data frame

There are three CAN Specification versions:

• 2.0A – considers 29-bit identifier as error

• 2.0B Passive – ignores 29-bit identifier messages

• 2.0B Active – handles both 11-bit and 29-bit identifiers

CRC field

ACK field

- Remote frame

Format of standard remote frame

Format of extend data frame

- Error frame

Error detection & correction

1. Bit Monitoring. 2. Bit Stuffing. 3. Frame Check. 4. Acknowledgement Check. 5. Cyclic Redundancy Check

- Interframe space

- Overload frame

Bit timing

34.5 CAN MODULE OPERATING MODES

Configuration mode Normal Operation mode Listen-Only mode Listen All Messages mode Loopback mode Disable mode