Introduction - Freescale Semiconductor MCF52277 Reference Manual

Chapter 23
FlexCAN
23.1

Introduction

The FlexCAN 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 Mbps), short distance, priority-based protocol that can communicate using a variety of mediums
(such as fiber optic cable or an unshielded twisted pair of wires). The FlexCAN supports 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.
23.1.1 Block Diagram
A block diagram describing the various submodules of the FlexCAN module is shown in
Each submodule is described in detail in subsequent sections.
FlexCAN
RXIMR15
RXIMR14
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RXIMR3
RXIMR2
RXIMR1
RXIMR0
Freescale Semiconductor
MB15
MB14
• •
• •
• •
• •
• •
• •
• •
• •
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MB3
MB2
MB1
MB0
Internal Bus Interface
Figure 23-1. FlexCAN Block Diagram
MCF52277 Reference Manual, Rev. 1
Message
Buffer
Management
CAN
Protocol
Max MB #
Interface
[0:15]
Bus Interface Unit
Clocks, Address and Data Buses,
Interrupt and Test Signals
Figure 23-1.
CANTX
CANRX
23-1