Microcontroller User's Manual

MOTOROLA Chapter 25. FlexCAN 25-1
Chapter 25
FlexCAN
The FlexCAN module is a communication controller implementing the controller area
network (CAN) protocol, an asynchronous communications protocol used in automotive
and industrial control systems. It is a high speed (1 Mbit/sec), short distance, priority based
protocol which can communicate using a variety of mediums (for example, fiber optic cable
or an unshielded twisted pair of wires). The FlexCAN supports both the standard and
extended identifier (ID) message formats specified in the CAN protocol specification,
revision 2.0, part B.
The CAN protocol was primarily, but not only, designed to be used as a vehicle serial data
bus, meeting the specific requirements of this field: real-time processing, reliable operation
in the EMI environment of a vehicle, cost-effectiveness and required bandwidth. A general
working knowledge of the CAN protocol revision 2.0 is assumed in this document. For
details, refer to the CAN protocol revision 2.0 specification.
25.1 Features
• Based on and includes all existing Motorola TouCAN module features
• Motorola IP interface architecture
• Full implementation of the CAN protocol specification version 2.0
— Standard data and remote frames (up to 109 bits long)
— Extended data and remote frames (up to 127 bits long)
— 0–8 bytes data length
— Programmable bit rate up to 1Mbit/sec
• Up to 16 flexible message buffers of 0–8 bytes data length, each configurable as Rx
or Tx, all supporting standard and extended messages
• Listen-only mode capability
• Content-related addressing
• No read/write semaphores
• Three programmable mask registers: global (for MBs 0-13), special for MB14, and
special for MB15
• Programmable transmit-first scheme: lowest ID or lowest buffer number