Freescale Semiconductor MCF5480 - Manual (Page 571)

MCF548x Reference Manual, Rev. 3
Freescale Semiconductor 21-1
Chapter 21
FlexCAN
21.1 Introduction
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 Mbps), short distance, priority-based protocol that 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.
21.1.1 Block Diagram
A block diagram describing the various submodules of the FlexCAN module is shown in Figure 21-1 .
Each submodule is described in detail in subsequent sections. The message buffer architecture is shown in
Figure 21-2 .
Figure 21-1. FlexCAN Block Diagram and Pinout
MB15
MB14
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MB3
MB2
MB1
MB0
Clocks, Address and Data Buses,
CAN
Protocol
Interface
Message
Buffer
Management
CANTx
CANRx
Bus Interface Unit
Max MB #
[0:15]
IP-Bus Interface
Interrupt and Test Signals
FlexCAN
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